Pediatrics

A variety of pediatric musculoskeletal conditions present with distinct physical examination signs or characteristic resting postures. Match each specific clinical examination finding with the most appropriate underlying diagnosis.

Correlate the following pediatric hematology and oncology conditions with their characteristic microscopic, histologic, or laboratory hallmarks.

An 11-year-old boy is brought to the emergency department by his parents after he fainted during a soccer game. Over the past three months, he has experienced worsening fatigue, unexplained weight loss, and recurrent episodes of vague abdominal pain and nausea. His parents mention that he has developed an intense craving for salty foods. On physical examination, his temperature is $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), blood pressure is $82/50\text{ mmHg}$ while supine and drops to $68/40\text{ mmHg}$ upon standing, and pulse is $115\text{/min}$. He appears lethargic. There is noticeable darkening of the skin, particularly over the palmar creases, elbows, knees, and buccal mucosa.

Initial laboratory evaluation reveals:
Serum sodium: $128\text{ mEq/L}$
Serum potassium: $6.1\text{ mEq/L}$
Serum chloride: $95\text{ mEq/L}$
Serum bicarbonate: $16\text{ mEq/L}$
Blood urea nitrogen: $26\text{ mg/dL}$
Serum creatinine: $0.9\text{ mg/dL}$
Serum glucose: $58\text{ mg/dL}$

Which of the following pairs of baseline hormone levels is most likely to be present in this patient prior to any intervention?

A 12-month-old boy is brought to the pediatric emergency department by his parents after a witnessed episode of generalized tonic-clonic movements lasting for 2 minutes. The episode occurred 45 minutes ago, and the child is now sleepy but easily arousable. He has no history of fever, trauma, or previous seizures. Vital signs are temperature 37.1°C (98.8°F), heart rate 110/min, respiratory rate 24/min, and blood pressure 90/55 mmHg. Physical examination reveals seven well-demarcated, flat, hyperpigmented macules measuring between 8 and 12 mm across his trunk and extremities, as well as distinct freckling in the bilateral axillary regions. Neurologic examination shows a drowsy child with normal muscle bulk and tone, moving all extremities equally. The parents mention they have been worried about his development recently because he only cruises along furniture and says "mama" and "dada" specifically, though he uses a mature pincer grasp.

Based on this patient's clinical presentation, which of the following statements regarding his evaluation and management are correct? (Select all that apply)

During a routine assessment in the newborn nursery, a 2-day-old female infant is found to have central cyanosis that worsens when she cries. She was delivered vaginally at 39 weeks gestation following an uncomplicated pregnancy. Vital signs include a heart rate of 158/min, respiratory rate of 55/min, and blood pressure of 68/40 mm Hg in the right arm. Pulse oximetry indicates an oxygen saturation of 76% on room air. After administration of 100% supplemental oxygen for 10 minutes, her saturation marginally improves to 78%. Physical examination confirms bluish discoloration of the perioral area and mucous membranes. Cardiac auscultation reveals a normal S1, a loud and single S2, and a grade 3/6 holosystolic murmur at the left lower sternal border. An electrocardiogram demonstrates left axis deviation, small R waves in the right precordial leads, and tall P waves in lead II. Chest radiography reveals a normal cardiac size with diminished pulmonary vascular markings. Which of the following is the most likely diagnosis?

A 7-month-old boy is brought to the emergency department in mid-January with a 3-day history of worsening respiratory distress. He was born at 39 weeks gestation and has no significant past medical history. The illness began with rhinorrhea, low-grade fever, and a mild cough. The patient's mother has a history of severe persistent asthma and wonders if he needs her 'breathing treatments.'

Upon arrival, vital signs show:
* Temperature: $38.3^\circ\text{C}$ ($100.9^\circ\text{F}$)
* Heart rate: $182/\text{min}$
* Respiratory rate: $74/\text{min}$
* Oxygen saturation: $86\%$ on room air

Physical examination reveals an anxious, tachypneic infant with marked head bobbing, severe subcostal retractions, and nasal flaring. Lung auscultation demonstrates diffuse polyphonic wheezing, a markedly prolonged expiratory phase, and scattered bibasilar crackles.

Laboratory and radiographic findings:
* Leukocyte count: $11,800/\text{mm}^3$ ($68\%$ lymphocytes, $25\%$ neutrophils)
* Capillary blood gas (room air): $\text{pH} = 7.30$, $\text{pCO}_2 = 60\text{ mm Hg}$
* Chest radiograph: Bilateral pulmonary hyperinflation, flattened hemidiaphragms, and extensive peribronchial thickening without distinct lobar consolidation.

