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4. Pediatrics MCQs

Practice Set 324 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 6461

Topic: 4. Pediatrics

A 5-year-old boy is evaluated for short stature and a waddling gait. Radiographs demonstrate flattened capital femoral epiphyses, coxa vara, and platyspondyly with anterior wedging of the vertebral bodies. What is the most likely diagnosis?

. Multiple Epiphyseal Dysplasia
. Spondyloepiphyseal Dysplasia congenita
. Achondroplasia
. Pseudoachondroplasia

Correct Answer & Explanation

. Spondyloepiphyseal Dysplasia congenita

Explanation

Correct Answer: Spondyloepiphyseal Dysplasia congenitaSpondyloepiphyseal Dysplasia (SED) congenita involves both the epiphyses and the spine. The presence of platyspondyly (flattened vertebral bodies) and anterior wedging is the key differentiator from Multiple Epiphyseal Dysplasia (MED), which typically spares the spine. SED congenita is caused by a defect in type II collagen (COL2A1).

Question 6462

Topic: Pediatric Hip

A 2-year-old boy undergoes a pelvic radiograph following a minor fall. He is completely asymptomatic. The radiograph incidentally reveals delayed and irregular ossification of bilateral capital femoral epiphyses. There is no involvement of other joints. The condition is expected to resolve spontaneously. What is the diagnosis?

. Multiple Epiphyseal Dysplasia
. Legg-Calve-Perthes disease
. Meyer dysplasia
. Hypothyroidism

Correct Answer & Explanation

. Meyer dysplasia

Explanation

Correct Answer: Meyer dysplasiaMeyer dysplasia (dysplasia epiphysealis capitis femoris) is a localized dysplasia of the capital femoral epiphysis characterized by delayed, irregular ossification. It is typically asymptomatic, discovered incidentally in toddlers (usually around age 2), and resolves spontaneously without treatment. It must be differentiated from Perthes disease, which presents later (age 4-8) with pain and necrosis.

Question 6463

Topic: 4. Pediatrics
A newborn presents with short proximal limbs, cataracts, and ichthyosis. Skeletal survey radiographs reveal calcific stippling of the epiphyses around the hips, knees, and ankles. What is the most likely diagnosis?
. Chondrodysplasia punctata
. Osteogenesis imperfecta
. Cleidocranial dysplasia
. Diastrophic dysplasia

Correct Answer & Explanation

. Chondrodysplasia punctata

Explanation

Chondrodysplasia punctata is a group of disorders characterized by 'stippled epiphyses' (punctate calcifications in the infantile cartilaginous epiphyses). It is often associated with extra-skeletal manifestations such as cataracts and skin changes (ichthyosis), particularly in the Conradi-Hünermann (X-linked dominant) type.

Question 6464

Topic: 4. Pediatrics

Pseudoachondroplasia is a skeletal dysplasia that presents with short-limb dwarfism and joint laxity, but normal facial features. It shares its primary genetic mutation with which of the following skeletal dysplasias?

. Achondroplasia
. Multiple Epiphyseal Dysplasia
. Spondyloepiphyseal Dysplasia
. Diastrophic Dysplasia

Correct Answer & Explanation

. Multiple Epiphyseal Dysplasia

Explanation

Correct Answer: Multiple Epiphyseal DysplasiaBoth Pseudoachondroplasia and the most common autosomal dominant form of Multiple Epiphyseal Dysplasia (MED) are caused by mutations in the COMP (Cartilage Oligomeric Matrix Protein) gene. They are considered part of the same phenotypic spectrum of COMP-opathies, with Pseudoachondroplasia being the more severe clinical manifestation.

Question 6465

Topic: 4. Pediatrics

Which of the following genes is most commonly mutated in the autosomal dominant form of Multiple Epiphyseal Dysplasia (MED), leading to the accumulation of abnormal protein in the rough endoplasmic reticulum of chondrocytes?

