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4. Pediatrics MCQs

Practice Set 211 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 4201

Topic: 4. Pediatrics

Congenital spondyloepiphyseal dysplasia is caused by a mutation in the COL2A1 gene. This mutation primarily affects the synthesis of which of the following structural proteins?

. Type I procollagen
. Type II procollagen
. Type IX collagen
. Type X collagen
. Elastin

Correct Answer & Explanation

. Type II procollagen

Explanation

Correct Answer: Type II procollagenThe COL2A1 gene encodes type II procollagen, which is the major collagenous component of articular cartilage and the nucleus pulposus of intervertebral discs. Mutations in this gene lead to the defective cartilage matrix seen in SEDC.

Question 4202

Topic: 4. Pediatrics

A key differentiating factor between Spondyloepiphyseal Dysplasia Congenita (SEDC) and Spondyloepiphyseal Dysplasia Tarda (SEDT) is their genetic inheritance and onset. Which of the following is true regarding SEDT?

. It is an autosomal dominant disorder presenting at birth.
. It is an X-linked recessive disorder that manifests in childhood.
. It is caused by a COL2A1 mutation and presents with severe atlantoaxial instability at birth.
. It affects females predominantly and causes severe coxa valga.
. It is characterized by normal trunk length but severely shortened limbs.

Correct Answer & Explanation

. It is an X-linked recessive disorder that manifests in childhood.

Explanation

Correct Answer: It is an X-linked recessive disorder that manifests in childhood.SEDT is an X-linked recessive disorder that manifests later in childhood, unlike SEDC, which is congenital (present at birth) and typically caused by an autosomal dominant mutation in the COL2A1 gene. SEDT affects males exclusively and leads to progressive osteochondrodysplasia.

Question 4203

Topic: 4. Pediatrics

A 4-year-old child presents with disproportionate short stature, a short trunk, and epiphyseal dysplasia of the femoral heads. Genetic testing reveals a mutation in the COL2A1 gene. Which of the following proteins is primarily affected in this condition?

. Type I collagen
. Type II procollagen
. Fibroblast growth factor receptor 3 (FGFR3)
. Cartilage oligomeric matrix protein (COMP)

Correct Answer & Explanation

. Type II procollagen

Explanation

Correct Answer: Type II procollagenSpondyloepiphyseal dysplasia (SED) congenita is caused by a mutation in the COL2A1 gene, which encodes for type II procollagen. This leads to defective cartilage formation, resulting in the characteristic short trunk, platyspondyly, and epiphyseal dysplasia.

Question 4204

Topic: 4. Pediatrics

Review the lateral radiograph of the thoracolumbar spine of a 17-year-old boy presenting with progressive dorsolumbar kyphosis.



Based on the characteristic vertebral morphology shown, what is the most likely diagnosis?

. Achondroplasia
. Spondyloepiphyseal dysplasia
. Mucopolysaccharidosis type IV (Morquio syndrome)
. Osteogenesis imperfecta

Correct Answer & Explanation

. Spondyloepiphyseal dysplasia

Explanation

Correct Answer: Spondyloepiphyseal dysplasiaThe radiograph demonstrates platyspondyly and the typical 'champagne-bottle' shaped vertebral bodies, which are hallmark radiographic features of Spondyloepiphyseal dysplasia (SED). Achondroplasia typically presents with posterior scalloping and narrowing of interpedicular distances, while Morquio syndrome features anterior central beaking.

Question 4205

Topic: Pediatric Hip

A 28-year-old female with a known skeletal dysplasia presents with hip pain. Her pelvic radiograph is shown below.



Which of the following best describes the characteristic proximal femoral deformity seen in this condition during adulthood?

. Coxa valga with a widened femoral neck
. Coxa vara with retarded ossification of the proximal femur
. Slipped capital femoral epiphysis
. Avascular necrosis of the femoral head with fragmentation

Correct Answer & Explanation

. Coxa vara with retarded ossification of the proximal femur

Explanation

Correct Answer: Coxa vara with retarded ossification of the proximal femurIn Spondyloepiphyseal dysplasia, there is retarded ossification of the proximal femur in youth, which typically progresses to coxa vara in adulthood, as demonstrated in the provided radiograph.

Question 4206

Topic: 4. Pediatrics

Which of the following clinical profiles is most characteristic of Spondyloepiphyseal Dysplasia Tarda?

. Proportionate short stature with normal spine alignment
. Disproportionate short stature with a short trunk, short neck, and broad chest manifesting in childhood
. Disproportionate short stature with rhizomelic limb shortening and a normal trunk length
. Normal stature at birth with progressive limb bowing and multiple fractures

Correct Answer & Explanation

. Disproportionate short stature with a short trunk, short neck, and broad chest manifesting in childhood

Explanation

Correct Answer: Disproportionate short stature with a short trunk, short neck, and broad chest manifesting in childhoodSED tarda manifests in childhood with disproportionate short stature, a short neck and trunk, and a broad chest. The short stature is primarily due to a growth disorder of the spine (short trunk), unlike achondroplasia which features rhizomelic limb shortening with a relatively normal trunk.

