pediatrics

Question 1

Chronic granulomatous disease

Answer 1

Pathogenesis

X-linked recessive mutation of NADPH oxidase
Impaired respiratory burst & ↓ reactive oxygen species → inhibition of phagocytic intracellular killing
Clinical features

Recurrent infections with catalase-positive* bacteria & fungi
Lungs, skin, liver, lymph node involvement
Diffuse granulomas (eg, gastrointestinal, genitourinary)
Diagnosis

Measurement of neutrophil superoxide production:
DHR flow cytometry (preferred)
NBT testing
Treatment

Prophylaxis: TMP-SMX, itraconazole, interferon gamma
Active infection: culture-based, antimicrobial therapy
Hematopoietic cell transplant is curative

Question 2

Preseptal vs orbital cellulitis

Answer 2

Preseptal cellulitis

Orbital cellulitis

Clinical features

Eyelid erythema & swelling
Chemosis
Symptoms of preseptal cellulitis
PLUS

Pain with EOM, proptosis &/or ophthalmoplegia with diplopia
Treatment

Oral antibiotics
Intravenous antibiotics
± Surgery

Question 3

Causes of stridor in infants & toddlers

Answer 3

Acute

Croup

Parainfluenza virus, most cases in fall/winter
Inspiratory or biphasic stridor, “barky” cough, infectious symptoms
Foreign body aspiration

± Choking episode
Inspiratory stridor &/or wheeze, focally diminished breath sounds
Chronic

Laryngomalacia

“Floppy” supraglottis, prominent age 4-8 months
Inspiratory stridor worsens when feeding, crying, or supine; improves when prone
Vascular ring

Great vessels encircle & compress trachea
Biphasic stridor that improves with neck extension
Airway hemangioma

Hemangiomas enlarge in the first few weeks of life
Worsening biphasic stridor, concurrent skin hemangiomas (“beard distribution”)

Question 4

Neonatal indirect hyperbilirubinemia

Answer 4

↑ Bilirubin production

Immune-mediated hemolysis (Coombs positive)
Rh isoimmunization
ABO incompatibility
Nonimmune-mediated hemolysis (Coombs negative)
RBC membrane defects (eg, spherocytosis)
RBC enzyme defects (eg, G6PD deficiency)
Cephalohematoma
Polycythemia

↓ Bilirubin clearance

Gilbert syndrome
Crigler-Najjar syndrome

↑ Enterohepatic circulation

Lactation failure jaundice
Breastmilk jaundice

Question 5

An 8-year-old boy is brought to the clinic for evaluation of a limp. The patient first noticed a mild ache in his upper right thigh 6 days ago. The pain is worse in the evening and improves after sleep. He does not recall an injury but notes that the pain started after returning from a weeklong camping trip. His group went hiking each day of the trip except for 2 days in the middle, during which some campers, including the patient, were experiencing vomiting and diarrhea. He had a similar pain in his left thigh 6 months ago, which resolved after a few days. The patient is otherwise healthy and takes no medications. Temperature is 37.8 C (100 F). He bears little weight on his right leg while walking. There is no gross abnormality or tenderness along the thigh. While supine, the patient holds the right hip slightly flexed, resisting extension and internal rotation. Skin examination is normal. Laboratory evaluation reveals a leukocyte count of 8,000/mm3 and erythrocyte sedimentation rate of 10 mm/h. Ultrasound of the right hip shows a small intracapsular fluid collection. Which of the following is the best pharmacotherapy for this patient?

A.Doxycycline

B.Ibuprofen

C.Methotrexate

D.Metronidazole

E.Vancomycin

Answer 5

Transient synovitis

Epidemiology

Age 3-8
Preceding viral illness
Clinical features

Well-appearing, afebrile, or low-grade fever
Limp (able to bear weight on affected leg)
Hip pain (mildly restricted ROM)
Diagnosis

Normal (or minimally elevated) WBC count, ESR, CRP
Small effusions on ultrasound
Management

