Pediatrics

A 3-year-old girl is brought to the emergency department by her mother due to refusal to use her left arm. The mother reports that an hour ago, they were walking on a slippery sidewalk when the child lost her balance. To prevent her from falling to the ground, the mother instinctively pulled up firmly on the child's left hand. Following this, the child immediately began crying and has since refused to bend her elbow or reach for toys. Vital signs include a temperature of $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), pulse of $105/\text{min}$, and blood pressure of $90/60\text{ mm Hg}$. On physical examination, the child is calm when left undisturbed but holds her left arm adducted against her side with the elbow slightly flexed and the forearm pronated. There is no erythema, ecchymosis, or focal point tenderness upon palpation of the clavicle, shoulder, humerus, elbow, or wrist. As part of the initial triage protocol, point-of-care laboratory studies are obtained and reveal a leukocyte count of $7,200/\text{mm}^3$, an erythrocyte sedimentation rate of $6\text{ mm/hr}$, and a C-reactive protein of $0.3\text{ mg/dL}$. Which of the following is the most appropriate next step in management?

A 2-week-old male infant is evaluated in the pediatric orthopedic clinic for bilateral foot deformities present since birth. Physical examination reveals marked plantar flexion of the ankles, inversion of the heels, and medial deviation of the forefeet. The deformities are rigid and cannot be passively corrected to a neutral, anatomic position. Neurological examination of the lower extremities is unremarkable, and the spine is normal. A diagnosis of idiopathic congenital talipes equinovarus (clubfoot) is made, and the parents agree to proceed with the gold-standard conservative management approach. Arrange the following steps of this treatment protocol (the Ponseti method) in the most appropriate chronological order, from initial intervention to long-term maintenance.

A 4-week-old girl is brought to the pediatric emergency department for a 3-day history of a progressively weak cry, poor feeding, and decreased spontaneous movement. Her parents report she has not had a bowel movement in 5 days. They mention she has been fussy recently, and they began dipping her pacifier in local honey to soothe her. She has also had a mild cough and rhinorrhea over the past week. On physical examination, her temperature is 37.2°C (99.0°F), pulse is 150/min, and respiratory rate is 42/min. The infant exhibits generalized hypotonia, a prominent head lag, and symmetric ptosis. Gag and deep tendon reflexes are absent. Lung auscultation reveals mild, scattered end-expiratory wheezes. Skin examination shows scattered erythematous macules and papules on her cheeks, which the parents note appeared a week ago. Which of the following is the most appropriate next step in management?

A $7$-year-old boy is admitted to the pediatric intensive care unit for the initiation of chemotherapy for newly diagnosed, advanced-stage Burkitt lymphoma. He has a massive abdominal tumor burden. A central venous port was placed $48$ hours ago. Twelve hours after receiving his first dose of chemotherapy, he becomes lethargic and his urine output drops to $0.2 \text{ mL/kg/hr}$.

Continuous telemetry reveals peaked T waves and a widened QRS complex.

Temperature is $38.6^\circ \text{C}$ ($101.5^\circ \text{F}$), blood pressure is $90/55 \text{ mm Hg}$, pulse is $135/\text{min}$, and respiratory rate is $28/\text{min}$. Initial blood cultures drawn from the port at the time of admission are now growing *Escherichia coli* that is susceptible to ceftriaxone.

Laboratory studies reveal the following:

An arterial blood gas on room air shows a pH of $7.26$, $pCO_2$ of $26 \text{ mm Hg}$, and $pO_2$ of $92 \text{ mm Hg}$. Upon reviewing his chart, the parents note he missed his $4$-year-old immunization boosters and ask if they can be updated while he is hospitalized.

Which of the following is the most appropriate initial step in the management of this patient?

Match each clinical vignette with the most likely deficient enzyme.

A 6-hour-old male infant is evaluated in the neonatal intensive care unit for rapidly worsening cyanosis. He was born at 39 weeks gestation via an uncomplicated vaginal delivery to a 26-year-old primigravid woman. Vital signs demonstrate a heart rate of 175/min, a respiratory rate of 70/min, and blood pressures of 65/45 mm Hg in the right upper extremity and 63/45 mm Hg in the right lower extremity. Palpation of the peripheral arteries reveals symmetric, normal upstrokes in all four extremities. Pulse oximetry indicates an oxygen saturation of 62% despite the implementation of mechanical ventilation with a 1.0 fraction of inspired oxygen. Physical examination reveals a profoundly cyanotic, lethargic infant with prominent intercostal retractions. Cardiac auscultation demonstrates a single, loud second heart sound without any audible murmurs. A chest radiograph displays a narrowed superior mediastinum and a cardiac silhouette resembling an egg on a string, alongside mildly increased pulmonary vascular markings. A continuous infusion of a prostaglandin analog is initiated immediately; however, 30 minutes later, the infant's oxygen saturation remains at 64% and an arterial blood gas reveals a pH of 7.21, pCO2 of 42 mm Hg, and pO2 of 26 mm Hg. Which of the following interventions should be prioritized next for this patient?