. COL2A1
. COMP
. FGFR3
. SLC26A2
. TRAPPC2

Correct Answer & Explanation

. COMP

Explanation

Correct Answer: B (COMP)Mutations in the Cartilage Oligomeric Matrix Protein (COMP) gene on chromosome 19 are the most common cause of autosomal dominant Multiple Epiphyseal Dysplasia (MED) and Pseudoachondroplasia. The mutation causes the abnormal COMP protein to accumulate in the rough endoplasmic reticulum of chondrocytes, leading to premature chondrocyte death and disorganized endochondral ossification. COL2A1 is associated with Spondyloepiphyseal Dysplasia Congenita (SEDC). FGFR3 is associated with Achondroplasia. SLC26A2 causes the autosomal recessive form of MED. TRAPPC2 is associated with X-linked Spondyloepiphyseal Dysplasia Tarda.

Question 6466

Topic: 4. Pediatrics

A 12-year-old girl with mild short stature presents with bilateral knee pain. Lateral radiographs of the knee reveal a 'double-layered' appearance of the patella. Which of the following conditions is most strongly associated with this radiographic finding?

. Spondyloepiphyseal dysplasia congenita
. Multiple epiphyseal dysplasia
. Chondrodysplasia punctata
. Pseudoachondroplasia
. Achondroplasia

Correct Answer & Explanation

. Multiple epiphyseal dysplasia

Explanation

Correct Answer: B (Multiple epiphyseal dysplasia)A double-layered patella (due to delayed or irregular ossification of the patellar epiphysis) is a classic, pathognomonic radiographic sign of Multiple Epiphyseal Dysplasia (MED), particularly the type associated with SLC26A2 (recessive) or COMP mutations. It is best visualized on a lateral radiograph of the knee.

Question 6467

Topic: Pediatric Hip
A 2-year-old boy is incidentally found to have delayed and irregular ossification of bilateral capital femoral epiphyses on a pelvic radiograph taken for a suspected hernia. He has no limp, normal range of motion, and no pain. What is the most appropriate management?
. Bilateral proximal femoral varus derotation osteotomies
. Petrie cast application
. Observation and reassurance
. Core decompression of the femoral heads
. Genetic testing for COL2A1 mutation

Correct Answer & Explanation

. Observation and reassurance

Explanation

Meyer dysplasia (dysplasia epiphysealis capitis femoris) is a localized dysplasia of the femoral head characterized by delayed, irregular ossification. It typically presents in children around 2 years of age, is often bilateral, and is asymptomatic. It resolves spontaneously without intervention by age 5-6. It is crucial to differentiate this from Legg-Calvé-Perthes disease, which presents later (4-8 years) with pain, limp, and requires closer monitoring or intervention.

Question 6468

Topic: 4. Pediatrics

A 4-year-old child presents with disproportionate short stature, a waddling gait, and joint laxity. Radiographs show delayed epiphyseal ossification and irregular, flared metaphyses. The parents note the child's length was normal at birth but growth velocity decreased significantly after age 2. The child has normal facial features and head circumference. What is the most likely diagnosis?

. Achondroplasia
. Hypochondroplasia
. Pseudoachondroplasia
. Spondyloepiphyseal dysplasia congenita
. Diastrophic dysplasia

Correct Answer & Explanation

. Pseudoachondroplasia

Explanation

Correct Answer: C (Pseudoachondroplasia)Pseudoachondroplasia is caused by a COMP mutation. Unlike achondroplasia, patients with pseudoachondroplasia have normal birth length, normal craniofacial features (no frontal bossing or midface hypoplasia), and normal intelligence. Growth deceleration becomes apparent around 2-3 years of age. Radiographs show both epiphyseal and metaphyseal involvement, distinguishing it from pure epiphyseal dysplasias.

Question 6469

Topic: Pediatric Hip

A 7-year-old boy with a known COL2A1 mutation presents with a short trunk, barrel chest, and severe coxa vara. Given his underlying diagnosis of Spondyloepiphyseal Dysplasia Congenita, he should be routinely screened by an ophthalmologist to prevent which of the following complications?

. Glaucoma
. Cataracts
. Retinal detachment
. Optic nerve hypoplasia
. Macular degeneration

Correct Answer & Explanation

. Retinal detachment

Explanation

Correct Answer: C (Retinal detachment)Spondyloepiphyseal Dysplasia Congenita (SEDC) is a type II collagenopathy caused by mutations in the COL2A1 gene. Type II collagen is a major structural component of the vitreous humor of the eye. Patients are highly susceptible to high myopia and retinal detachment, necessitating regular ophthalmologic screening to prevent blindness.