Conservative
Nonsteroidal anti-inflammatory drugs
Prognosis

Full recovery within 1-2 weeks
Recurrence uncommon

Question 6

A 1-hour-old boy is evaluated for respiratory distress. The patient was born at 39 weeks gestation via cesarean delivery. The mother’s pregnancy was complicated by gestational diabetes, and she was nonadherent with treatment. Birth weight was at the 95th percentile. Apgar scores were 5 and 7 at 1 and 5 minutes, respectively. Temperature is 36.6 C (97.9 F), pulse is 160/min, and respirations are 70/min. Oxygen saturation is 94% on room air. The patient is in mild respiratory distress with a plethoric appearance. Cardiac examination reveals a 3/6 systolic ejection murmur. Physical examination is otherwise unremarkable. Bedside echocardiography shows increased thickness of the interventricular septal wall. Which of the following is the best initial therapy for this patient?

A.Dobutamine

B.Furosemide

C.Indomethacin

D.Nitroprusside

E.Propranolol

Answer 6

Hypertrophic cardiomyopathy in infants of diabetic mothers

Pathogenesis

Maternal hyperglycemia → fetal hyperglycemia & hyperinsulinemia
↑ Glycogen & fat deposition in interventricular septum → dynamic LVOT obstruction
Clinical findings

Often asymptomatic
May have respiratory distress and/or hypotension
Systolic ejection murmur
Imaging

Chest x-ray: cardiomegaly
Echocardiogram: ↑ thickness of interventricular septum, ↓ LV chamber size
Treatment

Intravenous fluids & beta blockers to increase LV blood volume
Prognosis

Spontaneous regression by age 1

Question 7

A 12-year-old girl is brought to the emergency department due to episodes of anxiety, tachycardia, and diaphoresis. She has been sleeping poorly for the last 2 weeks and has developed a desquamating rash, which her mother attributes to profuse sweating. The patient has elevated urinary catecholamines; however, extensive evaluation for pheochromocytoma is unrevealing. Measuring levels of which of the following substances is the best next step in management of this patient?

A.Aluminum

B.Copper

C.Iron

D.Mercury

E.Zinc

Answer 7

Chronic mercury toxicity

Exposures

Incidental (eg, broken lightbulbs or thermometers)
Ingestion (eg, shark, swordfish)
Occupational
Clinical features*

Neuropsychiatric: tremor, insomnia, personality changes (eg, irritability)
Cardiovascular: hypertension, tachycardia
Mucocutaneous: gingivitis; diaphoresis; swelling, redness, desquamation of hands/feet
Renal: tubular damage/proteinuria

Question 8

An 8-year-old girl is brought to the office due to involuntary movements of the hands and body for a week. The movements get worse when the patient feels anxious, and she cannot suppress them. She has also had an urge for frequent hand cleaning. Vital signs are normal. On examination, the patient has inappropriate laughing and frequent throat clearing. The tonsils are enlarged and hyperemic. Neurologic examination shows generalized, involuntary movements of the body. Grip strength is strong; however, the patient cannot maintain it because of irregular hand and arm movements. Cranial nerve, sensation, and mental status examinations show no abnormalities. Complete blood count, serum chemistries, and liver function studies are normal. What is the most likely cause of this patient’s symptoms?

A.Basal ganglia atrophy

B.Defective hepatic copper excretion

C.Degeneration of motor neurons

D.Degeneration of the cerebral cortex

E.Molecular mimicry

Answer 8

Sydenham chorea

Pathophysiology

Preceding GAS infection
Molecular mimicry between anti-GAS antibodies & neuronal antigens in basal ganglia
Clinical features

Involuntary, jerky movements (worse while awake & with action)
Hypotonia
Emotional lability, obsessive-compulsive behaviors
± Symptoms of acute rheumatic fever
Evaluation

GAS testing: throat culture, ASO & anti-DNAse B titers
Cardiac testing: echocardiography, ECG
Treatment

Chronic antibiotics (eg, penicillin G)
Symptomatic (antidopaminergics [eg, haloperidol])
Prognosis

Spontaneous remission
Recurrence common
↑ Risk of rheumatic heart disease

Question 9

Lactation failure jaundice

Answer 9

Age <1 week

Insufficient intake of breast milk:

↓ Bilirubin elimination
↑ Enterohepatic circulation
Suboptimal breastfeeding

Question 10

Acute otitis media

Answer 10

Microbiology

Streptococcus pneumoniae
Nontypeable Haemophilus influenzae
Moraxella catarrhalis
Clinical
features