A 6-month-old male infant is brought to the emergency department by his parents due to repetitive, profuse vomiting and extreme lethargy. The vomiting began approximately 2 hours after he was fed oat cereal for the first time. The parents note that he became remarkably pale and limp shortly after the vomiting started. He was born at term and has previously tolerated breast milk and pureed vegetables without issue. His temperature is 36.5°C (97.7°F), heart rate is 185/min, blood pressure is 60/35 mmHg, and respiratory rate is 45/min. Physical examination reveals a lethargic, mottled infant with delayed capillary refill of 5 seconds. There is no rash, urticaria, or facial swelling. The lungs are clear to auscultation bilaterally without wheezing. The abdomen is soft, non-distended, and non-tender, with hyperactive bowel sounds.

Laboratory studies show:
Leukocyte count: $24,500/\text{mm}^3$ (with 18% bands)
Hemoglobin: $11.5 \text{ g/dL}$
Platelets: $550,000/\text{mm}^3$
Arterial blood gas:
pH: $7.28$
$pCO_2$: $35 \text{ mm Hg}$
$HCO_3^-$: $16 \text{ mEq/L}$

Which of the following is the most appropriate initial management for this patient?

Match each classic pediatric clinical presentation with the most likely underlying gastrointestinal diagnosis.

Match each pediatric patient's clinical and laboratory presentation to the most likely underlying endocrine disorder.

Match the following pediatric hematologic malignancies with their characteristic molecular, cytogenetic, or immunophenotypic findings.

A male newborn is evaluated in the neonatal intensive care unit $2$ hours after birth for rapid breathing. The infant was delivered at $38$ weeks gestation via elective cesarean delivery to a $28$-year-old primigravid woman. The mother's pregnancy was uncomplicated, and she did not experience labor prior to the procedure. Her group B Streptococcus screen was negative at $36$ weeks. The infant's Apgar scores were $8$ and $9$ at $1$ and $5$ minutes, respectively. Currently, the infant's temperature is $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), heart rate is $150$/min, and respiratory rate is $74$/min. Pulse oximetry is $91\%$ on room air. Physical examination reveals nasal flaring and mild intercostal retractions. Lung auscultation demonstrates clear breath sounds bilaterally without murmurs. A chest radiograph reveals hyperinflation, prominent perihilar vascular markings, and fluid in the interlobar fissures. Which of the following is the most appropriate next step in the management of this patient?

A 4-year-old boy of East Asian descent is admitted to the pediatric ward with a 6-day history of persistent fever measuring up to $39.8^\circ\text{C}$ ($103.6^\circ\text{F}$). His parents report that he has been highly irritable and refuses to eat. On physical examination, the child is tachycardic but normotensive. He has bilateral nonexudative conjunctival injection, cracked and fissured lips, a prominent 'strawberry tongue,' and tender cervical lymphadenopathy. Erythema and edema of the dorsal hands and feet are noted, along with a polymorphous maculopapular rash over the trunk. A baseline transthoracic echocardiogram obtained upon admission shows structurally normal coronary arteries. He is diagnosed with classic Kawasaki disease.

Arrange the following management and follow-up steps in the correct chronological sequence for this patient, starting with immediate inpatient treatment and concluding with long-term outpatient preventive care.

A 4-year-old girl is brought to the pediatric emergency department with a 2-day history of high fever, severe headache, and vomiting. Over the last 6 hours, she has become increasingly lethargic. Her temperature is 39.5°C (103.1°F), heart rate is 145/min, blood pressure is 112/68 mmHg, and respiratory rate is 26/min. On physical examination, she is difficult to arouse. She exhibits marked nuchal rigidity and a newly appreciated right-sided abducens nerve (cranial nerve VI) palsy. The remainder of the neurologic examination is limited by her somnolence but shows symmetric withdrawal to pain.

Arrange the following diagnostic and therapeutic steps in the most appropriate sequential order for managing this patient.

