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Question 861Question →

A 65-year-old man is brought to the emergency department via ambulance due to sudden, severe, and tearing chest pain that radiates directly to his back between the shoulder blades. The pain began 45 minutes ago while he was resting. His medical history is significant for poorly controlled hypertension, type 2 diabetes mellitus, and stage 4 chronic kidney disease. Upon arrival, he appears in acute distress. His temperature is 37.1°C (98.8°F), blood pressure is 195/110 mm Hg in the right arm and 175/95 mm Hg in the left arm, pulse is 112/min, and respirations are 22/min. Physical examination reveals a new early diastolic decrescendo murmur heard best at the right upper sternal border. The lungs are clear to auscultation bilaterally. Neurologic examination shows no focal deficits. Laboratory studies demonstrate a serum creatinine level of 3.6 mg/dL (baseline 2.9 mg/dL) and a blood urea nitrogen of 48 mg/dL. An electrocardiogram shows left ventricular hypertrophy and sinus tachycardia, but no acute ischemic changes. A portable chest radiograph reveals a widened mediastinum. Which of the following is the most appropriate next step in imaging for this patient?

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Answer: Transesophageal echocardiography

Answer

Transesophageal echocardiography
The patient's classic presentation (tearing chest pain, unequal blood pressures, new diastolic murmur, widened mediastinum) strongly suggests an acute aortic dissection. To definitively diagnose a dissection, imaging of the entire aorta is required. The most accurate imaging studies are computed tomography angiography (CTA), transesophageal echocardiography (TEE), and magnetic resonance angiography (MRA). Because this patient has significant renal failure (creatinine 3.6 mg/dL), the iodinated contrast required for a CTA is contraindicated. MRA is inappropriate in an acute emergency because it is time-consuming and its gadolinium contrast poses a risk for nephrogenic systemic fibrosis in severe renal disease. Therefore, TEE is the most appropriate next step because it has excellent sensitivity and specificity for aortic dissection, uses no contrast, and can be rapidly performed at the bedside.

Step-by-Step Solution

1
Analyze the patient's presentation.
The patient has tearing chest pain radiating to the back, asymmetric blood pressures, a new murmur of aortic regurgitation, and a widened mediastinum.
These findings are highly suspicious for an acute aortic dissection.
2
Evaluate the patient's comorbidities and laboratory results.
The patient has underlying stage 4 chronic kidney disease with an acute elevation in serum creatinine (3.6 mg/dL).
Severe renal dysfunction dictates which imaging modalities are safe, as certain contrast agents are contraindicated.
3
Select the optimal imaging modality.
Transesophageal echocardiography is chosen over computed tomography angiography.
Transesophageal echocardiography has high sensitivity and specificity for aortic dissection, avoids nephrotoxic iodinated contrast, and can be rapidly performed in acute settings.

Key Concept

In patients with suspected acute aortic dissection who have severe renal dysfunction or hemodynamic instability, transesophageal echocardiography is the preferred diagnostic imaging modality over computed tomography angiography.
Estimated Time:1m 30s
Question 862Question →

An adult patient is referred to an endocrinology clinic due to progressive changes in facial features, widening of the hands, and hyperhidrosis developing over the past three years. The primary care provider obtained initial screening laboratory studies, which revealed a serum insulin-like growth factor-1 (IGF-1) concentration substantially above the upper limit of normal for the patient's age and sex. Renal and hepatic function panels are unremarkable. Which of the following is the most appropriate next step in the diagnostic evaluation of this patient?

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Answer: Measurement of serum growth hormone following an oral glucose load

Answer

Measurement of serum growth hormone following an oral glucose load
The correct next step is to perform an oral glucose tolerance test (OGTT) with concurrent measurement of serum growth hormone (GH) levels. The diagnostic workup for suspected acromegaly follows a strict, step-wise sequence to ensure diagnostic accuracy. Because GH is secreted in a highly pulsatile manner, a single random GH measurement is clinically unhelpful. Instead, serum insulin-like growth factor-1 (IGF-1) is used as the initial screening test because it provides an integrated measure of GH secretion over time and has a long half-life. Once an elevated IGF-1 level suggests the diagnosis, it must be biochemically confirmed by demonstrating the loss of normal physiologic feedback. Under normal physiologic conditions, a glucose load robustly suppresses GH secretion. Therefore, the failure of GH to suppress to less than 1 ng/mL following a standard 75g oral glucose load confirms the diagnosis of autonomous GH hypersecretion. Only after this definitive biochemical confirmation is achieved should structural imaging (such as an MRI of the sella turcica) be ordered to localize the source, which is typically a pituitary adenoma.

Step-by-Step Solution

1
Identify the suspected clinical diagnosis based on the patient's presentation.
The patient has classic somatic features of acromegaly, supported by a significantly elevated screening IGF-1 level.
Recognizing the condition and the current stage of the diagnostic algorithm dictates the subsequent workup.
2
Determine the guideline-recommended sequence for confirming this specific condition.
An elevated screening IGF-1 level requires definitive biochemical confirmation of autonomous growth hormone (GH) secretion prior to ordering structural imaging.
Because pituitary incidentalomas are common in the general population, biochemical proof of disease must precede anatomical localization to prevent false-positive diagnostic attributions.
3
Select the appropriate biochemical confirmatory test.
The oral glucose tolerance test (OGTT) with GH measurement is selected.
In healthy individuals, a glucose load suppresses GH secretion. Failure of GH to suppress to normal limits confirms autonomous hypersecretion.

Key Concept

The diagnostic sequencing of acromegaly requires initial screening with serum IGF-1, followed by biochemical confirmation using an oral glucose tolerance test (OGTT) to demonstrate failure of growth hormone suppression, prior to obtaining an MRI of the pituitary gland.
Question 863Question →

A geriatric care physician evaluates an 82-year-old male resident who abruptly developed generalized, severe abdominal pain and a rigid, board-like abdomen. Vital signs show a heart rate of 112/min, a respiratory rate of 22/min, and a temperature of 38.1°C (100.6°F). An upright chest radiograph is immediately obtained and demonstrates a distinct, thin crescent of radiolucency located directly between the right hemidiaphragm and the superior margin of the liver. Based on this specific radiographic finding, which of the following is the most likely diagnosis?

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Answer: Gastrointestinal viscus perforation

Answer

Gastrointestinal viscus perforation
The clinical scenario describes a patient with peritonitis (rigid, board-like abdomen) whose upright chest radiograph shows a radiolucent crescent beneath the right hemidiaphragm. This finding represents free air in the peritoneal cavity (pneumoperitoneum). Gas rises to the highest point in the abdomen when the patient is upright, interposing itself between the liver and the diaphragm. In a patient with an acute abdomen, this strongly points to a perforated hollow viscus, such as a perforated peptic ulcer or diverticulum.