Bulging TM
Middle ear effusion plus TM inflammation (eg, fever, otalgia, erythema)
Treatment

Initial: amoxicillin
2nd-line: amoxicillin-clavulanate
Penicillin-allergic: clindamycin or azithromycin
Complications

TM perforation
Conductive hearing loss
Mastoiditis
Meningitis

Question 11

An 8-year-old girl is brought to the emergency department with lethargy and fever. The patient has had intermittent cough, fever, and headache for the past 3 weeks. She vomited before dinner last night and went to bed early. This morning, her father could not wake her up. The patient is otherwise healthy. She traveled with her family to rural Ecuador 2 months ago for a mission trip. She has no other recent travel and no known sick contacts. Temperature is 39.8 C (103.6 F). The patient is minimally responsive on examination. Funduscopy shows papilledema, and chest auscultation reveals decreased breath sounds and crackles over the right middle lobe. The results of lumbar puncture are as follows:

Glucose 6 mg/dL
Protein 110 mg/dL
Leukocytes 230/mm3
Neutrophils 20%
Lymphocytes 70%
Monocytes 10%
Which of the following organisms is the most likely cause of this patient’s symptoms?

A.Aspergillus fumigatus

B.Enterovirus

C.Listeria monocytogenes

D.Mycobacterium tuberculosis

E.Streptococcus pneumoniae

F.Toxoplasma gondii

Answer 11

Tuberculous meningitis

Pathophysiology

Hematogenous spread of Mycobacterium tuberculosis to subarachnoid space
Most commonly presents 2-6 months after primary infection
Clinical
manifestations

Stage 1: several weeks of nonspecific fever, headache, drowsiness
Stage 2: overt meningitis with lethargy, nuchal rigidity, vomiting, cranial nerve palsies, or other focal neurologic signs
Stage 3: coma, herniation, death
Diagnosis

CSF lymphocytic pleocytosis, ↑ protein, ↓ glucose
Positive acid-fast bacillus culture or PCR test from CSF
Tuberculin skin testing or interferon-gamma release assay may be falsely negative
Treatment

Combination antimycobacterial therapy
Glucocorticoids to reduce CNS swelling

Question 12

Congenital hypothyroidism

Answer 12

Clinical
manifestations

Usually asymptomatic at birth (rarely causes delayed meconium passage)
After maternal thyroxine wanes (weeks to months)
Lethargy, poor feeding
Enlarged fontanelle
Protruding tongue, puffy face, umbilical hernia
Constipation
Prolonged jaundice
Dry skin
Diagnosis

↑ TSH & ↓ free thyroxine levels
Newborn screening
Treatment

Levothyroxine*
Prognosis

No deficits if treatment started in neonatal period
Untreated disease is associated with neurocognitive dysfunction (eg, ↓ intelligence quotient)

Question 13

A 5-day-old girl is brought to the emergency department due to fussiness. The patient was born at home to a 36-year-old woman, gravida 5 para 5, via spontaneous vaginal delivery. The mother received no prenatal care. The newborn has been breastfeeding exclusively and has had nonbloody, nonbilious vomiting after feeds for the past day. Head circumference and length are at the 50th percentile. Weight is at the 20th percentile. Temperature is 37.2 C (99 F) and pulse is 180/min. The newborn has poor tone and is jaundiced. The anterior fontanelle is sunken with overriding sutures. Eye examination shows bilateral cataracts. Ears are in the normal position, and the palate is intact with a normal tongue. Cardiopulmonary examination is normal. The liver is palpable 4 cm below the costal margin. Which of the following is the most likely cause of this newborn’s presentation?