Parents bring their 24-month-old son to the outpatient clinic after noticing a large amount of maroon-colored stool in his diaper earlier today. The child has no history of fever, abdominal pain, diarrhea, or vomiting. He is currently playing comfortably in the examination room. Vital signs show a heart rate of 105/min, respiratory rate of 24/min, and blood pressure of 90/55 mm Hg. Physical examination reveals a soft, non-tender abdomen with normal active bowel sounds and no palpable masses. Inspection of the perianal area shows no fissures, but residual maroon-colored stool is present on the examining glove. Which of the following is the most appropriate next diagnostic step to establish the underlying cause of this patient's bleeding?

Paramedics bring a 14-day-old infant to the emergency department due to severe lethargy, poor feeding, and mottled skin. On physical examination, the infant has a depressed level of consciousness and is in marked respiratory distress with grunting and severe subcostal retractions. Capillary refill time is 6 seconds. Vital signs show a heart rate of 195/min, respiratory rate of 75/min, and oxygen saturation of 89% on room air. Palpation of the extremities reveals bounding brachial pulses and imperceptible femoral pulses. Arterial blood gas analysis demonstrates severe uncompensated metabolic acidosis. Arrange the following clinical interventions and diagnostic steps in the most appropriate chronological sequence for managing this patient.

A 5-day-old male infant is brought to the emergency department by his parents due to 24 hours of decreased feeding, progressive lethargy, and recurrent vomiting. He was born full-term via an uncomplicated vaginal delivery and was discharged home on day 2 of life. The infant is exclusively breastfed. Vital signs show a temperature of 36.2°C (97.2°F), heart rate of 175/min, and respiratory rate of 68/min. On physical examination, the infant is somnolent with diffuse hypotonia and deep, rapid breathing. Laboratory results are as follows:

Urinalysis is strongly positive for ketones. Deficient activity of which of the following enzymes is the most likely cause of this patient's condition?

During a scheduled health maintenance visit, the parents of an $8$-year-old girl express concern about her recent rapid growth and the development of severe facial acne. Over the past eight months, she has required frequent shoe size changes, and her height has crossed from the $50$ th to the $90$ th percentile. The parents also report the onset of adult-type body odor and the appearance of dark, coarse pubic hair. She has not developed any breast tissue and has not had vaginal bleeding. On physical examination, her blood pressure is $102/64 \text{ mm Hg}$ and heart rate is $82/\text{min}$. Genitourinary examination reveals Tanner stage $3$ pubic hair and mild clitoromegaly. There are no palpable abdominal or pelvic masses. A radiograph of the left hand and wrist demonstrates a skeletal bone age of $11$ years. Which of the following is the most appropriate next step in the evaluation of this patient?

A 2-year-old child is brought to the emergency department after passing a massive volume of painless, dark red stool at home. On examination, the patient appears pale, mottled, and lethargic. Vital signs reveal a heart rate of 165/min, respiratory rate of 28/min, and blood pressure of 70/40 mmHg. Capillary refill time is prolonged at 4 seconds. The abdomen is soft, non-distended, and non-tender to palpation. Arrange the following medical interventions in the most appropriate chronological sequence for the evaluation and management of this patient.

Parents of an infant currently aged 6 months bring him to the urgent care clinic. They report that he recently began having clusters of sudden, symmetric forward bending of his head and torso, along with extension of his arms. These spells primarily happen just as he is waking up. During the physical examination, the physician notes the presence of three distinct, ash-leaf shaped hypopigmented macules on the infant's trunk. Arrange the following interventions in the most appropriate chronological sequence for evaluating and managing this patient's condition.

An $18$-month-old boy is brought to the pediatric clinic by his parents due to a persistent cough for the past $3$ weeks. The parents state the cough began suddenly while he was eating mixed nuts at a family gathering. He coughed vigorously for a few minutes, but the choking episode seemingly resolved. Over the following weeks, he developed a daily, harsh cough. He was evaluated at an urgent care center two weeks ago and completed a $10$-day course of high-dose oral amoxicillin for suspected community-acquired pneumonia, but his symptoms have not improved. Today, his temperature is $37.2^\circ\text{C}$ ($99.0^\circ\text{F}$), pulse is $120/\text{min}$, respirations are $28/\text{min}$, and oxygen saturation is $96\%$ on room air. Physical examination reveals diminished breath sounds and localized, monophonic expiratory wheezing over the right lower lung field. The left lung field is clear to auscultation. A chest radiograph reveals volume loss in the right lower lobe with no radiopaque structures visualized. Which of the following is the most appropriate next step in management?