Step-by-Step Solution

1
Analyze the patient's clinical presentation.
The patient has an acute, rigid abdomen with tachycardia and fever, suggesting a severe intra-abdominal catastrophe like peritonitis.
Identifying the acuity and physical exam findings guides the interpretation of the subsequent imaging.
2
Interpret the radiographic findings.
The upright chest radiograph shows a 'crescent of radiolucency' between the right hemidiaphragm and the liver.
This specific description is the classic radiographic appearance of pneumoperitoneum (free intraperitoneal air).
3
Correlate the imaging finding with the differential diagnosis.
Pneumoperitoneum in the setting of an acute, rigid abdomen almost universally points to a perforated hollow viscus.
Air normally contained within the gastrointestinal tract escapes into the peritoneal cavity when a viscus (like an ulcerated stomach or duodenum) perforates.

Key Concept

The presence of a radiolucent crescent under the right hemidiaphragm on an upright chest radiograph signifies pneumoperitoneum, which, in the context of an acute abdomen, most commonly indicates a perforated hollow viscus.
Estimated Time:45s
Question 864Question →

An 82-year-old woman is rushed to the emergency department by her family. She was eating breakfast 30 minutes ago when she suddenly developed left-sided facial droop, slurred speech, and left arm weakness. Her vital signs are stable, but her electrocardiogram shows atrial fibrillation. The stroke team is activated to evaluate her for potential thrombolysis and mechanical thrombectomy. Arrange the following imaging studies in the standard sequential order for the diagnostic workup of this acute presentation, starting with the immediate initial test.

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Answer

The correct sequence is to first perform a non-contrast CT of the head, followed by a CTA of the head and neck, and finally an MRI of the brain at a later subacute stage.
The standard protocol for acute stroke imaging prioritizes speed and the rapid exclusion of contraindications for reperfusion therapy. A non-contrast CT is performed first to immediately rule out hemorrhage. Once hemorrhage is excluded, a CTA is indicated to evaluate for large vessel occlusions that would benefit from mechanical thrombectomy. Finally, an MRI is typically performed 24 to 48 hours later to clearly define the infarct size, location, and potential etiology, as it is the most sensitive modality but too time-consuming for the hyperacute triage phase.

Step-by-Step Solution

1
Identify the critical immediate decision point for acute stroke management.
The most urgent need is to differentiate ischemic stroke from hemorrhagic stroke to determine eligibility for thrombolytic therapy.
Administration of thrombolytics in a patient with a hemorrhagic stroke is strictly contraindicated and potentially fatal.
2
Select the most rapid and appropriate initial imaging modality.
Non-contrast CT of the head.
It is widely available, very fast, and highly sensitive for detecting acute intracranial hemorrhage, making it the standard of care for initial stroke imaging.
3
Determine the next immediate imaging step to guide further acute interventional management.
Computed tomography angiography (CTA) of the head and neck.
Once hemorrhage is excluded, identifying a proximal large vessel occlusion is necessary to determine if the patient is a candidate for endovascular mechanical thrombectomy.
4
Identify the role of more advanced, sensitive imaging in the stroke pathway.
Magnetic resonance imaging (MRI) of the brain.
While highly sensitive for acute ischemia, MRI takes significantly longer; it is best utilized for subacute evaluation to define the exact infarct core and investigate the underlying etiology once the hyperacute phase has passed.

Key Concept

In acute stroke evaluation, imaging must be sequenced to prioritize rapid exclusion of hemorrhage (non-contrast CT) and identification of large vessel occlusion (CTA), while reserving more time-consuming definitive imaging (MRI) for later characterization.
Question 865Question →

A 72-year-old woman is brought to the emergency department from a long-term care facility due to progressively worsening lethargy over the past 24 hours. The transport personnel report that her indwelling urinary catheter is draining dark, foul-smelling, and turbid urine. Her temperature is 39.2°C (102.6°F), blood pressure is 78/40 mm Hg, pulse is 128/min, and respirations are 24/min. Pulse oximetry shows 95% on room air. On physical examination, the patient is obtunded but groans and withdraws all four extremities in response to a sternal rub. Her mucous membranes are dry, and capillary refill time is delayed (4 seconds). Which of the following are the most critical immediate steps in the stabilization and management of this patient? (Select exactly two options)

Select all that apply

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Answer: Administration of a rapid intravenous crystalloid fluid bolus; Empiric administration of broad-spectrum intravenous antibiotics

Answer

The most critical immediate steps are the administration of a rapid intravenous crystalloid fluid bolus and the empiric administration of broad-spectrum intravenous antibiotics.
The patient is presenting with classic signs of septic shock, including severe hypotension, tachycardia, fever, lethargy, and a clear suspected infectious source in the urinary tract. According to current evidence-based sepsis guidelines, the most critical initial stabilization steps involve simultaneously addressing perfusion and the underlying infection. This requires rapid fluid resuscitation (typically starting with 30 mL/kg of IV crystalloids) to restore intravascular volume and tissue perfusion, combined with the immediate administration of broad-spectrum intravenous antibiotics. These interventions must be initiated simultaneously within the first hour of recognition to significantly reduce patient mortality.

Step-by-Step Solution

1
Assess the patient's airway, breathing, and circulation (ABCs).
Airway is patent and breathing is adequate (SpO2 95%), but circulation is severely compromised (hypotension, tachycardia, delayed capillary refill).
Airway, breathing, and circulation are the first priorities in the primary survey of any unstable patient.
2
Identify the likely etiology of the shock state.
The clinical presentation (fever, purulent urine, severe hypotension) strongly points to septic shock secondary to a urinary tract infection.
Identifying the primary shock phenotype guides specific life-saving resuscitation targets.
3
Initiate the core components of early goal-directed therapy for sepsis simultaneously.
Administer rapid intravenous crystalloids and broad-spectrum antibiotics.
Concurrent volume resuscitation and infection source control are the foundational, proven life-saving steps for reversing septic shock and improving mortality.

Key Concept

Initial stabilization of septic shock using simultaneous fluid resuscitation and broad-spectrum antibiotic administration.
Question 866Question →

Match the following classic thoracic imaging findings to their most likely corresponding clinical diagnosis.

Click a left item, then click its matching right item

Items

Kerley B lines, cardiomegaly, and cephalization of pulmonary vessels on chest radiograph
Bilateral symmetrical hilar and mediastinal lymphadenopathy on chest computed tomography
Peripheral, bibasilar reticular opacities with honeycomb cystic changes on high-resolution computed tomography
Deep sulcus sign and visceral pleural line lacking distal lung markings on chest radiograph

Matches

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Answer

Kerley B lines and cephalization pair with acute decompensated heart failure; bilateral hilar lymphadenopathy pairs with sarcoidosis; honeycombing pairs with idiopathic pulmonary fibrosis; and a pleural line lacking markings pairs with pneumothorax.
Each provided imaging finding is a highly specific, pathognomonic sign for its respective disease process. Accurate pattern recognition of these classic thoracic presentations is fundamental for establishing a correct diagnosis and initiating appropriate management.

