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4. Pediatrics MCQs

Practice Set 330 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 6581

Topic: 4. Pediatrics



Reviewing a hand radiograph of a child with TRPS Type 1, the physician notes characteristic cone-shaped epiphyses. Which joints are most classically affected by this specific epiphyseal malformation in TRPS?

. Metacarpophalangeal (MCP) joints
. Proximal interphalangeal (PIP) joints
. Distal interphalangeal (DIP) joints
. Radiocarpal joints
. Carpometacarpal (CMC) joints

Correct Answer & Explanation

. Proximal interphalangeal (PIP) joints

Explanation

In Trichorhinophalangeal Syndrome (TRPS), cone-shaped epiphyses predominantly affect the middle phalanges at the proximal interphalangeal (PIP) joints, often causing angular deformities of the fingers.

Question 6582

Topic: Pediatric Hip

A 10-year-old boy diagnosed with Trichorhinophalangeal Syndrome (TRPS) Type 1 presents with right hip pain and a limp. Pelvic radiographs show flattening and fragmentation of the right capital femoral epiphysis. This orthopedic manifestation of TRPS Type 1 most closely mimics which of the following conditions?

. Slipped capital femoral epiphysis
. Developmental dysplasia of the hip
. Legg-Calve-Perthes disease
. Coxa vara
. Femoroacetabular impingement

Correct Answer & Explanation

. Legg-Calve-Perthes disease

Explanation

TRPS Type 1 is characterized by a high incidence of avascular necrosis-like changes in the capital femoral epiphysis. This closely mimics Legg-Calve-Perthes disease and frequently leads to early-onset secondary osteoarthritis.

Question 6583

Topic: Pediatric Hip

An 8-year-old boy presents with a painful limp. Physical examination reveals fine sparse hair, a pear-shaped nose, and brachydactyly.

Hand radiographs show cone-shaped epiphyses. Which of the following hip pathologies is most characteristic of this patient's syndrome?

. Slipped capital femoral epiphysis
. Legg-Calve-Perthes-like avascular necrosis
. Developmental dysplasia of the hip
. Primary synovial chondromatosis
. Coxa vara

Correct Answer & Explanation

. Legg-Calve-Perthes-like avascular necrosis

Explanation

Trichorhinophalangeal syndrome (TRPS) Type 1 frequently presents with craniofacial abnormalities, sparse hair, and cone-shaped phalangeal epiphyses. The hallmark major joint manifestation is premature osteoarthritis secondary to Legg-Calve-Perthes-like avascular necrosis of the femoral heads.

Question 6584

Topic: 4. Pediatrics
A patient with Pseudoachondroplasia presents with significant genu varum. Unlike Achondroplasia, which of the following clinical features is typically absent in Pseudoachondroplasia?
. Short stature
. Ligamentous laxity
. Craniofacial abnormalities
. Epiphyseal involvement
. Early-onset osteoarthritis

Correct Answer & Explanation

. Craniofacial abnormalities

Explanation

Pseudoachondroplasia is caused by mutations in the COMP gene. While it shares short stature with Achondroplasia, patients with Pseudoachondroplasia have a normal craniofacial appearance (no frontal bossing or midface hypoplasia). They also exhibit significant joint laxity and severe epiphyseal/metaphyseal changes leading to early arthritis.

Question 6585

Topic: Pediatric Hip
A 4-year-old child presents with a waddling gait. Radiographs show delayed ossification of the femoral heads with a fragmented appearance, but the acetabulum is normal and the child is otherwise healthy and of normal height. What is the most likely diagnosis?
. Legg-Calvé-Perthes disease
. Multiple Epiphyseal Dysplasia (Fairbank type)
. Meyer's dysplasia
. Spondyloepiphyseal dysplasia tarda
. Avascular necrosis secondary to steroids

Correct Answer & Explanation

. Meyer's dysplasia

Explanation

Meyer's dysplasia (dysplasia of the femoral capital epiphysis) is a benign variant of epiphyseal development. It often mimics Legg-Calvé-Perthes disease but occurs in younger children (2-4 years), is often bilateral, and typically resolves spontaneously without the significant collapse or deformity seen in Perthes.