Question 4207

Topic: 4. Pediatrics

A 14-year-old male presents with worsening hip pain and early-onset hip osteoarthritis. He has short stature with a disproportionately short trunk. Radiographs reveal a "heaped up" appearance of the posterior portion of the vertebral endplates. What is the most likely diagnosis?

. Achondroplasia
. Spondyloepiphyseal dysplasia congenita
. Spondyloepiphyseal dysplasia tarda
. Multiple epiphyseal dysplasia
. Pseudoachondroplasia

Correct Answer & Explanation

. Spondyloepiphyseal dysplasia tarda

Explanation

Spondyloepiphyseal dysplasia (SED) tarda typically presents in late childhood or adolescence in males (X-linked recessive). Radiographs characteristically show a "heaped-up" appearance at the posterior third of the vertebral bodies.

Question 4208

Topic: Pediatric Hip

A patient with spondyloepiphyseal dysplasia congenita is noted to have severe, progressive coxa vara. If surgical intervention is planned, what is the primary goal of the recommended procedure?

. To deepen the acetabulum
. To perform a proximal femoral varus osteotomy
. To perform a subtrochanteric valgus producing osteotomy
. To fuse the hip joint
. To lengthen the femur

Correct Answer & Explanation

. To perform a subtrochanteric valgus producing osteotomy

Explanation

Coxa vara is a hallmark of SEDC due to delayed ossification of the femoral neck. A subtrochanteric valgus osteotomy is indicated to correct the neck-shaft angle, improve abductor mechanics, and promote ossification of the femoral neck.

Question 4209

Topic: Pediatric Hip

Spondyloepiphyseal dysplasia (SED) can present similarly to Morquio syndrome. Which of the following clinical features most reliably distinguishes SED congenita from Morquio syndrome?

. Presence of atlantoaxial instability
. Short trunk dwarfism
. Absence of corneal clouding and normal mucopolysaccharides
. Presence of coxa vara
. Flattened vertebral bodies (platyspondyly)

Correct Answer & Explanation

. Absence of corneal clouding and normal mucopolysaccharides

Explanation

Both conditions feature short trunk dwarfism, platyspondyly, and odontoid hypoplasia. However, Morquio syndrome is a mucopolysaccharidosis characterized by keratan sulfate excretion and corneal clouding, which are absent in SEDC.

Question 4210

Topic: 4. Pediatrics

Which of the following non-orthopedic specialists is most essential in the routine multidisciplinary surveillance of a child with spondyloepiphyseal dysplasia congenita (SEDC)?

. Cardiologist
. Ophthalmologist
. Endocrinologist
. Nephrologist
. Gastroenterologist

Correct Answer & Explanation

. Ophthalmologist

Explanation

Because type II collagen is a major structural component of the vitreous humor, patients with SEDC are at high risk for severe myopia and retinal detachment. Regular ophthalmologic screening is essential.

Question 4211

Topic: 4. Pediatrics

You are evaluating a newborn with a disproportionately short trunk, flat face, and cleft palate. Radiographs show absent ossification centers for the pubic bones, distal femoral epiphyses, and proximal tibial epiphyses. What is the most likely diagnosis?

. Achondroplasia
. Multiple epiphyseal dysplasia
. Spondyloepiphyseal dysplasia congenita
. Diastrophic dysplasia
. Osteogenesis imperfecta

Correct Answer & Explanation

. Spondyloepiphyseal dysplasia congenita

Explanation

SEDC presents at birth with short trunk dwarfism and delayed ossification. The delayed appearance of the pubic bones, distal femoral, and proximal tibial epiphyses (which are normally present at birth) is a classic radiographic hallmark.

Question 4212

Topic: 4. Pediatrics

A 12-year-old boy presents with progressive hip pain. Radiographs show flattened femoral heads and early degenerative changes, but his spine radiographs are entirely normal. Which of the following is the most likely diagnosis?

. Spondyloepiphyseal dysplasia congenita
. Spondyloepiphyseal dysplasia tarda
. Multiple epiphyseal dysplasia
. Pseudoachondroplasia
. Achondroplasia

Correct Answer & Explanation

. Multiple epiphyseal dysplasia

Explanation

Multiple epiphyseal dysplasia (MED) affects the epiphyses resulting in early osteoarthritis (especially hips and knees), but crucially involves a normal or near-normal spine, distinguishing it from the spondyloepiphyseal dysplasias.

Question 4213

Topic: 4. Pediatrics

What is the genetic mutation associated with Spondyloepiphyseal Dysplasia (SED) tarda?

. FGFR3
. COL2A1
. TRAPPC2 (SEDL)
. COMP
. COL1A1

Correct Answer & Explanation

. TRAPPC2 (SEDL)

Explanation

SED tarda is an X-linked recessive disorder caused by mutations in the TRAPPC2 gene (formerly SEDL), which is involved in vesicular transport from the endoplasmic reticulum to the Golgi apparatus.