Step-by-Step Solution

1
Analyze the imaging finding of Kerley B lines, cardiomegaly, and cephalization.
Identified as signs of elevated pulmonary venous pressure and fluid overload.
These findings directly point to volume overload, matching with acute decompensated heart failure.
2
Evaluate the finding of bilateral hilar lymphadenopathy.
Recognized as a classic granulomatous disease presentation on chest imaging.
This specific symmetrical distribution strongly matches sarcoidosis in the absence of an acute infectious context.
3
Assess the bibasilar reticular opacities and honeycombing.
Identified as the usual interstitial pneumonia (UIP) pattern.
This specific high-resolution CT pattern is a diagnostic hallmark of idiopathic pulmonary fibrosis.
4
Review the deep sulcus sign and visceral pleural line.
Recognized as air accumulating in the pleural space.
Absent distal lung markings and an abnormally deep costophrenic angle indicate a pneumothorax.

Key Concept

Interpreting classic thoracic imaging patterns to establish pulmonary and cardiac diagnoses
Question 867Question →

A 65-year-old man who is a current smoker presents to the clinic for a routine wellness examination. A screening chest radiograph reveals a 1.51.5-cm solitary pulmonary nodule in the right upper lobe. He recently relocated and has no previous medical records at this facility. Arrange the following diagnostic steps in the most appropriate sequential order for the evaluation of this finding, proceeding from the initial best next step to the final definitive diagnostic procedure.

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Answer

The correct sequence of diagnostic testing is: 1) Obtain and review prior chest imaging, 2) Computed tomography (CT) of the chest without contrast, 3) Positron emission tomography (PET) scan, and 4) Image-guided transthoracic needle biopsy.
The evaluation of a solitary pulmonary nodule follows a strict, tiered approach to minimize unnecessary invasive testing while accurately diagnosing potential malignancy. The absolute first step is always obtaining old imaging to assess for stability; stability over 24 months generally indicates a benign etiology. If the nodule is new or prior imaging is unavailable, a dedicated chest CT is required for detailed anatomical characterization. For nodules larger than 8 mm with intermediate clinical suspicion (as in an older smoker), a PET scan is used to risk-stratify the metabolic activity of the lesion. Finally, if the nodule is highly suspicious or PET-avid, an invasive tissue biopsy is performed to confirm the histopathological diagnosis.

Step-by-Step Solution

1
Assess for chronicity with existing data
Obtain and review prior chest imaging.
This is the most cost-effective, non-invasive first step to determine if the nodule is stable, which strongly points toward a benign etiology.
2
Characterize the nodule anatomically
Order a computed tomography (CT) scan of the chest without contrast.
A CT scan provides detailed morphological features (calcification pattern, margins, exact size) necessary to calculate the pre-test probability of malignancy.
3
Evaluate metabolic activity
Perform a positron emission tomography (PET) scan.
For intermediate-risk nodules larger than 8 mm, functional imaging helps differentiate between benign and malignant lesions before committing to an invasive procedure.
4
Obtain definitive tissue diagnosis
Perform an image-guided transthoracic needle biopsy.
This is the definitive, though most invasive, final step to confirm the histopathology of a highly suspicious nodule, guiding subsequent surgical or oncologic management.

Key Concept

Diagnostic Workup and Test Sequencing for Solitary Pulmonary Nodule
Question 868Question →

A 54-year-old woman with a history of hypothyroidism secondary to Hashimoto thyroiditis undergoes a right thyroid lobectomy for a 3.5-cm solid nodule. Preoperative fine-needle aspiration was reported as Bethesda Category IV (suspicious for a follicular neoplasm). The surgical pathology report of the resected lobe describes a well-circumscribed, entirely encapsulated tumor composed exclusively of closely packed follicles. Microscopic examination of the follicular epithelial cells reveals nuclear enlargement, overlapping nuclei, prominent longitudinal nuclear grooves, and central chromatin clearing. Two microscopic psammoma bodies are identified within the lesion. Extensive sampling shows no evidence of capsular penetration or vascular invasion by the tumor cells.

Based on these histopathologic findings, which of the following is the most accurate diagnostic interpretation?

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Answer: Papillary thyroid carcinoma, as the characteristic nuclear features are diagnostic even in the absence of invasion

Answer

Papillary thyroid carcinoma, as the characteristic nuclear features are diagnostic even in the absence of invasion
The pathology report describes classic nuclear features of papillary thyroid carcinoma (PTC): enlarged, overlapping nuclei with longitudinal grooves and chromatin clearing ('Orphan Annie eyes'). In thyroid pathology, the presence of these nuclear features is the gold standard for diagnosing PTC, even when the tumor has an exclusively follicular growth pattern (follicular variant of PTC) and lacks any signs of capsular or vascular invasion. The finding of psammoma bodies further cements the diagnosis of PTC and explicitly rules out more indolent classifications such as NIFTP (Non-invasive follicular thyroid neoplasm with papillary-like nuclear features), which strictly requires the absence of psammoma bodies.

Step-by-Step Solution

1
Analyze the architectural and cytologic features described in the pathology report.
The tumor is encapsulated with a follicular architecture, but displays nuclear enlargement, overlapping, grooves, and chromatin clearing (Orphan Annie eyes), along with psammoma bodies.
Identifying these specific cytologic findings is the critical first step in classifying thyroid neoplasms.
2
Determine if the nuclear features override the tumor's architecture and lack of invasion.
The presence of classical PTC nuclear features dictates a diagnosis in the papillary carcinoma family, regardless of the strictly follicular architecture or the absence of capsular/vascular invasion.
Diagnostic criteria for PTC are driven by cytology, whereas follicular carcinoma/adenoma differentiation is driven by invasion.
3
Evaluate the possibility of a non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP).
Although the tumor is non-invasive and encapsulated, the presence of psammoma bodies is an absolute exclusion criterion for NIFTP.
NIFTP has strict inclusion and exclusion criteria to prevent over-treating indolent lesions, and psammoma bodies confirm classic PTC biology.

Key Concept

The diagnosis of papillary thyroid carcinoma (PTC) relies on characteristic nuclear features (grooves, pseudoinclusions, chromatin clearing) and is independent of capsular or vascular invasion, which are the criteria used to differentiate follicular adenoma from follicular carcinoma.
Question 869Question →

A 29-year-old woman, estimated to be at 34 weeks gestation, is brought to the emergency department following a high-speed motor vehicle collision. Paramedics report she was an unrestrained driver and was found unresponsive at the scene. Upon arrival, her Glasgow Coma Scale score is 6. Vital signs include a heart rate of 148/min, blood pressure of 65/35 mm Hg, respiratory rate of 6/min with agonal gasps, and oxygen saturation of 82% on room air. There is no active external hemorrhage visible. She is currently lying supine on the resuscitation bay stretcher. Arrange the following critical management steps in the most appropriate sequential order for this patient's initial stabilization and triage.

