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4. Pediatrics MCQs

Practice Set 325 of 334

This practice set contains high-yield board review questions covering key concepts in 4. Pediatrics. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 6481

Topic: 4. Pediatrics

A 4-year-old boy presents with disproportionate short-trunk short stature, a flat midface, and coxa vara. His hands and feet are of normal size. Radiographs reveal delayed epiphyseal ossification and marked platyspondyly. Which of the following genes is most likely mutated in this patient?

. COMP
. COL2A1
. FGFR3
. TRAPPC2
. EXT1

Correct Answer & Explanation

. COL2A1

Explanation

Spondyloepiphyseal Dysplasia Congenita (SEDC) is caused by autosomal dominant mutations in the COL2A1 gene. It is characterized by short-trunk dwarfism, coxa vara, and platyspondyly, while the hands and feet typically remain normal.

Question 6482

Topic: 4. Pediatrics

A 3-year-old child presents with severe joint hyperlaxity, a waddling gait, and disproportionate short stature. Radiographs show delayed epiphyseal ossification and irregular, fragmented metaphyses. Which craniofacial feature distinguishes this patient's most likely diagnosis from achondroplasia?

. Frontal bossing
. Midface hypoplasia
. Normal craniofacial features
. Cleft palate
. Craniosynostosis

Correct Answer & Explanation

. Normal craniofacial features

Explanation

This presentation is highly characteristic of pseudoachondroplasia (COMP gene mutation). Unlike achondroplasia, patients with pseudoachondroplasia have completely normal craniofacial features and head circumferences.

Question 6483

Topic: 4. Pediatrics
An infant is born with asymmetric limb shortening, cataracts, and ichthyosis. Skeletal survey reveals punctate calcifications of the epiphyses. The mother had no complications or medication usage during pregnancy. Which of the following is the most likely mode of inheritance for this patient's condition?
. Autosomal recessive
. X-linked dominant
. Maternal imprinting
. Autosomal dominant
. Mitochondrial

Correct Answer & Explanation

. X-linked dominant

Explanation

Conradi-Hünermann syndrome is the X-linked dominant form of chondrodysplasia punctata, caused by mutations in the EBP gene. It predominantly affects females and is classically associated with asymmetric limb shortening and ichthyosis.

Question 6484

Topic: 4. Pediatrics

A 3-year-old child presents with severe joint stiffness and prominent, enlarged joints. A skeletal survey reveals dumbbell-shaped femora and distinct coronal clefts in the vertebral bodies. Which of the following is the most likely diagnosis?

. Multiple Epiphyseal Dysplasia
. Kniest Dysplasia
. Chondrodysplasia Punctata
. Achondroplasia
. Osteogenesis Imperfecta

Correct Answer & Explanation

. Kniest Dysplasia

Explanation

Kniest dysplasia is a severe type II collagenopathy (COL2A1 mutation). It is classically identified by clinical joint enlargement and radiographic findings of dumbbell-shaped long bones and coronal vertebral clefts.

Question 6485

Topic: 4. Pediatrics

An infant is evaluated for profound developmental delay, cataracts, and severe rhizomelic shortening of the limbs. Radiographs show punctate epiphyseal calcifications. Genetic testing reveals a mutation in the PEX7 gene. Which of the following metabolic processes is fundamentally impaired?

. Peroxisome biogenesis
. Lysosomal sphingolipid degradation
. Mitochondrial oxidative phosphorylation
. Endoplasmic reticulum protein folding
. Cholesterol synthesis

Correct Answer & Explanation

. Peroxisome biogenesis

Explanation

Rhizomelic chondrodysplasia punctata is an autosomal recessive disorder caused by mutations in PEX7. This leads to defective peroxisome biogenesis, causing severe neurodevelopmental deficits and early mortality.

Question 6486

Topic: 4. Pediatrics

A 3-year-old girl is evaluated for a waddling gait and short stature. Clinical examination reveals completely normal facial features and head circumference, but marked shortening of the limbs. Radiographs show fragmented epiphyses, widened metaphyses, and platyspondyly with anterior tongue-like projections. What is the most likely genetic etiology?

. FGFR3 mutation
. COMP mutation
. COL2A1 mutation
. TRAPPC2 mutation
. SOX9 mutation

Correct Answer & Explanation

. COMP mutation

Explanation

Pseudoachondroplasia presents with severely affected epiphyses and metaphyses but normal craniofacial features, distinguishing it from classic achondroplasia. It is caused by mutations in the COMP (Cartilage Oligomeric Matrix Protein) gene.