Question 6470

Topic: Pediatric Hip
A 3-year-old boy is incidentally found to have delayed and irregular ossification of bilateral capital femoral epiphyses on a pelvic radiograph taken for a suspected urinary tract infection. He has no limp and no hip pain. Which of the following statements best differentiates this condition from Legg-Calvé-Perthes disease?
. This condition typically presents with severe, unrelenting night pain.
. This condition requires urgent surgical containment to prevent joint destruction.
. This condition shows a fragmented appearance that resolves spontaneously without epiphyseal collapse.
. This condition is inherited in an autosomal dominant pattern.
. This condition primarily affects children older than 8 years.

Correct Answer & Explanation

. This condition shows a fragmented appearance that resolves spontaneously without epiphyseal collapse.

Explanation

The clinical scenario describes Meyer dysplasia, a benign, often asymptomatic condition characterized by delayed and irregular ossification of the capital femoral epiphysis. It typically presents in children aged 2 to 3 years and is frequently bilateral. Unlike Legg-Calvé-Perthes disease, Meyer dysplasia does not progress to epiphyseal collapse or severe deformity, and it resolves spontaneously without the need for surgical containment or bracing.

Question 6471

Topic: 4. Pediatrics

A 7-year-old girl with Dysplasia Epiphysealis Hemimelica (Trevor disease) of the distal medial femur is undergoing evaluation for surgical excision due to progressive angular deformity and joint mechanical symptoms. Which of the following is the most significant complication associated with the surgical excision of these lesions?

. High rate of malignant transformation to chondrosarcoma postoperatively
. Massive intraoperative hemorrhage due to high vascularity
. Premature physeal closure leading to growth arrest and worsening angular deformity
. Development of a chronic, non-healing synovial fistula
. Systemic dissemination of the cartilaginous tissue

Correct Answer & Explanation

. Premature physeal closure leading to growth arrest and worsening angular deformity

Explanation

Correct Answer: Premature physeal closure leading to growth arrest and worsening angular deformitySurgical excision of the epiphyseal overgrowth in Trevor disease is technically challenging because the mass arises directly from the epiphysis and is intimately associated with the physis and articular cartilage. The most significant complication of excision is iatrogenic damage to the physis, which can lead to premature physeal closure, subsequent growth arrest, and worsening of the angular deformity.

Question 6472

Topic: 4. Pediatrics

A 4-year-old child with Spondyloepiphyseal Dysplasia Congenita (SEDC) is being evaluated in a multidisciplinary clinic. Because SEDC is a type II collagenopathy, which of the following extraskeletal manifestations requires rigorous routine screening in this patient?

. Sensorineural hearing loss
. Retinal detachment
. Hepatic fibrosis
. Renal failure
. Mitral valve prolapse

Correct Answer & Explanation

. Retinal detachment

Explanation

Correct Answer: Retinal detachmentSpondyloepiphyseal Dysplasia Congenita (SEDC) is caused by mutations in the COL2A1 gene, which encodes type II collagen. Type II collagen is a major structural component of articular cartilage, the nucleus pulposus, and the vitreous humor of the eye. Consequently, patients with SEDC are at a very high risk for severe myopia and retinal detachment. Routine, rigorous ophthalmologic screening is essential to prevent blindness.

Question 6473

Topic: 4. Pediatrics

Which of the following genetic mutations is responsible for the autosomal recessive form of Chondrodysplasia Punctata (Rhizomelic type), which is characterized by severe proximal limb shortening, profound intellectual disability, and early lethality?

. PEX7 gene mutation affecting peroxisomal biogenesis
. FGFR3 gene mutation affecting endochondral ossification
. COL1A1 gene mutation affecting type I collagen synthesis
. COMP gene mutation affecting cartilage oligomeric matrix protein
. SOX9 gene mutation affecting chondrocyte differentiation

Correct Answer & Explanation

. PEX7 gene mutation affecting peroxisomal biogenesis

Explanation

Correct Answer: PEX7 gene mutation affecting peroxisomal biogenesisRhizomelic Chondrodysplasia Punctata (RCDP) is an autosomal recessive disorder characterized by severe rhizomelic shortening, stippled epiphyses, cataracts, and severe intellectual disability. It is a peroxisomal biogenesis disorder, most commonly caused by mutations in the PEX7 gene, which leads to a defect in the plasmalogen biosynthesis pathway. FGFR3 is associated with achondroplasia. COL1A1 is associated with osteogenesis imperfecta. COMP is associated with MED and pseudoachondroplasia. SOX9 is associated with campomelic dysplasia.