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Answer

The correct sequence is: Endotracheal intubation, followed by manual leftward displacement of the uterus, administration of group O Rh-negative blood, FAST examination, and finally transport to the operating room.
The Advanced Trauma Life Support (ATLS) primary survey strictly follows the airway, breathing, and circulation algorithm. For a pregnant patient in the third trimester, specialized physiological modifications are required. This patient requires immediate airway management due to her GCS of 6 and agonal gasps. Next, her profound hemorrhagic shock must be addressed. A critical modification for pregnant trauma patients is recognizing that supine positioning causes the gravid uterus to compress the inferior vena cava, decreasing cardiac output by up to 30%. Therefore, manual left uterine displacement must be performed immediately as part of circulatory stabilization, even before or concurrently with initiating massive transfusion protocols. Because she is a female of childbearing age, uncrossmatched blood must be group O, Rh-negative to prevent alloimmunization. Only after these primary stabilization steps are initiated should secondary diagnostic adjuncts like the FAST exam be performed to locate the source of bleeding, which ultimately dictates the need for definitive operative management.

Step-by-Step Solution

1
Evaluate and secure the airway.
Endotracheal intubation is performed.
The patient has impending respiratory failure and cannot protect her airway due to a GCS of 6 and agonal respirations.
2
Relieve aortocaval compression.
Manual leftward displacement of the uterus is performed.
The supine position in the third trimester compresses the inferior vena cava, severely reducing venous return and exacerbating shock.
3
Resuscitate hemorrhagic shock.
Uncrossmatched group O, Rh-negative blood is administered.
Hemorrhagic shock in a female of childbearing age requires O-negative blood to prevent Rh sensitization while rapidly restoring oxygen-carrying capacity.
4
Identify the source of bleeding.
A FAST examination is conducted.
As an adjunct to the primary survey, bedside ultrasound quickly identifies intra-abdominal free fluid requiring surgical intervention.
5
Provide definitive surgical care.
The patient is transported to the operating room.
Refractory hemorrhagic shock with suspected internal bleeding requires immediate operative hemostasis.

Key Concept

Prioritization of trauma resuscitation in late-term pregnancy involves strict adherence to the primary survey with vital physiological modifications (Airway → Relief of aortocaval compression → Volume resuscitation → Diagnostics → Definitive Surgery).
Question 870Question →

A 68-year-old man presents to the clinic for a follow-up evaluation of an elevated prostate-specific antigen (PSA) level of 6.8 ng/mL6.8 \text{ ng/mL}. His digital rectal examination reveals a firm, non-tender nodule in the right peripheral zone of the prostate. He undergoes a transrectal ultrasound-guided core needle biopsy. The pathologist reviews the tissue cores from the right peripheral zone and reports a proliferation of small, crowded, irregularly spaced glands with scant intervening stroma. High-power magnification demonstrates cells with enlarged nuclei and prominent nucleoli. To differentiate between neoplastic and non-neoplastic processes, immunohistochemical analysis is performed. The atypical glands demonstrate a complete absence of staining for p63 and high-molecular-weight cytokeratin (HMWCK). Furthermore, the glands show strong, diffuse cytoplasmic staining for alpha-methylacyl-CoA racemase (AMACR). Based on these histopathologic and immunohistochemical findings, which of the following is the most definitive diagnosis?

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Answer: Invasive prostatic adenocarcinoma

Answer

Invasive prostatic adenocarcinoma
The correct diagnosis is invasive prostatic adenocarcinoma. The histopathologic finding of small, crowded glands with prominent nucleoli is characteristic. To definitively separate adenocarcinoma from benign mimics, immunohistochemistry is utilized. Normal prostate glands have a dual-cell layer: an inner secretory layer and an outer basal layer. Invasive prostatic adenocarcinoma is defined by the complete loss of this basal cell layer, proven by negative immunohistochemical staining for basal markers such as p63 and high-molecular-weight cytokeratin (HMWCK). Concurrently, alpha-methylacyl-CoA racemase (AMACR, also known as P504S) is highly overexpressed in prostate carcinoma cells. A profile showing p63(-)/HMWCK(-) and AMACR(+) definitively establishes the diagnosis.

Step-by-Step Solution

1
Analyze the architectural and cytologic features on the H&E stain.
The presence of small, crowded glands with scant stroma, enlarged nuclei, and prominent nucleoli raises high suspicion for malignancy.
These are the classic morphological hallmarks of prostatic adenocarcinoma.
2
Interpret the immunohistochemical stains for basal cell markers (p63 and HMWCK).
There is a complete absence of staining for p63 and high-molecular-weight cytokeratin.
Normal prostate glands and benign mimics (like BPH or adenosis) possess an intact or patchy basal cell layer. The complete loss of basal cells is the defining feature of invasive prostatic adenocarcinoma.
3
Interpret the immunohistochemical stain for AMACR (P504S).
The glands show strong, diffuse cytoplasmic staining for AMACR.
AMACR is upregulated in prostate cancer. The combination of absent basal cell markers and positive AMACR confirms the diagnosis of invasive adenocarcinoma.

Key Concept

Immunohistochemical diagnosis of prostate cancer relies on the demonstration of absent basal cells (negative p63/HMWCK) and positive expression of AMACR.
Estimated Time:1m 15s
Question 871Question →

A 42-year-old male agricultural worker is brought to the emergency department by his colleagues after collapsing in a pesticide storage facility. On arrival, he is unresponsive to verbal stimuli. He is profusely diaphoretic, vomiting, and incontinent of urine and feces. Blood pressure is 90/50 mm Hg, heart rate is 42/min, and respiratory rate is 28/min. Oxygen saturation is 84% on room air. Examination reveals bilateral pinpoint pupils and generalized muscle fasciculations. The patient has copious, frothy oral secretions and audible wheezing with poor air movement on auscultation.

Arrange the following initial stabilization and management steps in the most appropriate sequential order.

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Answer

The correct sequence of actions is: 1) Put on personal protective equipment, 2) Administer intravenous atropine, 3) Perform endotracheal intubation, and 4) Administer intravenous pralidoxime.
The patient is presenting with a classic cholinergic crisis due to organophosphate poisoning (DUMBELS mnemonic: Diaphoresis, Urination, Miosis, Bradycardia, Emesis, Lacrimation, Salivation). The immediate management of such patients requires a specific deviation from standard trauma/resuscitation algorithms. First, healthcare providers must put on PPE to avoid transdermal toxicity from the patient's contaminated clothing and skin. Second, although the patient requires airway securement, the massive amount of airway secretions (bronchorrhea) and severe bronchoconstriction make immediate endotracheal intubation virtually impossible and highly dangerous. Therefore, large doses of intravenous atropine must be administered rapidly until secretions dry up. Third, once the airway is manageable, endotracheal intubation is performed to support respiration against the nicotinic effects of diaphragmatic weakness. Finally, pralidoxime is given to regenerate the acetylcholinesterase enzyme and reverse the nicotinic blockade.