A.Advanced maternal age

B.In utero fetal alcohol exposure

C.Maternal nonadherence to vaccination schedule

D.Newborn inability to metabolize breast milk

E.Newborn inherited muscle dystrophy

Answer 13

Galactosemia

Etiology

GALT deficiency
Autosomal recessive
Galactose accumulation after lactose or galactose ingestion
Clinical findings

Jaundice & hepatomegaly
Vomiting & poor feeding/failure to thrive
Cataracts
Increased risk for Escherichia coli sepsis
Laboratory findings

↑ Bilirubin, AST, ALT
↓ Glucose
Metabolic acidosis
+ Urine reducing substance
Diagnosis

May be identified on newborn screening
Absent red blood cell GALT activity
Treatment

Galactose-free diet (eg, soy-based formula)

Question 14

A 6-year-old boy is brought to the office due to progressive difficulty walking and back pain for 2 months. Medical history is also significant for a recent onset of daytime and nighttime urinary incontinence although the patient had been fully toilet trained before age 3. Family history is unremarkable. Vital signs are normal. Examination shows high arches of the feet with fixed flexion of the lower extremity digits. The spine has normal contour. Bilateral lower extremities have decreased strength and 1+ reflexes. Which of the following is the most likely diagnosis in this patient?

A.Muscular dystrophy

B.Spastic diplegia

C.Tethered cord

D.Transverse myelitis

Answer 14

Closed spinal dysraphism

Pathophysiology

Failure of posterior vertebral arch fusion
± Spinal cord anomalies (eg, lipoma, cyst)
Stretch-induced distal spinal cord dysfunction (tethered cord)
Clinical features

May be asymptomatic
Cutaneous, lumbosacral anomalies (eg, hair tuft, mass)
Tethered cord syndrome*:
Neurologic: LMN signs (weakness, hyporeflexia)
Urologic: incontinence/retention; recurrent UTI
Orthopedic: back pain, scoliosis, foot deformities
Management

MRI of the spine
Surgical untethering of cord if symptomatic

Question 15

A 15-year-old boy is brought to the office by his parents due to worsening articulation and gait instability. His parents say that his speech has been increasingly difficult to understand over the last 2 months, but he has had no difficulty with comprehension. The patient has also had progressive gait instability over the last month. He is falling more frequently and had to quit his basketball team. He has no chronic medical problems or allergies. The patient takes no medications and does not use alcohol or illicit drugs. Blood pressure is 120/70 mm Hg and pulse is 80/min. Musculoskeletal examination shows scoliosis. Neurologic examination reveals dysarthria and a wide-based, unstable gait. There are absent deep tendon reflexes of the bilateral lower extremities. MRI of the brain and spinal cord shows marked atrophy of the medulla and dorsal columns of the spinal cord. This patient is at greatest risk of mortality from which of the following conditions?

A.Cardiac dysfunction

B.Diabetic nephropathy

C.Malignancy

D.Respiratory failure

E.Status epilepticus

Answer 15

Friedreich ataxia

Genetics

Autosomal recessive
Loss-of-function, trinucleotide repeat (GAA) in frataxin gene
Clinical features

Neurologic deficits
Cerebellar ataxia
Dysarthria
Loss of vibration and/or position sense
Absent deep tendon reflexes
Hypertrophic cardiomyopathy
Skeletal deformities (eg, scoliosis)
Diabetes mellitus
Prognosis

Mean survival age 30-40
Mortality due to cardiac dysfunction (eg, arrhythmia, congestive heart failure)

Question 16

An 18-month-old boy is brought to the emergency department for evaluation of a productive cough and fever. He has had 8 office and emergency department visits over the past year, all of which required antibiotics for sinusitis and pneumonia. The patient was delivered vaginally without complications. His older brother has had similar recurrent infections. Temperature is 38.9 C (102 F), blood pressure is 90/60 mm Hg, pulse is 120/min, and respirations are 30/min. Pulse oximetry is 99% on room air. Examination of the oropharynx shows mildly enlarged tonsils without erythema or exudate. Auscultation demonstrates rales and rhonchi in both lungs, and the point of maximal impulse is displaced into the right side of the chest. What is the most likely diagnosis in this patient?

A.Common variable immunodeficiency

B.Cystic fibrosis

C.Foreign body

D.Kartagener syndrome

E.Normal childhood infections

F.X-linked agammaglobulinemia

Answer 16

This patient has recurrent sinopulmonary infections with a point of maximal impulse (PMI) on the right. These findings are suggestive of Kartagener syndrome (KS), a subgroup of primary ciliary dyskinesia (PCD) (immotile cilia syndrome). PCD is an autosomal recessive disorder characterized by dysmotile cilia that results from the aberrant production or attachment of ciliary dynein arms. These mutations cause impaired cilial function, poor mucociliary clearance of secretions, and chronic infections.