Question 6487

Topic: 4. Pediatrics

A 2-year-old boy presents with short trunk dwarfism, prominent stiff joints, a repaired cleft palate, and severe myopia. Radiographs reveal coronal clefts of the vertebral bodies, broad metaphyses, and prominent 'dumbbell-shaped' femora. Which of the following genes is most likely mutated?

. FGFR3
. COMP
. COL2A1
. SLC26A2
. EXT1

Correct Answer & Explanation

. COL2A1

Explanation

Kniest dysplasia is a type II collagenopathy caused by mutations in the COL2A1 gene. It is clinically characterized by severe myopia, cleft palate, short trunk dwarfism, and classic radiographic findings of dumbbell-shaped femora and coronal clefts in the vertebrae.

Question 6488

Topic: Pediatric Hip
A 2-year-old boy is brought in for a mild waddling gait. Radiographs show delayed, irregular ossification of both capital femoral epiphyses without metaphyseal cysts, subchondral fractures, or acetabular abnormalities. The spine is unaffected. By age 5, follow-up radiographs show near-complete resolution. What is the most likely diagnosis?
. Legg-Calvé-Perthes disease
. Multiple Epiphyseal Dysplasia
. Spondyloepiphyseal Dysplasia Congenita
. Hypothyroidism
. Meyer dysplasia

Correct Answer & Explanation

. Meyer dysplasia

Explanation

Meyer dysplasia is a self-limiting condition characterized by delayed and irregular ossification of the capital femoral epiphysis, typically presenting around age 2. Unlike Legg-Calvé-Perthes disease, it lacks metaphyseal cysts or subchondral fractures and normalizes without surgical intervention.

Question 6489

Topic: 4. Pediatrics

A 6-year-old girl presents with short stature, a waddling gait, and joint hyperlaxity. Her facial features and head circumference are completely normal. Radiographs reveal irregular epiphyses, widened metaphyses, and spatulate ribs. A mutation in the gene encoding which of the following proteins is most likely responsible?

. Type II collagen
. Cartilage oligomeric matrix protein (COMP)
. Fibroblast growth factor receptor 3 (FGFR3)
. Transcription factor Runx2
. Type X collagen

Correct Answer & Explanation

. Cartilage oligomeric matrix protein (COMP)

Explanation

The clinical picture describes pseudoachondroplasia, which uniquely spares the craniofacies unlike achondroplasia. It is caused by mutations in the COMP gene, leading to accumulation of misfolded proteins in the rough endoplasmic reticulum of chondrocytes.

Question 6490

Topic: Pediatric Hip

A 9-year-old girl presents with bilateral hip stiffness and a waddling gait. Radiographs show delayed ossification and flattening of the capital femoral epiphyses. Which of the following radiographic features best distinguishes Multiple Epiphyseal Dysplasia (MED) from bilateral Legg-Calve-Perthes disease?

. Unilateral involvement
. Presence of metaphyseal cysts
. Symmetrical bilateral involvement without varying stages of healing
. Presence of a subchondral fracture (crescent sign)
. Development of coxa magna

Correct Answer & Explanation

. Symmetrical bilateral involvement without varying stages of healing

Explanation

MED typically presents with highly symmetrical bilateral epiphyseal changes. In contrast, bilateral Legg-Calve-Perthes disease is almost always asynchronous, presenting in varying stages of necrosis and healing between the two hips.

Question 6491

Topic: 4. Pediatrics

A newborn is evaluated for asymmetrical shortening of the limbs, severe ichthyosis, and congenital cataracts. Radiographs demonstrate stippled calcifications within the epiphyses of the long bones and the spine. What is the inheritance pattern of the Conradi-Hunermann type of this disorder?

. Autosomal dominant
. Autosomal recessive
. X-linked dominant
. X-linked recessive
. Mitochondrial

Correct Answer & Explanation

. X-linked dominant

Explanation

Conradi-Hunermann syndrome is the X-linked dominant form of Chondrodysplasia Punctata, caused by mutations in the EBP gene. It is typically lethal in males and presents in females with asymmetric limb shortening, stippled epiphyses, and ichthyosis.

Question 6492

Topic: 4. Pediatrics

A 12-year-old boy presents with progressive hip pain and back stiffness. Physical exam reveals a disproportionately short trunk. Radiographs reveal platyspondyly with a characteristic hump-shaped buildup of bone on the central and posterior portions of the vertebral endplates. This condition is most commonly linked to a mutation in which of the following?