Step-by-Step Solution

1
Ensure staff safety
Providers don personal protective equipment (PPE).
Organophosphates are rapidly absorbed through the skin. Providers must protect themselves before assessing or treating the contaminated patient.
2
Clear the airway pharmacologically
Intravenous atropine is administered.
The patient's hypoxia is driven by severe bronchorrhea and bronchospasm (muscarinic effects). Atropine dries the secretions and dilates the airways, making ventilation and subsequent intubation physically possible.
3
Secure the airway mechanically
Endotracheal intubation is performed.
Once secretions are minimized, the airway must be definitively secured due to the patient's obtunded state and impending respiratory failure from nicotinic receptor overstimulation (diaphragmatic weakness).
4
Administer definitive antidote
Intravenous pralidoxime is administered.
After the primary ABCs are stabilized, pralidoxime is given to regenerate acetylcholinesterase and reverse the nicotinic symptoms (muscle fasciculations and weakness).

Key Concept

In toxicological emergencies involving organophosphates, provider safety (PPE) is paramount, and pharmacological airway clearance (Atropine) must precede mechanical airway securement (Intubation) due to massive bronchorrhea.
Estimated Time:1m 30s
Question 872Question →

A 58-year-old man with a history of poorly controlled hypertension presents to the emergency department with a sudden onset of severe, "tearing" chest pain that radiates to his back between his shoulder blades. He is diaphoretic and visibly anxious. Vital signs show a blood pressure of 190/110 mm Hg in his right arm and 150/90 mm Hg in his left arm, a heart rate of 115/min, and a respiratory rate of 22/min. Cardiac auscultation reveals a new diastolic decrescendo murmur at the right upper sternal border. An electrocardiogram shows sinus tachycardia with no ST-segment or T-wave abnormalities. A chest radiograph demonstrates a widened mediastinum. Which of the following is the most likely diagnosis?

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Answer: Acute aortic dissection

Answer

Acute aortic dissection
The correct answer is acute aortic dissection. This patient presents with the classic triad of a thoracic aortic dissection: sudden onset of tearing chest or back pain, a pulse deficit or blood pressure differential between the upper extremities, and a widened mediastinum on chest radiograph. The new diastolic murmur indicates aortic root involvement leading to acute aortic regurgitation. This is a "must-not-miss" diagnosis that requires immediate surgical or medical intervention depending on the anatomical classification (Stanford Type A vs. Type B).

Step-by-Step Solution

1
Analyze the characteristics of the patient's chest pain.
The pain is sudden, "tearing" in quality, and radiates to the back, which is highly suspicious for a vascular etiology rather than an ischemic or pulmonary one.
Characterizing the chest pain is the first step in differentiating between life-threatening causes of chest pain.
2
Evaluate the physical examination findings.
There is a significant blood pressure discrepancy between the arms (greater than 20 mm Hg systolic difference) and a new diastolic decrescendo murmur.
These findings suggest altered blood flow in the aortic arch branches (subclavian artery compromise) and acute aortic valve regurgitation, pointing to a proximal aortic dissection.
3
Interpret the diagnostic tests in the context of the clinical presentation.
The electrocardiogram is negative for acute ischemia, and the chest radiograph shows a widened mediastinum.
A widened mediastinum confirms the presence of an expanding vascular structure in the chest, definitively making acute aortic dissection the most likely diagnosis.

Key Concept

The classic presentation of acute aortic dissection includes sudden onset tearing chest pain radiating to the back, asymmetric blood pressures, and a widened mediastinum on chest radiograph.
Question 873Question →

A 7272-year-old female resident of an assisted living facility is brought to the emergency department due to acute confusion and lethargy that has worsened over the past 1212 hours. Staff report that she has had a productive cough and poor appetite for the last three days. Her medical history is significant for type 2 diabetes mellitus, hypertension, and a previous ischemic stroke with mild residual left-sided weakness. Her temperature is 39.4∘C39.4^\circ\text{C} (102.9∘F102.9^\circ\text{F}), pulse is 132132/min, blood pressure is 72/4072/40 mm Hg, and respiratory rate is 2626/min. Pulse oximetry shows 94%94\% on room air. On physical examination, she is somnolent but arouses to verbal stimuli and appropriately withdraws all four extremities from pain. Her mucous membranes are exceedingly dry, and capillary refill is delayed at 44 seconds. Lung auscultation reveals coarse crackles in the right lower lobe. Which of the following is the most appropriate initial step in the management of this patient?

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Answer: Rapid intravenous administration of a balanced crystalloid solution

Answer

Rapid intravenous administration of a balanced crystalloid solution
This patient is presenting with classic signs of septic shock, likely secondary to community-acquired pneumonia (fever, crackles, productive cough). The triad of profound hypotension, tachycardia, and poor peripheral perfusion (delayed capillary refill) indicates life-threatening circulatory failure. In the acute management of septic shock, the absolute first priority is hemodynamic stabilization to restore tissue perfusion. This is achieved by administering rapid, large-volume intravenous crystalloids (typically 3030 mL/kg within the first three hours). Once fluid resuscitation is underway, blood cultures should be drawn, broad-spectrum antibiotics administered, and the source of infection investigated. Circulatory stabilization must always take precedence over diagnostic testing.

Step-by-Step Solution

1
Evaluate the patient's vital signs and clinical presentation.
The patient demonstrates profound hypotension (72/4072/40 mm Hg), marked tachycardia (132132/min), high fever, and delayed capillary refill in the setting of a suspected lower respiratory tract infection.
Recognizing the pattern of distributive shock is required to prioritize immediate interventions over secondary diagnostic evaluations.
2
Determine the highest priority intervention according to acute resuscitation guidelines.
Hemodynamic stabilization via volume expansion is identified as the most urgent need.
In septic shock, restoring intravascular volume with rapid crystalloid administration (3030 mL/kg) is the critical first step in reversing life-threatening hypoperfusion and stabilizing the patient.

Key Concept

In patients presenting with severe sepsis or septic shock, immediate hemodynamic stabilization with rapid intravenous crystalloid fluid resuscitation must take precedence over diagnostic imaging, vasopressor initiation, and disposition changes.
Question 874Question →

A 62-year-old woman presents to the clinic for follow-up after an incidental pancreatic cystic lesion was discovered on an abdominal computed tomography (CT) scan. The initial CT was performed in the emergency department for an episode of uncomplicated diverticulitis, which has since fully resolved. She currently reports no abdominal pain, nausea, weight loss, or jaundice. Her past medical history is notable for hypertension, and she does not consume alcohol. Physical examination is unremarkable. Laboratory studies, including serum amylase, lipase, and CA 19-9, are within normal limits.