KS is characterized by a classic triad of situs inversus, recurrent sinusitis, and bronchiectasis. The typical radiographic finding is dextrocardia (apex of the heart in the right chest), which can be detected on physical examination by displaced heart sounds and a PMI to the right (rather than on the left), as in this patient. Although there is no gold standard for diagnosis, KS can be diagnosed with a suggestive phenotype and demonstration of abnormal mucociliary transport.

(Choice A) Common variable immunodeficiency results from low immunoglobulin levels and typically presents in adolescence or adulthood. Affected patients exhibit recurrent sinopulmonary infections but not dextrocardia.

Choice F) X-linked agammaglobulinemia can present with recurrent respiratory tract infections, but patients characteristically have no tonsillar or adenoidal tissue due to lack of mature B cells

Question 17

A 6-year-old boy is brought to the office by his mother for assessment of anxiety. His mother says, “He has started rubbing and picking at his skin. He stayed home with me before starting school and I am concerned this is caused by anxiety.” The patient started kindergarten a few months ago and is struggling to keep up in class. He can copy shapes but is unable to write letters or count to 10. His teacher noted that the patient tends to stay to himself and speaks very little. Medical history is significant for feeding difficulty as an infant, requiring supplemental feeding. The patient was able to sit at age 18 months and to walk at age 3 years. Vital signs are within normal limits. He is currently tracking on the 10th percentile for height and 90th percentile for weight. Physical examination is significant for an overweight child with a narrow forehead, almond-shaped eyes, and red excoriations over the left hand and arm. The patient is noted to have small hands and genitalia. He makes little eye contact and begins to cry when the physician asks him questions. Which of the following is likely to be found on diagnostic testing?

A.Chromosomal trisomy

B.Elevated serum phenylalanine levels

C.Hypothyroidism

D.Increased serum uric acid levels

E.Loss of expression of a uniparental allele

F.MECP2 genetic mutation

Answer 17

Prader-Willi syndrome

Clinical features

Hypotonia
Weak suck/feeding problems in infancy
Hyperphagia/obesity
Short stature
Hypogonadism
Intellectual disability
Dysmorphic facies
Narrow forehead
Almond-shaped eyes
Downturned mouth
Diagnosis

Loss of expression on paternal chromosome 15 (q11-q13)
Complications

Sleep apnea (70%)
Type 2 diabetes mellitus (25%)
Gastric distension/rupture
Death by choking (8%)

Question 18

A 7-month-old boy is brought to the office due to streaks of blood in his stools. The infant was exclusively breastfed until a month ago, when rice cereal and cow’s milk–based formula were introduced into his diet. Previously, stools were soft and yellow and occurred at least once a day. For the past 3 weeks, however, stools have become hard and pellet-like, occurring every 2-3 days. In the past week, the patient’s mother noticed thin streaks of bright red blood on the outside of the stools. The patient has had no change in appetite, vomiting, or fever. Height and weight have been tracking along the 25th percentile since birth. Vital signs are normal. On examination, the patient is in no distress. The abdomen is mildly distended, and there is no pain on palpation. There is firmness on palpation in the left lower quadrant and a small anal fissure at the 6 o’clock position. The remainder of the examination is unremarkable. Which of the following is the most appropriate management of this patient?

A.Add prune puree to diet

B.Obtain a barium enema

C.Obtain an abdominal radiograph

D.Switch to a soy-based formula

E.Switch to an extensively hydrolyzed formula

Answer 18

Infant constipation

Functional

Pathologic causes

Risk factors

Introduction of solid foods
↓ Water intake
↓ Fiber diet
Down syndrome
Abnormal physical findings (eg, displaced anus, tuft at gluteal cleft)
Clinical features

Infrequent defecation
Hard, painful stools
Large-caliber or pellet-like stools
± Anal fissure
Delayed passage of meconium
Fever or vomiting
Ribbon stools
Poor growth
Severe abdominal distension
Management