. TRAPPC2 gene
. COL2A1 gene
. COMP gene
. FGFR3 gene
. SLC26A2 gene

Correct Answer & Explanation

. TRAPPC2 gene

Explanation

The patient has Spondyloepiphyseal Dysplasia (SED) tarda, characterized by onset in late childhood and hump-shaped vertebral endplates. It is inherited in an X-linked recessive pattern due to mutations in the TRAPPC2 (sedlin) gene.

Question 6493

Topic: 4. Pediatrics

A newborn presents with short-limb dwarfism, characteristic hitchhiker thumbs, bilateral rigid clubfeet, and cystic swelling of the external ears (cauliflower ears). Which of the following gene mutations is most directly responsible for this epiphyseal dysplasia variant?

. COL2A1
. FGFR3
. SLC26A2
. COMP
. MATN3

Correct Answer & Explanation

. SLC26A2

Explanation

The clinical presentation is classic for Diastrophic Dysplasia. It is caused by an autosomal recessive mutation in the SLC26A2 gene, which encodes a sulfate transporter crucial for cartilage matrix formation.

Question 6494

Topic: 4. Pediatrics

A 5-year-old boy presents with mild epiphyseal changes on radiographs, a cleft palate, micrognathia, and severe myopia. He has a history of early-onset hearing loss and hypermobile joints. Which of the following conditions is the most likely diagnosis?

. Multiple Epiphyseal Dysplasia
. Pseudoachondroplasia
. Stickler syndrome
. Kniest dysplasia
. Achondroplasia

Correct Answer & Explanation

. Stickler syndrome

Explanation

Stickler syndrome is a collagenopathy (often COL2A1) presenting with Pierre Robin sequence (cleft palate, micrognathia), epiphyseal dysplasia, eye abnormalities (myopia), and sensorineural hearing loss.

Question 6495

Topic: 4. Pediatrics

A 4-year-old boy with disproportionate short-trunk dwarfism presents for orthopedic evaluation. He has a history of cleft palate and severe myopia. Radiographs reveal delayed ossification of the capital femoral epiphyses, severe coxa vara, and flattened, pear-shaped vertebral bodies. Prior to any surgical intervention requiring general anesthesia, flexion-extension radiographs of the cervical spine must be obtained to rule out atlantoaxial instability. This patient's condition is caused by a mutation affecting which of the following proteins?

. Cartilage oligomeric matrix protein (COMP)
. Type II collagen (COL2A1)
. Fibroblast growth factor receptor 3 (FGFR3)
. Diastrophic dysplasia sulfate transporter (SLC26A2)
. Sedlin (TRAPPC2)

Correct Answer & Explanation

. Type II collagen (COL2A1)

Explanation

Spondyloepiphyseal dysplasia congenita (SEDC) is an autosomal dominant disorder caused by a mutation in the COL2A1 gene, which encodes Type II collagen. Classic features include short-trunk dwarfism, myopia, cleft palate, coxa vara, and a high risk of atlantoaxial instability, making cervical spine clearance mandatory before anesthesia.

Question 6496

Topic: Pediatric Hip

A 13-year-old obese male presents with a 3-week history of left knee pain and a noticeable limp. He denies any recent trauma. On examination, his left leg is externally rotated, and he has obligatory external rotation when the hip is flexed to 90 degrees. Radiographs confirm a posterior and inferior displacement of the proximal femoral epiphysis. Which of the following is the most appropriate definitive management to prevent further displacement while minimizing the risk of avascular necrosis?

. Closed reduction and spica casting
. Open reduction and internal fixation with multiple pins
. In situ fixation with a single cannulated screw
. Proximal femoral osteotomy
. Observation and non-weight bearing with crutches

Correct Answer & Explanation

. In situ fixation with a single cannulated screw

Explanation

Correct Answer: CThe patient has a stable Slipped Capital Femoral Epiphysis (SCFE), which frequently presents with referred knee pain and obligatory external rotation during hip flexion. The standard of care for a stable SCFE is in situ fixation, typically with a single central cannulated screw, to prevent further slippage. Closed reduction is strictly contraindicated as it significantly increases the risk of avascular necrosis (AVN) of the femoral head by disrupting the already tenuous retinacular blood supply.