To better characterize the lesion, a magnetic resonance imaging (MRI) scan of the pancreas with magnetic resonance cholangiopancreatography (MRCP) is performed. The MRI reveals a 3.5-cm, well-circumscribed, lobulated lesion in the head of the pancreas consisting of a cluster of numerous small cysts (each less than 5 mm in diameter), creating a "honeycomb" appearance. A central stellate scar with delayed contrast enhancement is also present. There is no communication between the cystic lesion and the main pancreatic duct, and the main pancreatic duct is not dilated.

Based on the interpretation of these imaging findings, which of the following is the most appropriate next step in management?

Show answer & explanation

Answer: Routine clinical observation

Answer

Routine clinical observation is the most appropriate next step because the imaging findings are pathognomonic for a benign serous cystadenoma.
The correct answer is routine clinical observation. The patient has an incidental pancreatic cyst that is definitively identified as a serous cystadenoma (SCA) based on the MRI and MRCP interpretation.

SCAs are characterized radiographically by a well-circumscribed cluster of numerous small cysts (microcystic or "honeycomb" appearance) and a central stellate scar that often shows delayed contrast enhancement or central calcification on CT. Crucially, they do not communicate with the main pancreatic duct. SCAs are benign neoplasms with an exceedingly rare rate of malignant transformation (< 1%). Therefore, for asymptomatic patients, the standard of care is routine clinical observation. Surgical resection is indicated only if the lesion grows large enough to cause symptoms via mass effect, such as biliary obstruction or gastric outlet obstruction. Because the imaging is pathognomonic, invasive diagnostic procedures like EUS-FNA are not indicated.

Step-by-Step Solution

1
Analyze the patient's clinical presentation and laboratory results.
The patient is completely asymptomatic with a normal physical examination, normal pancreatic enzymes, and a normal CA 19-9 level.
Establishing the clinical context helps rule out acute infectious or inflammatory processes (like pseudocysts or abscesses) and lowers the pre-test probability of advanced malignancy.
2
Interpret the specific findings on the MRI/MRCP.
The lesion is microcystic (cysts < 5 mm, "honeycomb" pattern) with a central stellate scar exhibiting delayed enhancement. It does not communicate with a non-dilated main pancreatic duct.
Pancreatic cysts are differentiated primarily by their morphology (microcystic vs. macrocystic), internal structures (scars, septations, nodules), and relationship to the ductal system.
3
Synthesize the imaging interpretation to formulate a definitive diagnosis.
The combination of a microcystic architecture and a central stellate scar is pathognomonic for a serous cystadenoma.
Other cysts lack these features: mucinous cystic neoplasms are macrocystic with peripheral calcifications; IPMNs communicate with the ductal system; pseudocysts are unilocular without solid components.
4
Determine the management plan based on the established diagnosis.
Routine clinical observation without surgical intervention is selected.
Serous cystadenomas have a near-zero risk of malignant transformation. Surgical resection is reserved only for lesions causing mass effect symptoms (e.g., biliary or gastric outlet obstruction), which this patient does not have.

Key Concept

Serous cystadenomas are benign pancreatic neoplasms classically characterized on MRI by a microcystic or 'honeycomb' appearance and a central stellate scar. Because of their negligible malignant potential, asymptomatic lesions require only clinical observation.
Estimated Time:1m 15s
Question 875Question →

An 81-year-old man is evaluated in the emergency department for progressive cognitive decline and frequent falls over the past month. His daughter notes that he has become increasingly somnolent and is dragging his right leg when walking. The patient has a history of coronary artery disease and takes daily aspirin. He fell backwards and struck the back of his head on the floor five weeks ago, though he did not seek medical evaluation at the time. Vital signs are within normal limits. Neurological examination confirms a wide-based gait and mild right-sided hemiparesis. A non-contrast computed tomography (CT) scan of the head is obtained, which reveals a crescent-shaped, hypodense extra-axial fluid collection over the left frontoparietal region that freely crosses the cranial suture lines but is bounded by the dural reflections at the midline. Based on the imaging findings provided, which of the following is the most likely diagnosis?

Show answer & explanation

Answer: Chronic subdural hematoma

Answer

Chronic subdural hematoma
The correct answer is chronic subdural hematoma. The patient's presentation of progressive neurological deficits following head trauma weeks prior, combined with the CT finding of a crescent-shaped, hypodense extra-axial collection that crosses cranial suture lines, is the classic hallmark of a chronic subdural hematoma. Subdural hematomas result from the tearing of bridging veins and typically track along the contour of the brain beneath the dura mater. Over time (typically weeks), the breakdown of blood products causes the collection to appear hypodense relative to the adjacent brain parenchyma on a non-contrast CT.

Step-by-Step Solution

1
Analyze the patient's clinical history.
An elderly patient on aspirin presents with progressive cognitive decline and focal neurological deficits weeks after a minor head trauma.
To establish the clinical timeline and index of suspicion for delayed traumatic intracranial bleeding.
2
Evaluate the key imaging findings.
The head CT demonstrates a crescent-shaped, hypodense extra-axial collection that crosses cranial suture lines.
To identify the defining radiological characteristics of the lesion, which dictate the diagnosis.
3
Synthesize the findings to formulate the diagnosis.
The shape (crescentic) and boundary behavior (crosses sutures) point definitively to a subdural hematoma, while the density (hypodense) and timeline indicate a chronic process.
To rule out other types of hemorrhages (such as epidural, which are lens-shaped and bounded by sutures).

Key Concept

Interpretation of CT head imaging to differentiate intracranial hemorrhages, specifically recognizing that subdural hematomas are crescent-shaped and cross suture lines.
Estimated Time:45s
Question 876Question →

A 55-year-old man with a history of gastroesophageal reflux disease presents to the emergency department with sudden-onset, severe substernal chest pain. He reports the pain radiates to his left jaw and is accompanied by profuse sweating and nausea. He took his prescribed antacid at home 30 minutes ago without relief. An initial electrocardiogram shows normal sinus rhythm without acute ST-segment changes, and a point-of-care troponin level is within normal limits. Despite these initial test results, which of the following conditions must remain the highest priority in the differential diagnosis?

Show answer & explanation

Answer: Acute coronary syndrome

Answer

Acute coronary syndrome
The correct answer is acute coronary syndrome. The patient presents with classic features of cardiac ischemia, including substernal chest pain radiating to the jaw, accompanied by diaphoresis and nausea. A key principle in formulating a differential diagnosis is that an initial electrocardiogram and troponin level can be normal in the early stages of acute coronary syndrome (such as unstable angina or early non-ST-segment elevation myocardial infarction). Therefore, life-threatening conditions with high pre-test probability based on classic symptoms must not be prematurely removed from the differential diagnosis.