Add undigestable, osmotically active carbohydrate (eg, prune or apple juice/puree)
Workup for serious organic cause
Hirschsprung disease (barium enema)
Cystic fibrosis (sweat chloride test)
Spinal dysraphism (MRI)

Question 19

A 10-year-old boy is brought to the clinic due to headache, vomiting, and visual disturbances. The patient has had 2 weeks of persistent headache; he was given over-the-counter analgesics but had no relief. He has also had daily episodes of nonbloody, nonbilious emesis. Neurologic examination shows bilateral retraction of the upper eyelids and limitation of upward gaze with a preference for downward gaze. Pupils react sluggishly to light but respond appropriately to accommodation. Strength, sensation, and deep tendon reflexes are normal. Gait is normal. Plantar reflexes are downgoing bilaterally. Which of the following lesions is most likely responsible for this patient’s symptoms?

A.Craniopharyngioma

B.Medulloblastoma

C.Neuroblastoma

D.Pinealoma

E.Retinoblastoma

Answer 19

This patient’s persistent headache and ocular abnormalities are concerning for a pineal gland tumor, or pinealoma. The pineal gland is in the quadrigeminal cistern and is responsible for melatonin production. Pineal gland tumors are rare, and germ cell tumors account for most masses. Children age 1-12 are most commonly affected.

Symptoms of pineal tumors are typically caused by mass effect. Parinaud syndrome (or dorsal midbrain syndrome) results from pressure on the pretectal region of the midbrain near the superior colliculus and the oculomotor nerve (CN III). Classic examination findings include limitation of upward gaze (ie, downward gaze preference) and light-near dissociation (ie, pupils reactive to accommodation but not to light), as seen in this patient. Patients also typically have bilateral eyelid retraction (ie, Collier sign), resulting in visible sclera above the superior corneal limbus.

Pineal gland masses often block cerebrospinal fluid flow in the aqueduct of Sylvius, causing obstructive hydrocephalus. Papilledema, headache, and vomiting can occur due to increased intracranial pressure. Progressive hydrocephalus may also lead to ataxia.

(Choice A) Craniopharyngiomas are suprasellar masses that can compress the optic chiasm, causing visual field deficits. They are not associated with Parinaud syndrome.

Question 20

A 4-month-old boy is brought to the office due to abnormal twisting movements of the limbs and torso. The patient also is not able to push up on his arms when prone. He was born at full term to a 30-year-old woman by forceps-assisted vaginal delivery. The delivery was complicated by cephalohematoma. The patient has not been evaluated since discharge at age 2 days. Vital signs are normal. Weight and length are at the 50th percentile for age. His eyes are crossed, and he does not react to sound. Dystonic extremities are noted on examination. Which of the following is the most likely explanation for this patient’s current condition?

A.Autoimmune injury to basal ganglia

B.Bilirubin-induced neurotoxicity

C.MECP2 gene mutation

D.Physiologic chorea of infancy

E.Trinucleotide repeat expansion on chromosome 4p

Answer 20

Bilirubin-induced neurologic dysfunction

Pathophysiology

Excess levels of free, unconjugated bilirubin cross the blood-brain barrier
Deposition of bilirubin in basal ganglia & brainstem nuclei
Neuronal damage, necrosis & atrophy
Risk factors

Prematurity
Hemolysis (eg, G6PD deficiency)
Birth trauma (eg, cephalohematoma)
Exclusive breastfeeding with excessive weight loss
Acute
encephalopathy

± Reversible (treatment: phototherapy, exchange transfusion)
Clinical findings
Lethargy or inconsolability
Hypotonia (early) or hypertonia (late)
Apnea/respiratory failure, feeding difficulties, seizures
Chronic
encephalopathy

Irreversible
Clinical findings
Developmental delay
Sensorineural hearing loss
Choreoathetoid movements
Upward gaze palsy

Question 21

A 5-year-old boy is brought to the clinic by his parents due to hearing loss. Over the past year, the patient has had increased difficulty hearing normal conversations. He was born at 36 weeks gestation and was small for gestational age but otherwise has had no medical problems. He is at the 50th-75th percentile for height, weight, and head circumference. A tuning fork held over the middle of the forehead sounds louder in the left ear. Tuning fork sounds are better heard with air conduction bilaterally. Which of the following is the most likely etiology of this patient’s hearing loss?