Question 6474

Topic: 4. Pediatrics

Multiple epiphyseal dysplasia (MED) is most commonly associated with an autosomal dominant mutation in the COMP gene. What is the primary function of the protein encoded by this gene in the articular cartilage matrix?

. It forms the primary structural fibril of the cartilage matrix, providing tensile strength.
. It regulates the transport of sulfate into chondrocytes for proteoglycan synthesis.
. It is a pentameric glycoprotein that catalyzes collagen fibril assembly and stabilizes the extracellular matrix.
. It acts as a transcription factor for type II collagen expression in the growth plate.
. It degrades defective proteoglycans in the hypertrophic zone of the physis.

Correct Answer & Explanation

. It is a pentameric glycoprotein that catalyzes collagen fibril assembly and stabilizes the extracellular matrix.

Explanation

Correct Answer: CThe COMP (Cartilage Oligomeric Matrix Protein) gene encodes a pentameric non-collagenous glycoprotein that plays a crucial role in catalyzing collagen fibril assembly and stabilizing the extracellular matrix of cartilage. Mutations in COMP lead to the accumulation of misfolded proteins in the rough endoplasmic reticulum of chondrocytes, causing premature chondrocyte death and resulting in Multiple Epiphyseal Dysplasia (MED) or Pseudoachondroplasia. Type II collagen (Option A) provides tensile strength. Sulfate transport (Option B) is related to the SLC26A2 gene (diastrophic dysplasia/recessive MED).

Question 6475

Topic: Pediatric Hip
A 6-year-old child is evaluated for bilateral hip pain and a waddling gait. Radiographs show delayed, fragmented ossification of both capital femoral epiphyses. Which of the following radiographic findings would most strongly support a diagnosis of Multiple Epiphyseal Dysplasia (MED) rather than bilateral Legg-Calvé-Perthes disease?
. Unilateral subchondral crescent sign
. Metaphyseal cysts in the proximal femur
. A double-layered appearance of the patella on a lateral knee radiograph
. Severe platyspondyly of the thoracic spine
. Coxa magna deformity

Correct Answer & Explanation

. A double-layered appearance of the patella on a lateral knee radiograph

Explanation

Differentiating MED from bilateral Legg-Calvé-Perthes disease can be challenging as both present with fragmented, irregular capital femoral epiphyses. However, MED is a systemic dysplasia affecting multiple epiphyses. A classic radiographic hallmark of MED is the 'double patella' (a double-layered appearance of the patella on a lateral knee radiograph), which is seen in a significant percentage of patients. Severe platyspondyly (Option D) would suggest Spondyloepiphyseal Dysplasia (SED), as the spine is typically normal or only mildly affected in MED. Crescent signs and coxa magna are common in Perthes disease.

Question 6476

Topic: Pediatric Hip
A 2-year-old boy is incidentally found to have delayed and irregular ossification of the bilateral capital femoral epiphyses on a pelvic radiograph taken for a suspected swallowed coin. He has no limp, normal range of motion, and no pain. What is the most appropriate management for this orthopedic finding?
. Bilateral proximal femoral varus derotational osteotomies
. Application of an abduction orthosis
. Core decompression of the femoral heads
. Observation and reassurance
. Genetic testing for the COL2A1 mutation

Correct Answer & Explanation

. Observation and reassurance

Explanation

The clinical scenario describes Meyer dysplasia (dysplasia epiphysealis capitis femoris), which is characterized by delayed and irregular ossification of the capital femoral epiphyses. It typically presents incidentally in toddlers (usually around 2 years of age) and is bilateral in about 50% of cases. Unlike Legg-Calvé-Perthes disease, Meyer dysplasia is a benign, self-limiting condition that does not progress to avascular necrosis or collapse. Therefore, the most appropriate management is observation and reassurance. No surgical or orthotic intervention is required.

Question 6477

Topic: Pediatric Lower Extremity

While most forms of Multiple Epiphyseal Dysplasia (MED) are autosomal dominant, an autosomal recessive form exists due to mutations in the SLC26A2 gene (diastrophic dysplasia sulfate transporter). Which of the following clinical features is characteristic of this specific recessive variant and helps distinguish it from dominant MED?