Step-by-Step Solution

1
Evaluate the patient's presenting symptoms and clinical history.
The patient exhibits classic features of cardiac ischemia, specifically substernal chest pain with radiation to the jaw, accompanied by diaphoresis and nausea.
To establish the pre-test probability of life-threatening conditions.
2
Interpret the initial diagnostic testing in the context of symptom onset.
The initial ECG and troponin are normal, which does not rule out early acute coronary syndrome or unstable angina.
Cardiac biomarkers take time to elevate, and initial ECG changes may be absent or delayed in a significant percentage of patients with myocardial infarction.
3
Formulate the highest-priority differential diagnosis.
Acute coronary syndrome remains the most critical and highly probable diagnosis that must be prioritized.
Prematurely closing the differential based on a patient's history (GERD) or early normal lab results can lead to fatal outcomes.

Key Concept

Formulating a differential diagnosis based on high pre-test probability and recognizing the limitations of early diagnostic testing in acute presentations.
Question 877Question →

A 3838-year-old female patient arrives at the acute care clinic reporting the abrupt onset of a headache that she describes as exploding in her head, reaching maximal intensity within seconds. The onset occurred two hours ago, shortly after she ingested a pseudoephedrine-based decongestant for a mild upper respiratory infection. She has a past medical history significant for major depressive disorder managed with fluoxetine.

Upon evaluation, her blood pressure is 186/104186/104 mm Hg and heart rate is 8484/min. Neurological examination demonstrates symmetric hyperreflexia in all four extremities, but no focal sensory or motor deficits, and no nuchal rigidity.

An initial unenhanced computed tomography (CT) scan of the head reveals no abnormalities. Subsequent lumbar puncture demonstrates crystal-clear fluid, opening pressure of 1616 cm H 2_2 O, 00 red blood cells/mm 3^3, 11 white blood cell/mm 3^3, and normal protein and glucose levels.

Because of persistent pain, advanced imaging is obtained. A CT angiogram of the head and neck reveals multifocal, diffuse segmental narrowing interspersed with dilated segments involving the bilateral middle and posterior cerebral arteries. A brain magnetic resonance imaging (MRI) scan shows bilaterally symmetric hyperintense areas on T2-weighted fluid-attenuated inversion recovery (FLAIR) sequences within the parieto-occipital subcortical white matter. No restricted diffusion is present.

Based on the interpretation of these imaging findings, which of the following is the most appropriate next step in the management of this patient?

Show answer & explanation

Answer: Administration of oral verapamil

Answer

The most appropriate next step in management is the administration of oral verapamil.
The patient's clinical presentation of a thunderclap headache, especially triggered by a sympathomimetic (pseudoephedrine) and an SSRI (fluoxetine), combined with the classic imaging findings, is highly diagnostic of Reversible Cerebral Vasoconstriction Syndrome (RCVS) complicated by Posterior Reversible Encephalopathy Syndrome (PRES). The CT angiogram finding of multifocal segmental narrowing and dilatation ('string of beads' appearance) confirms severe cerebral vasoconstriction. The MRI showing symmetric parieto-occipital FLAIR hyperintensities without restricted diffusion represents vasogenic edema, which is the hallmark of PRES. The most appropriate next step in management is the administration of a calcium channel blocker, such as oral verapamil or nimodipine, which directly addresses the cerebral vasospasm and helps control the elevated blood pressure.

Step-by-Step Solution

1
Analyze the clinical presentation and initial workup.
The patient has a classic thunderclap headache triggered by sympathomimetics (pseudoephedrine) and SSRIs (fluoxetine). Normal non-contrast CT and normal lumbar puncture effectively rule out subarachnoid hemorrhage (SAH).
Ruling out SAH is the mandatory first step in any thunderclap headache evaluation.
2
Interpret the advanced neuroimaging findings.
CTA demonstrates a "string of beads" (segmental narrowing and dilatation) appearance in the cerebral arteries. MRI reveals symmetric parieto-occipital FLAIR hyperintensities without restricted diffusion.
Accurate imaging interpretation distinguishes the underlying pathology from ischemic stroke, venous thrombosis, or vasculitis.
3
Synthesize the imaging results into a unifying diagnosis.
The CTA findings are pathognomonic for Reversible Cerebral Vasoconstriction Syndrome (RCVS). The MRI findings indicate vasogenic edema, confirming concomitant Posterior Reversible Encephalopathy Syndrome (PRES).
PRES frequently complicates RCVS due to the severe fluctuations in cerebral vascular tone and elevated blood pressure.
4
Select the appropriate targeted intervention.
Administration of a calcium channel blocker, such as oral verapamil or nimodipine, is indicated.
Calcium channel blockers directly treat the intense arterial vasoconstriction characterizing RCVS and assist with blood pressure control for PRES.

Key Concept

Interpretation of advanced neuroimaging to diagnose Reversible Cerebral Vasoconstriction Syndrome (RCVS) and its common complication, Posterior Reversible Encephalopathy Syndrome (PRES), distinguishing it from primary CNS vasculitis.
Estimated Time:1m 30s
Question 878Question →

A 60-year-old female undergoes an abdominal ultrasound to evaluate vague right upper quadrant discomfort. The gallbladder is normal, but the sonographer incidentally notes a 3.43.4 cm homogeneous, well-circumscribed solid mass in the left adrenal gland. The patient has no significant past medical history, no history of malignancy, and normal vital signs. Physical examination reveals no stigmata of endocrine excess. Comprehensive biochemical evaluation (including plasma free metanephrines, a 11-mg overnight dexamethasone suppression test, and an aldosterone-to-renin ratio) is entirely within normal limits. The physician decides to proceed with step-wise radiologic characterization to definitively rule out a primary adrenal malignancy.

Arrange the following imaging modalities in the correct hierarchical diagnostic sequence used to characterize an indeterminate adrenal incidentaloma, starting with the standard first-line study and progressing to advanced problem-solving modalities for persistently equivocal lesions.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct algorithmic sequence for evaluating an indeterminate adrenal incidentaloma is: Unenhanced CT (initial triage), followed by Contrast-enhanced CT with delayed washout imaging, then Chemical shift MRI, and finally 18F-FDG PET scan.
The established algorithmic approach to adrenal incidentalomas strictly prioritizes cost-effective, high-yield tests first. Unenhanced CT acts as the universal gatekeeper (lipid-rich vs. non-lipid). Adrenal protocol washout CT follows for lipid-poor lesions. Chemical shift MRI acts as a secondary problem-solving tool for indeterminate washout, and FDG-PET is reserved for highly suspicious lesions failing all prior characterization before surgery.