Which of the following interventions MUST be included in the evidence-based acute management bundle for this patient? (Select exactly 2 interventions)

A $5$-day-old male neonate is brought to the pediatric emergency department by his parents due to extreme lethargy, poor feeding, and rapid, labored breathing that has worsened over the past $12$ hours. The infant was born at $39$ weeks gestation via an uncomplicated vaginal delivery and was discharged home on day two of life. On physical examination, the infant appears mottled and pale. His temperature is $36.4^\circ\text{C}$ ($97.5^\circ\text{F}$), heart rate is $192/\text{min}$, respiratory rate is $75/\text{min}$, and blood pressure is $68/40 \text{ mm Hg}$ in the right arm and $45/25 \text{ mm Hg}$ in the left leg. Capillary refill time is $6$ seconds. Palpation of the extremities reveals bounding right brachial pulses, but the femoral and dorsalis pedis pulses are barely palpable. Pulse oximetry on room air is $96\%$ on the right hand and $86\%$ on the right foot. Lung auscultation reveals bilateral crackles. Hepatomegaly is noted $3\text{ cm}$ below the right costal margin. An arterial blood gas analysis demonstrates a $pH$ of $7.12$, $pCO_2$ of $29 \text{ mm Hg}$, and $HCO_3^-$ of $10 \text{ mEq/L}$. Which of the following is the most appropriate initial step in the management of this patient?

An anxious mother brings her 5-week-old firstborn son to the pediatrician's office because he has been vomiting for the past five days. She notes that the vomiting occurs immediately after every feeding, is very forceful, and consists of curdled breast milk without any green or yellow discoloration. Despite the vomiting, the infant cries continuously and appears ravenously hungry, eagerly demanding to be fed again. On physical examination, the infant has slightly dry mucous membranes and a sunken anterior fontanelle. Palpation of the abdomen reveals a firm, mobile, 2-cm ovoid mass in the right upper quadrant. Which of the following is the most appropriate initial diagnostic test to confirm this patient's underlying condition?

A 7-year-old girl is brought to the emergency department with severe respiratory distress. She has a history of moderate persistent asthma and has been using her albuterol inhaler every 2 hours at home without relief. On presentation, she is alert but anxious, speaking in single words. Vital signs show a respiratory rate of 42/min, heart rate of 150/min, and oxygen saturation of 88% on room air. Examination reveals diffuse inspiratory and expiratory wheezes with prominent suprasternal retractions. Arrange the following interventions in the most appropriate sequential order of escalation for managing this patient's acute severe asthma exacerbation, from initial presentation to refractory respiratory failure.

An 8-month-old infant, recently immigrated from a rural region without a universal newborn screening program, is brought to the pediatric clinic for evaluation of developmental delay. The parents report that the infant has not yet started to sit unsupported, roll over, or babble. On physical examination, the infant has noticeably lighter skin and hair pigmentation compared to both biological parents, a diffuse eczematous rash on the flexor surfaces, and a distinct 'musty' body odor. A presumptive diagnosis of a metabolic disorder is made. Arrange the following steps in the most appropriate chronological sequence for the comprehensive evaluation and lifespan management of this patient's condition, from the immediate next diagnostic step to adulthood.

Emergency medical services arrive with a 7-year-old male who has homozygous sickle cell disease (HbSS). His parents report that he abruptly developed right arm paralysis and lost the ability to speak approximately 45 minutes ago. His temperature is $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), blood pressure is $112/72 \text{ mm Hg}$, pulse is $118\text{/min}$, and respirations are $22\text{/min}$. Oxygen saturation is $98\%$ on room air. Neurological examination reveals a right-sided facial droop, expressive aphasia, and $2/5$ muscle strength in the right upper and lower extremities. Laboratory studies show a hemoglobin of $7.5 \text{ g/dL}$, hematocrit of $22\%$, and a reticulocyte count of $12\%$. Arrange the following steps in the most appropriate chronological sequence for the comprehensive immediate and long-term management of this patient.

A 3-week-old boy is admitted to the neonatal intensive care unit after experiencing two episodes of rhythmic twitching of his right arm and leg, each lasting approximately one minute. He was born at term via uncomplicated spontaneous vaginal delivery to a 28-year-old primigravida. His prenatal course was unremarkable. On physical examination, the neonate is afebrile and vital signs are stable. He alerts to loud sounds and briefly tracks his mother's face. Examination of the skin reveals scattered erythematous macules with central 1-2 mm yellowish pustules over his trunk and face. A magnetic resonance imaging (MRI) scan of the brain demonstrates restricted diffusion in the left middle cerebral artery territory, consistent with an acute ischemic stroke. When discussing the patient's condition and expected care plan with the parents, which of the following statements are correct? (Select all that apply)

A $12$-year-old girl with a history of cystic fibrosis presents to the emergency department with a $1$-week history of increased cough, purulent sputum production, fatigue, and a $2\text{-kg}$ ($4.4\text{-lb}$) weight loss. She reports a decreased appetite but no fever. Her baseline $\text{FEV}_1$ is $75\%$ of predicted, but today it is $55\%$. Vital signs are temperature $37.4^\circ\text{C}$ ($99.3^\circ\text{F}$), heart rate $110/\text{min}$, respiratory rate $24/\text{min}$, and blood pressure $110/70\text{ mm Hg}$. Oxygen saturation is $93\%$ on room air. Physical examination reveals coarse crackles scattered throughout both lung fields. Sputum cultures from a routine clinic visit $1$ month ago grew *Pseudomonas aeruginosa* and *Staphylococcus aureus*. Which of the following are the most appropriate initial steps in the management of this patient's acute pulmonary exacerbation? (Select all that apply)

During a pediatric gastroenterology case conference, a series of complex patient presentations is reviewed. For each atypical or highly specific clinical vignette described below, identify the correct underlying embryologic or pathophysiologic mechanism.