Question 4214

Topic: 4. Pediatrics

A 7-year-old child with spondyloepiphyseal dysplasia congenita presents with a waddling gait. Radiographs demonstrate an abnormal neck-shaft angle of 90 degrees with a vertical physeal orientation. Which complication is most likely if this is left untreated?

. Avascular necrosis of the femoral head
. Progressive coxa vara and premature osteoarthritis
. Developmental dysplasia of the hip
. Slipped capital femoral epiphysis
. Femoral shaft stress fracture

Correct Answer & Explanation

. Progressive coxa vara and premature osteoarthritis

Explanation

The child has severe coxa vara (neck-shaft angle < 120 degrees). If left untreated, the abnormal biomechanical stresses will lead to progressive varus deformity, nonunion of the femoral neck, and premature hip osteoarthritis.

Question 4215

Topic: 4. Pediatrics

Spondyloepiphyseal dysplasia congenita is characterized by a defect in Type II collagen. Which of the following conditions shares the same underlying defective protein?

. Kniest dysplasia
. Osteogenesis imperfecta
. Cleidocranial dysplasia
. Marfan syndrome
. Campomelic dysplasia

Correct Answer & Explanation

. Kniest dysplasia

Explanation

Kniest dysplasia, Stickler syndrome, and Spondyloepiphyseal dysplasia congenita are all type II collagenopathies caused by mutations in the COL2A1 gene. They share common features like cleft palate, myopia, and epiphyseal changes.

Question 4216

Topic: 4. Pediatrics

Which of the following best describes the classical radiographic appearance of the pelvis and hips in an infant with Spondyloepiphyseal Dysplasia Congenita (SEDC)?

. Champagne glass pelvis with narrow sacrosciatic notch
. Squared iliac wings and trident acetabulum
. Delayed ossification of the pubis and femoral heads
. Acetabular protrusion (protrusio acetabuli)
. Multiple exostoses around the pelvic brim

Correct Answer & Explanation

. Delayed ossification of the pubis and femoral heads

Explanation

SEDC is characterized by significantly delayed ossification. Radiographs in infants show absent or severely delayed ossification of the pubic bones and femoral capital epiphyses. The "champagne glass" pelvis is seen in achondroplasia.

Question 4217

Topic: 4. Pediatrics
A 3-year-old child presents with disproportionate short trunk dwarfism, a cleft palate, and a waddling gait. Radiographs reveal coxa vara and delayed ossification of the femoral heads. Genetic testing confirms a mutation in the COL2A1 gene. Which type of collagen is primarily defective in this patient?
. Type I
. Type II
. Type III
. Type IV
. Type X

Correct Answer & Explanation

. Type II

Explanation

Spondyloepiphyseal Dysplasia Congenita (SEDC) is caused by a mutation in the COL2A1 gene, resulting in defective Type II collagen. Type II collagen is a major structural component of hyaline cartilage, affecting the epiphyses and spine.

Question 4218

Topic: 4. Pediatrics

Which of the following genes is responsible for X-linked Spondyloepiphyseal Dysplasia Tarda?

. TRAPPC2
. COL2A1
. FGFR3
. COMP
. SOX9

Correct Answer & Explanation

. TRAPPC2

Explanation

X-linked SED Tarda is caused by mutations in the TRAPPC2 gene (formerly known as SEDL), which is involved in vesicular transport from the endoplasmic reticulum to the Golgi apparatus.

Question 4219

Topic: 4. Pediatrics

A 4-year-old child presents with short trunk dwarfism and a waddling gait. Radiographs show universal platyspondyly. The patient has a cleft palate and clear corneas on eye examination. Unlike Morquio syndrome, which can present similarly, this patient's condition is primarily caused by a mutation in:

. COL1A1
. COMP
. FGFR3
. COL2A1
. GALNS

Correct Answer & Explanation

. COL2A1

Explanation

The presence of short trunk dwarfism, clear corneas, and a cleft palate suggests SED Congenita (COL2A1 mutation). Morquio syndrome presents with corneal clouding and is caused by a lysosomal enzyme deficiency (e.g., GALNS).

Question 4220

Topic: Pediatric Hip

A 6-year-old boy with Spondyloepiphyseal Dysplasia Congenita is noted to have a progressively worsening waddling gait. Pelvic radiographs reveal bilateral coxa vara with a Hilgenreiner-epiphyseal angle (HEA) of 65 degrees. What is the most appropriate management?

. Observation and physical therapy
. Valgus-producing proximal femoral osteotomy
. Varus-producing proximal femoral osteotomy
. In situ pinning of the capital femoral epiphysis
. Spica cast application

Correct Answer & Explanation

. Valgus-producing proximal femoral osteotomy

Explanation

In children with SED Congenita, progressive coxa vara with a Hilgenreiner-epiphyseal angle greater than 60 degrees is an indication for a valgus-producing subtrochanteric osteotomy. This converts shear forces into compressive forces, promoting healing and preventing nonunion.

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