A.Cholesteatoma

B.Chronic otitis media

C.Congenital infection

D.Foreign body

E.Noise exposure

F.Otosclerosis

Answer 21

Interpretation of Rinne & Weber tests

Rinne result

Weber result

Normal

AC > BC in both ears

Midline

Conductive
hearing loss

BC > AC in affected ear,
AC > BC in unaffected ear

Lateralizes to affected ear

Sensorineural
hearing loss

AC > BC in both ears

Lateralizes to unaffected ear,
away from affected ear

Mixed
hearing loss

BC > AC in affected ear,
AC > BC in unaffected ear

Lateralizes to unaffected ear,
away from affected ear

Question 22

A 1-year-old boy is brought to the clinic to establish care after his family’s recent move to the area. The patient was born at full term and has been growing and developing normally. Each day, he eats meat and pasta and drinks 300 mL (10 oz) of whole milk; however, he does not eat fruit and vegetables. The patient takes no daily medications or vitamins. Weight and height are at the 50th percentile. Conjunctivae and mucous membranes are pale. Cardiac examination reveals no murmurs. Pulmonary examination is normal. The abdomen is soft, and no hepatosplenomegaly is noted. Complete blood count results are as follows:

Hemoglobin 10 g/dL (normal: 10.5-13.5)
Red blood cells 6.1 million/mm3 (normal: 3.7-6)
Mean corpuscular volume 60 µm3 (normal: 70-86)
Red cell distribution width 13% (normal: 11.5%-14.5%)
Reticulocytes 4% (normal: 0.5%-1.5%)
Which of the following is the most likely cause of this patient’s anemia?

A.Anemia of chronic disease

B.Folate deficiency

C.Hereditary spherocytosis

D.Iron deficiency

E.Thalassemia minor

Answer 22

The most common causes of microcytic anemia in children are iron deficiency and thalassemia. Thalassemia is caused by impaired production of alpha- or beta-globin chains of hemoglobin. Clinical manifestations range from minor to severe, depending on the number of globin chains affected. Alpha- and beta-thalassemia minor (also known as thalassemia trait) are often asymptomatic and found incidentally on laboratory testing. Patients with thalassemia minor are often diagnosed by universal screening for anemia around age 1.

Both types of thalassemia minor are characterized by abnormally small red blood cells (RBCs), reflected by a low mean corpuscular volume (MCV). A normal red cell distribution width (RDW) and normal-to-elevated total RBCs typically result in a Mentzer index (MCV/RBC) <13. Reticulocyte count may be slightly elevated due to a compensatory bone marrow response to anemia.

Iron studies are typically performed to exclude iron deficiency anemia. Increased RBC turnover in thalassemia minor may result in slightly increased serum iron and ferritin levels. In addition, a peripheral smear of thalassemia shows target and teardrop cells.

(Choice A) Anemia of chronic disease is typically normocytic and normochromic but can be mildly microcytic; reticulocyte count is low due to decreased erythrocyte production. Anemia of chronic disease is unlikely in this child with no chronic medical problems.

(Choice B) Folate deficiency presents as a macrocytic anemia (MCV >100 µm3) and occurs in individuals with poor dietary intake of vegetables or with increased requirements due to chronic hemolysis.

(Choice C) Hereditary spherocytosis is caused by RBC membrane instability and typically presents with anemia, jaundice, and splenomegaly. Laboratory results demonstrate reticulocytosis, an elevated mean corpuscular hemoglobin concentration, a normal or slightly low MCV, a normal-to-elevated RDW, and spherocytosis.

(Choice D) Iron deficiency anemia is the most common cause of microcytic anemia in children and is often caused by excessive cow’s milk intake (>700 mL [24 oz] daily). Distinguishing laboratory findings include an increased RDW, a Mentzer index >13 (due to a decline in RBC count), and a low reticulocyte count.