Question 6586

Topic: 4. Pediatrics
A 7-year-old child presents with asymmetric overgrowth of the medial aspect of the distal femoral epiphysis. The lesion appears as an osteocartilaginous mass arising from the epiphysis. What is the most likely diagnosis?
. Ollier disease
. Trevor's disease (Dysplasia Epiphysealis Hemimelica)
. Meyer's dysplasia
. Blount's disease
. Legg-Calvé-Perthes disease

Correct Answer & Explanation

. Trevor's disease (Dysplasia Epiphysealis Hemimelica)

Explanation

Trevor's disease, or Dysplasia Epiphysealis Hemimelica (DEH), is a rare developmental disorder characterized by asymmetric overgrowth of one or more epiphyses. It most commonly affects the lower limb (talus, distal femur, or proximal tibia) and is usually confined to one side of the joint (medial more common than lateral).

Question 6587

Topic: 4. Pediatrics
A 14-year-old girl presents with bilateral wrist pain and restricted range of motion. Radiographs demonstrate a V-shaped proximal carpal row, dorsal prominence of the distal ulna, and excessive volar and ulnar tilt of the distal radius. A mutation in which of the following genes is most strongly associated with this isolated skeletal dysplasia?
. EXT1
. FGFR3
. SHOX
. COMP
. COL1A1

Correct Answer & Explanation

. SHOX

Explanation

The patient has Madelung deformity, which is characterized by premature closure of the volar-ulnar distal radial physis. It is strongly associated with mutations in the SHOX gene, especially in the context of Léri-Weill dyschondrosteosis or Turner syndrome.

Question 6588

Topic: 4. Pediatrics

A newborn is evaluated for a right lower extremity deformity. Examination reveals a shortened right leg, anteromedial bowing of the tibia, skin dimpling over the anterior crest, and a foot with three toes in marked equinovalgus. What is the most likely diagnosis?

. Fibular hemimelia
. Tibial hemimelia
. Congenital pseudarthrosis of the tibia
. Campomelic dysplasia
. Proximal focal femoral deficiency

Correct Answer & Explanation

. Fibular hemimelia

Explanation

Fibular hemimelia is the most common congenital long bone deficiency and classically presents with anteromedial tibial bowing, absent lateral rays (toes), and an equinovalgus foot. Tibial hemimelia typically presents with a varus foot and preaxial polydactyly.

Question 6589

Topic: Pediatric Lower Extremity

In a patient diagnosed with Proximal Focal Femoral Deficiency (PFFD), which of the following clinical factors is the most critical determinant when deciding between a reconstructive limb-lengthening program versus an early amputation with rotationplasty?

. Presence of an intact fibula
. Predicted limb length discrepancy at skeletal maturity
. Age at initial presentation
. Severity of the knee flexion contracture
. Presence of an omovertebral connection

Correct Answer & Explanation

. Predicted limb length discrepancy at skeletal maturity

Explanation

The predicted limb length discrepancy (LLD) at skeletal maturity dictates surgical management in PFFD. A predicted LLD greater than 20 cm typically necessitates amputation or rotationplasty, whereas discrepancies less than 20 cm may be amenable to staged lengthening procedures.

Question 6590

Topic: 4. Pediatrics

A 3-year-old girl presents with a painless, palpable midshaft mass over her left clavicle. Radiographs reveal a complete defect with smooth, rounded, and sclerotic bone ends. If surgical intervention is deferred, what systemic or organic condition MUST be ruled out given the laterality of this lesion?

. Neurofibromatosis type 1
. Dextrocardia
. Cleidocranial dysplasia
. Holt-Oram syndrome
. Poland syndrome

Correct Answer & Explanation

. Dextrocardia

Explanation

Congenital pseudarthrosis of the clavicle almost exclusively occurs on the right side due to normal subclavian artery pulsation affecting embryonic development. If it occurs on the left side, dextrocardia or situs inversus must be investigated.

Question 6591

Topic: Pediatric Upper Extremity & Spine

A newborn has bilateral radially deviated hands and shortened forearms. Radiographs show bilateral absent radii. On physical examination, the thumbs are present and morphologically normal. Which underlying hematologic abnormality is most closely associated with this specific presentation?

. Aplastic anemia
. Thrombocytopenia
. Leukemia
. Sickle cell trait
. Hemophilia A

Correct Answer & Explanation

. Thrombocytopenia

Explanation

Thrombocytopenia Absent Radius (TAR) syndrome is distinguished from other radial longitudinal deficiencies (like Fanconi anemia) by the presence of a normal thumb. It is associated with severe, often transient, thrombocytopenia in infancy.

Question 6592

Topic: 4. Pediatrics

An 8-month-old infant is referred for a noticeable anterolateral bow of the distal tibia. Radiographs demonstrate focal diaphyseal sclerosis and cortical thickening at the apex of the curve without an obvious fracture. To prevent the most dreaded complication associated with this deformity, what is the best initial management strategy?