A $15$-month-old boy is brought to the pediatric clinic by his paternal grandmother for a routine evaluation. She expresses significant concern regarding the child's "curved legs" and insists that he requires immediate corrective casting to prevent permanent deformity. The patient's mother, who has sole legal custody and is accessible via phone, previously discussed this finding with the physician and stated she is comfortable with conservative observation. The child began walking independently at $12$ months of age and is currently acquiring new vocabulary. His diet is well-balanced and includes fortified whole milk and a daily multivitamin. Vital signs are within normal limits. Physical examination reveals a happy, well-appearing toddler with symmetric bilateral genu varum (bowlegs). There is no localized tenderness, erythema, or leg-length discrepancy. His gait is steady without limping. A basic metabolic panel, serum calcium, phosphorus, thyroid-stimulating hormone (TSH), and free T4 are all within normal limits. Which of the following is the most appropriate next step in management?

A 9-year-old boy is evaluated in the pediatric endocrinology clinic for new-onset severe polyuria, polydipsia, and nocturia over the past month. He is otherwise healthy, and a recent comprehensive metabolic panel and hemoglobin A1c were within normal limits, ruling out diabetes mellitus. The physician suspects diabetes insipidus and admits the patient to the hospital for a water deprivation test. Arrange the following steps in the correct chronological sequence for performing this diagnostic test.

During a scheduled wellness visit, the parents of a 4-month-old infant express concern regarding their child's breathing. They describe a high-pitched 'squeaking' sound when the baby inhales, which they first noticed around 4 weeks of age. The noise becomes significantly louder when the infant is crying or placed on his back to sleep. Conversely, the parents note the sound almost completely disappears when the baby is resting on his stomach. He is exclusively breastfed, feeds well without cyanosis or choking, and is tracking along the 50th percentile for both length and weight. His temperature is 37.0°C (98.6°F), pulse is 120/min, and respirations are 30/min. Physical examination reveals an alert, well-nourished infant with prominent inspiratory stridor that worsens in the supine position. Which of the following is the most likely underlying cause of this patient's clinical presentation?

A $10$-month-old male infant is currently hospitalized on the pediatric ward. He was admitted $3$ days ago for severe respiratory syncytial virus (RSV) bronchiolitis requiring heated humidified high-flow nasal cannula. On hospital day $2$, he developed a temperature of $39.5^\circ\text{C}$ ($103.1^\circ\text{F}$), worsening hypoxemia, and new focal crackles in the left lower lung field. Chest radiography confirmed a new left lower lobe consolidation. Blood cultures were drawn, and empiric intravenous ceftriaxone was initiated for suspected secondary bacterial pneumonia. Today (hospital day $4$), he has been afebrile for $24$ hours and is weaning off respiratory support. Physical examination reveals scattered expiratory wheezing and mild intercostal retractions. The blood culture drawn on day $2$ is now positive for *Streptococcus pneumoniae*. Antimicrobial susceptibility testing indicates the isolate is susceptible to penicillin, ampicillin, ceftriaxone, and vancomycin. Which of the following is the most appropriate modification to this patient's treatment plan?

A 6-year-old girl is brought to the emergency department by her parents due to a sudden onset of fever. She was diagnosed with acute lymphoblastic leukemia (ALL) six months ago and is currently undergoing maintenance chemotherapy. Her temperature is $39.4^\circ C$ ($102.9^\circ F$), blood pressure is $90/55$ mmHg, and heart rate is $125$/min. Physical examination reveals a pale, fatigued child with a central venous catheter in place. There is no erythema or discharge at the catheter site. Laboratory studies show an absolute neutrophil count (ANC) of $350/mm^3$. Blood cultures are obtained. Which of the following is the most appropriate next step in management?

A 6-week-old female infant is brought to the clinic for a well-child visit. Her parents report that she is exclusively breastfed and feeding well, but they have noticed her skin appearing increasingly yellow over the past two weeks. Additionally, her stools have recently become very pale, resembling the color of clay. Physical examination is notable for scleral icterus, generalized jaundice, and a palpable liver edge 2 cm below the right costal margin. Arrange the following steps in the most appropriate chronological sequence for the standard evaluation and definitive management of this patient's suspected condition.