Step-by-Step Solution

1
Select the initial imaging study to evaluate the baseline tissue density of the mass.
Unenhanced CT of the adrenal glands.
Lipid-rich adenomas account for the vast majority of adrenal incidentalomas. An unenhanced CT showing ≤10\leq 10 HU is highly specific for a benign adenoma and requires no further workup.
2
Determine the next imaging step if the mass is dense (>10> 10 HU).
Contrast-enhanced CT with 15-minute delayed washout imaging.
Malignant lesions retain contrast, whereas benign adenomas rapidly wash out contrast. An absolute washout >60%> 60\% or relative washout >40%> 40\% diagnoses a lipid-poor adenoma.
3
Identify the problem-solving modality for lesions with indeterminate CT washout.
Chemical shift MRI.
MRI utilizes the differing resonance frequencies of protons in water and fat. A signal intensity drop on out-of-phase imaging compared to in-phase imaging definitively identifies microscopic intracellular lipid, confirming a benign etiology.
4
Select the final non-invasive imaging modality for a persistently suspicious or indeterminate mass.
18F-FDG PET scan.
If standard structural and chemical shift imaging fail to characterize the lesion, a PET scan evaluates the metabolic behavior. High FDG avidity strongly suggests adrenocortical carcinoma or metastasis, prompting surgical adrenalectomy.

Key Concept

The step-wise hierarchical imaging algorithm for characterizing adrenal incidentalomas.
Estimated Time:2m 0s
Question 879Question →

A 62-year-old man comes to the clinic reporting a 3-week history of progressively worsening shortness of breath, particularly when walking upstairs. He also reports waking up twice at night gasping for air and has noticed swelling in his ankles. He has a 10-year history of hypertension currently managed with amlodipine. Vital signs are temperature 37.0∘C37.0^\circ\text{C} (98.6∘F98.6^\circ\text{F}), blood pressure 158/92158/92 mmHg, pulse 9292/min, and respirations 1818/min. Physical examination reveals elevated jugular venous pressure, bibasilar lung crackles, and 2+ bilateral pitting pedal edema. A new S3S_3 gallop is auscultated. The physician suspects new-onset heart failure.

Which of the following diagnostic tests should be included in the initial workup for this patient? (Select all that apply)

Select all that apply

Show answer & explanation

Answer: Transthoracic echocardiography; Serum B-type natriuretic peptide (BNP) level; Thyroid-stimulating hormone (TSH) level

Answer

The correct diagnostic tests for the initial workup of this patient's suspected new-onset heart failure include transthoracic echocardiography, a serum B-type natriuretic peptide (BNP) level, and a thyroid-stimulating hormone (TSH) level.
The patient presents with classic signs and symptoms of new-onset heart failure, including paroxysmal nocturnal dyspnea, orthopnea, elevated jugular venous pressure, pulmonary crackles, pedal edema, and an S3 gallop. The appropriate initial diagnostic workup focuses on confirming the diagnosis, classifying the subtype (preserved vs. reduced ejection fraction), and identifying any reversible contributing factors using non-invasive methods. Transthoracic echocardiography is the most important initial imaging test to evaluate ventricular size, systolic/diastolic function, and valvular abnormalities. A serum B-type natriuretic peptide (BNP) or NT-proBNP level is highly sensitive and recommended to support the clinical diagnosis and provide prognostic information. Additionally, routine laboratory evaluation must include a thyroid-stimulating hormone (TSH) level, as both hyperthyroidism and hypothyroidism are common reversible causes that can precipitate or exacerbate heart failure.

Step-by-Step Solution

1
Identify the most likely diagnosis based on the clinical presentation.
The patient's dyspnea on exertion, orthopnea, lower extremity edema, elevated jugular venous pressure, bibasilar crackles, and S3 gallop strongly suggest new-onset heart failure.
Recognizing the clinical syndrome of heart failure is the critical first step in guiding appropriate diagnostic testing and sequencing.
2
Determine the recommended initial imaging and biomarker testing to confirm the diagnosis.
Transthoracic echocardiography is required to assess cardiac structure and function, while natriuretic peptide (BNP or NT-proBNP) levels help establish the diagnosis and prognosis.
These are Class I guideline-recommended initial non-invasive tests for all patients presenting with suspected new-onset heart failure.
3
Identify necessary laboratory tests to evaluate for potential contributing or reversible causes.
A TSH level is required to evaluate for occult hyperthyroidism or hypothyroidism.
A comprehensive initial evaluation must include identifying common, treatable secondary causes before pursuing more advanced or invasive diagnostic modalities.

Key Concept

The initial diagnostic workup for new-onset heart failure includes confirming the diagnosis and assessing cardiac function with non-invasive tests (transthoracic echocardiography, natriuretic peptides) while simultaneously evaluating for reversible contributing causes (TSH, complete metabolic panel, complete blood count) prior to considering any advanced or invasive testing.
Question 880Question →

A central hematopathology referral center is reviewing diagnostic material from several lymph node excisional biopsies. To establish the definitive diagnoses, correlate each hematolymphoid malignancy with its specific pathognomonic histopathologic and immunohistochemical findings.

Click a left item, then click its matching right item

Items

Follicular lymphoma
Mantle cell lymphoma
Burkitt lymphoma
Classic Hodgkin lymphoma

Matches

Show answer & explanation

Answer

Follicular lymphoma pairs with nodular architecture and BCL2 expression. Mantle cell lymphoma pairs with CD5 and Cyclin D1 expression. Burkitt lymphoma pairs with 'starry sky' morphology and a near 100% Ki-67 index. Classic Hodgkin lymphoma pairs with CD15+/CD30+ Reed-Sternberg cells.
Each hematolymphoid malignancy has a highly specific morphologic and immunophenotypic signature required for definitive diagnosis. Matching these correctly relies on recognizing the pathognomonic chromosomal translocations (e.g., t(11;14) driving Cyclin D1 in Mantle cell), unique cell morphologies (e.g., Reed-Sternberg cells in Hodgkin lymphoma), and characteristic growth patterns combined with proliferation indices (e.g., starry sky and ~100% Ki-67 in Burkitt lymphoma).

Step-by-Step Solution

1
Identify the unique diagnostic marker for Classic Hodgkin lymphoma.
The profile describing large binucleated cells that are CD15 positive and CD30 positive (Reed-Sternberg cells) corresponds to Classic Hodgkin lymphoma.
CD15 and CD30 positivity in the absence of CD20 and CD45 is pathognomonic for Classic Hodgkin lymphoma and differentiates it from non-Hodgkin lymphomas.
2
Analyze the profile with a near 100% proliferation index and 'starry sky' pattern.
This highly proliferative profile corresponds to Burkitt lymphoma.
Burkitt lymphoma is the fastest growing human tumor, characterized by a t(8;14) c-MYC translocation and extensive apoptosis with macrophage clearing, creating the starry sky appearance.
3
Differentiate between the two small/medium B-cell lymphoma profiles (Follicular vs. Mantle cell).
The profile with CD5 and Cyclin D1 positivity represents Mantle cell lymphoma. The profile with nodular architecture, CD10, and BCL2 positivity represents Follicular lymphoma.
Mantle cell lymphoma is defined molecularly by the t(11;14) translocation producing cyclin D1. Follicular lymphoma is defined by the t(14;18) translocation causing BCL2 overexpression and prevention of normal germinal center apoptosis.

Key Concept

Definitive histopathologic and immunohistochemical diagnosis of hematolymphoid malignancies.
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