Question 6497

Topic: Pediatric Lower Extremity

A 2-week-old male infant is brought to the clinic for evaluation of bilateral foot deformities present since birth. Examination reveals equinus of the ankle, varus of the hindfoot, adductus of the forefoot, and cavus of the midfoot. The physician decides to initiate the Ponseti method of serial casting. Which of the following describes the correct sequence of deformity correction in this method?

. Equinus, Varus, Adductus, Cavus
. Cavus, Adductus, Varus, Equinus
. Adductus, Cavus, Varus, Equinus
. Varus, Cavus, Adductus, Equinus
. Cavus, Varus, Adductus, Equinus

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

Correct Answer: BThe Ponseti method is the gold standard for treating idiopathic clubfoot (talipes equinovarus). The deformities must be corrected in a specific sequence, remembered by the acronym CAVE: Cavus (corrected first by elevating the first ray to align the forefoot with the hindfoot), Adductus, Varus, and finally Equinus. The equinus is corrected last, and often requires a percutaneous Achilles tenotomy to achieve adequate dorsiflexion.

Question 6498

Topic: 4. Pediatrics

A 13-year-old obese male presents with a 3-week history of vague left knee and thigh pain. He walks with an antalgic gait. On examination, as the left hip is passively flexed, it obligatorily externally rotates. Internal rotation is limited to 5 degrees. Radiographs show a widening of the proximal femoral physis. What is the most appropriate definitive management for this patient's condition?

. Spica casting
. Closed reduction and internal fixation
. In situ single screw fixation
. Open reduction and internal fixation
. Protected weight-bearing and observation

Correct Answer & Explanation

. In situ single screw fixation

Explanation

Correct Answer: CPathophysiology:Slipped Capital Femoral Epiphysis (SCFE) is an adolescent hip disorder characterized by the displacement of the proximal femoral epiphysis on the metaphysis through the hypertrophic zone of the physis. It is most commonly seen in obese adolescents undergoing rapid growth spurts.Clinical Presentation:Patients typically present with groin, thigh, or knee pain (referred pain via the obturator nerve) and an antalgic gait. A classic physical exam finding is obligatory external rotation of the hip during passive flexion, along with limited internal rotation.Management:The definitive and immediate management for a stable SCFE is in situ single screw fixation to prevent further slippage and promote premature closure of the physis. Open reduction is generally reserved for unstable or severe slips due to the high risk of avascular necrosis (AVN). Spica casting is obsolete due to high rates of chondrolysis.

Question 6499

Topic: 4. Pediatrics

A newborn male is evaluated in the nursery and found to have bilateral rigid foot deformities characterized by equinus, varus, adductus, and cavus. The pediatrician diagnoses idiopathic talipes equinovarus. What is the gold standard initial treatment for this condition?

. Immediate posteromedial release surgery
. Serial casting using the Ponseti method
. Application of a Denis Browne splint
. Physical therapy and stretching exercises
. Observation until the child begins to walk

Correct Answer & Explanation

. Serial casting using the Ponseti method

Explanation

Correct Answer: BPathoanatomy:Idiopathic clubfoot (talipes equinovarus) is a complex congenital deformity involving four main components: Cavus (midfoot), Adductus (forefoot), Varus (hindfoot), and Equinus (hindfoot) - remembered by the acronym CAVE.Treatment:The Ponseti method is the universally accepted gold standard for initial treatment. It involves a specific sequence of serial manipulations and long-leg casting to gradually correct the deformities in the order of C-A-V-E. The cavus is corrected first by elevating the first ray. The equinus is corrected last, often requiring a percutaneous Achilles tenotomy. Extensive surgical releases are now rarely performed due to long-term stiffness and pain.

Question 6500

Topic: 4. Pediatrics
A 9-year-old boy falls off his skateboard and injures his right wrist. Radiographs reveal a fracture line that extends transversely through the physis of the distal radius and exits obliquely through the metaphysis, sparing the epiphysis. According to the Salter-Harris classification, what type of fracture is this?
. Type I
. Type II
. Type III
. Type IV
. Type V

Correct Answer & Explanation

. Type II

Explanation

The Salter-Harris (SH) system categorizes pediatric physeal fractures: Type I: Slipped (fracture straight across the physis). Type II: Above (fracture through the physis exiting through the metaphysis). Type III: Lower (fracture through the physis exiting through the epiphysis). Type IV: Through or Two (fracture through the metaphysis, physis, and epiphysis). Type V: ERasure of growth plate (crush injury to the physis). SH Type II is the most common type of physeal fracture.

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