Question 23

A 5-day-old girl is brought to the emergency department due to white vaginal discharge with streaks of blood since yesterday. The patient does not appear to be in pain and has been voiding and stooling adequately. She is exclusively breastfed every 2-3 hours. The mother mentions that she was treated “with a shot and a pill” for a sexually transmitted infection early in her pregnancy and subsequently tested negative. The patient was born via forceps-assisted vaginal delivery at 38 weeks gestation. She lives at home with her parents and 9-year-old sister. Temperature is 36.7 C (98 F). On physical examination, a white, mucoid vaginal discharge with streaks of blood is noted. The remainder of the examination is unremarkable. Which of the following is the most likely cause of this patient’s vaginal discharge?

A.Candidal vaginitis

B.Chlamydia trachomatis infection

C.Group A streptococcal vaginal infection
D.Maternal hormone withdrawal

E.Vaginal foreign body

Answer 23

Neonatal withdrawal bleeding

Physiology

In utero: maternal estrogen stimulates fetal endometrial proliferation
After delivery: withdrawal of maternal hormones → endometrial sloughing in neonate
Clinical features

Light vaginal bleeding in first 2 weeks of life
± Additional signs of maternal estrogen exposure:
Physiologic leukorrhea
Labial swelling
Breast hypertrophy ± galactorrhea
Diagnosis & management

Clinical diagnosis
Reassurance for parents
Resolves on its own within days

Question 24

A 16-year-old boy is brought to the clinic for evaluation of headaches. For the last month, he has had daily, throbbing pain in the frontal region that is worse in the morning and occasionally associated with nausea and vomiting. Acetaminophen provides some relief. The patient also had several brief episodes of blurriness in his left eye during football practice last week. In addition to acetaminophen, he takes oral isotretinoin for severe acne. Temperature is 36.7 C (98.1 F), blood pressure is 130/80 mm Hg, pulse is 70/min, and respirations are 15/min. The patient is sitting up and cooperative with the examination. The pupils are equal and reactive to light. Eye examination shows bilateral optic disc edema and decreased visual acuity. The visual fields are full. There is no neck stiffness. Motor examination reveals 5/5 strength, 2+ deep tendon reflexes, and a normal plantar response. Sensory examination is unremarkable. Which of the following is the most likely explanation of this patient’s symptoms?

A.Cluster headaches

B.Medication effect

C.Optic chiasm glioma

D.Optic neuritis

E.Viral encephalitis

Answer 24

Idiopathic intracranial hypertension

Risk factors

Women of childbearing age
Recent weight gain/obesity
Medications (eg, retinoids/vitamin A, tetracyclines, growth hormone)
Pathophysiology

Impaired CSF resorption & intracranial venous hypertension
Clinical
features

Headache/nausea/vomiting
Visual changes (transient obscurations; vision loss; diplopia due to abducens nerve [CN VI] palsy)
Pulsatile tinnitus
Retrobulbar pain/neck pain/back pain
Diagnosis

Papilledema & enlarged blind spots
MRI to rule out mass lesions/hydrocephalus
MR venography to rule out venous thrombosis
Lumbar puncture: elevated opening pressure
Treatment

Weight loss, including bariatric surgery
Carbonic anhydrase inhibitor (acetazolamide, topiramate)

Question 25

Hyper-IgE syndrome

Answer 25

Pathogenesis

Autosomal dominant
Defective JAK-STAT signaling → impaired Th17
↓ Neutrophil proliferation/chemotaxis
Clinical
features

Severe, chronic eczema
Noninflammatory (ie, cold) abscesses (eg, Staphylococcus, Candida)
Recurrent sinopulmonary infections
Dysmorphic facies (eg, broad nose, prominent forehead)
Retained primary teeth
Laboratory
findings

↑ IgE
Eosinophilia
Normal leukocyte count with ↓ Th17
Management

Supportive skin care
Antibiotic prophylaxis & treatment

Question 26

Key features of congenital infections*

Answer 26

Toxoplasmosis

Chorioretinitis
Hydrocephalus
Diffuse intracranial calcifications
Syphilis

Rhinorrhea
Skeletal anomalies
Desquamating rash (palms/soles)
Rubella

Cataracts
Heart defects (eg, PDA)
Sensorineural hearing loss
Cytomegalovirus

Periventricular calcifications
Microcephaly
Sensorineural hearing loss
Herpes simplex virus

Vesicular/ulcerative rash