. High incidence of retinal detachment
. Presence of clubfoot and cystic ear swelling
. Severe cervical kyphosis
. Asymmetric limb overgrowth
. Craniosynostosis

Correct Answer & Explanation

. Presence of clubfoot and cystic ear swelling

Explanation

Correct Answer: BMutations in the SLC26A2 gene cause a spectrum of recessive skeletal dysplasias, ranging from lethal achondrogenesis type IB to diastrophic dysplasia and recessive MED (rMED). Recessive MED is distinguished from dominant MED by the presence of features overlapping with diastrophic dysplasia, such as clubfoot (talipes equinovarus), cleft palate, and cystic swelling of the ear pinnae (cauliflower ear). Retinal detachment (Option A) is seen in COL2A1 mutations (SED). Cervical kyphosis (Option C) is classic for diastrophic dysplasia but less prominent in rMED, though clubfoot and ear findings are key differentiators for the SLC26A2 spectrum.

Question 6478

Topic: 4. Pediatrics

A 9-year-old boy presents with bilateral knee pain and a waddling gait. Radiographs reveal delayed, fragmented ossification centers of the proximal femurs and a characteristic 'double-layered' appearance of the patella on the lateral knee radiograph. He also has a history of bilateral clubfeet treated in infancy. Which of the following gene mutations is most likely responsible for this specific phenotype?

. COMP
. SLC26A2
. COL2A1
. MATN3
. FGFR3

Correct Answer & Explanation

. SLC26A2

Explanation

Correct Answer: B (SLC26A2)This patient presents with the classic features of autosomal recessive Multiple Epiphyseal Dysplasia (rMED). While most cases of MED are autosomal dominant (commonly involving the COMP gene), the recessive form is caused by mutations in the SLC26A2 gene (which encodes a sulfate transporter). A pathognomonic radiographic finding for rMED is the 'double-layered' patella. Patients also frequently present with clubfeet (talipes equinovarus) and cystic ear swellings (cauliflower ear). COL2A1 is associated with Spondyloepiphyseal Dysplasia (SED), and FGFR3 is associated with Achondroplasia.

Question 6479

Topic: Pediatric Hip
A 2-year-old boy is incidentally found to have delayed and granular ossification of the bilateral capital femoral epiphyses on a pelvic radiograph taken for a suspected urinary tract infection. He has no limp, no hip pain, and a completely normal range of motion. What is the most appropriate management for this orthopedic finding?
. Bilateral proximal femoral varus derotation osteotomies
. Application of an abduction orthosis (e.g., Atlanta brace)
. Core decompression of the femoral heads
. Observation and reassurance
. Genetic testing for COL2A1 mutation

Correct Answer & Explanation

. Observation and reassurance

Explanation

This presentation is highly characteristic of Meyer dysplasia (dysplasia epiphysealis capitis femoris). It is a benign, self-limiting condition characterized by delayed and irregular ossification of the capital femoral epiphysis. It is typically bilateral, asymptomatic, and discovered incidentally in toddlers. It is crucial to differentiate it from Legg-Calvé-Perthes disease, which usually presents later (ages 4-8) with pain and a limp. Meyer dysplasia requires no treatment and typically resolves with normal ossification by age 6.

Question 6480

Topic: 4. Pediatrics
A newborn female presents with asymmetric limb shortening, ichthyosiform skin lesions, and bilateral cataracts. Radiographs demonstrate widespread stippled calcifications in the epiphyses of the long bones and the spine. Which of the following is the most likely diagnosis?
. Rhizomelic chondrodysplasia punctata
. Conradi-Hünermann syndrome
. Multiple epiphyseal dysplasia
. Spondyloepiphyseal dysplasia congenita
. Achondroplasia

Correct Answer & Explanation

. Conradi-Hünermann syndrome

Explanation

The presence of stippled epiphyses (chondrodysplasia punctata) narrows the differential. Conradi-Hünermann syndrome is the X-linked dominant form of chondrodysplasia punctata. It is typically lethal in males, so it is seen almost exclusively in females. Classic features include asymmetric limb shortening, ichthyosis, cataracts, and stippled epiphyses. Rhizomelic chondrodysplasia punctata is autosomal recessive, presents with symmetric proximal limb shortening, and is usually lethal in the first year of life.

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