. Immediate prophylactic intramedullary rodding
. Observation with serial radiographs every 6 months
. Total contact orthotic bracing
. Corrective osteotomy and plate fixation
. Epiphysiodesis of the contralateral limb

Correct Answer & Explanation

. Total contact orthotic bracing

Explanation

Anterolateral bowing of the tibia is highly associated with Neurofibromatosis type 1 and frequently progresses to congenital pseudarthrosis of the tibia if a fracture occurs. Prophylactic total contact bracing is the initial standard of care to protect the bone from fracturing.

Question 6593

Topic: 4. Pediatrics

A 6-year-old girl is evaluated for a disproportionately large index and middle finger on her right hand. MRI reveals extensive fibroadipose tissue proliferation infiltrating the median nerve territory, accompanied by osseous enlargement. What somatic mutation is most commonly implicated in this localized gigantism?

. PIK3CA
. SHOX
. FGFR3
. COL2A1
. RUNX2

Correct Answer & Explanation

. PIK3CA

Explanation

Macrodystrophia lipomatosa is a form of localized gigantism characterized by fibrofatty overgrowth, classically restricted to the territory of a major nerve (median or plantar). It is a part of the PIK3CA-related overgrowth spectrum (PROS) caused by somatic mosaic PIK3CA mutations.

Question 6594

Topic: 4. Pediatrics

A 4-year-old boy demonstrates a painless, bilateral inability to supinate his forearms. Radiographs reveal an osseous connection between the proximal radius and ulna. This congenital anomaly is a result of a failure of longitudinal segmentation during which period of embryonic development?

. 2nd to 3rd week of gestation
. 5th to 8th week of gestation
. 12th to 16th week of gestation
. 20th to 24th week of gestation
. Postnatal period before physeal closure

Correct Answer & Explanation

. 5th to 8th week of gestation

Explanation

Congenital radioulnar synostosis results from a failure of longitudinal segmentation of the common cartilaginous precursor of the radius and ulna. This embryological differentiation normally occurs between the 5th and 8th weeks of gestation.

Question 6595

Topic: 4. Pediatrics

A 2-year-old boy presents with unilateral tibia vara. Radiographs reveal a well-defined radiolucency with surrounding cortical sclerosis in the medial cortex of the proximal tibial metaphysis. What is the most appropriate next step in management?

. Proximal tibial osteotomy
. MRI to rule out malignancy
. Curettage and bone grafting
. Observation
. Guided growth via hemi-epiphysiodesis

Correct Answer & Explanation

. Observation

Explanation

Focal fibrocartilaginous dysplasia is a benign condition characterized by a radiolucent lesion in the medial tibial cortex causing unilateral bowleg. The vast majority of cases resolve spontaneously with observation as the child grows.

Question 6596

Topic: 4. Pediatrics

A patient with delayed cranial suture closure and bilateral clavicular hypoplasia is diagnosed with a RUNX2 gene mutation. Which of the following is the most common orthopedic complication in this condition that may require surgical correction?

. Spondylolisthesis
. Coxa vara
. Genu valgum
. Atlantoaxial instability
. Tarsal coalition

Correct Answer & Explanation

. Coxa vara

Explanation

Cleidocranial dysplasia involves defective intramembranous ossification but also has enchondral defects, particularly in the pelvis. Coxa vara is a frequent, progressive complication that often requires surgical correction via a valgus-producing proximal femoral osteotomy.

Question 6597

Topic: 4. Pediatrics

An 8-year-old boy presents with a short neck, low posterior hairline, and restricted cervical motion. Cervical radiographs confirm congenital fusion of C3-C4. What is the most critical screening evaluation to perform upon initial diagnosis?

. Echocardiogram
. Renal ultrasound
. Pulmonary function testing
. Ophthalmologic exam
. Audiogram

Correct Answer & Explanation

. Renal ultrasound

Explanation

Klippel-Feil syndrome is defined by congenital fusion of cervical vertebrae and is heavily associated with significant visceral anomalies. Genitourinary tract abnormalities occur in up to 30% of patients, making a screening renal ultrasound mandatory.

Question 6598

Topic: Pediatric Upper Extremity & Spine
A newborn is evaluated for bilateral absent thumbs and severe radial longitudinal deficiency. Which genetic condition should be suspected, and what specific systemic screening is indicated?
. TAR syndrome; complete blood count
. Holt-Oram syndrome; echocardiogram
. VACTERL association; renal ultrasound
. Fanconi anemia; chromosomal breakage test
. Diamond-Blackfan anemia; bone marrow biopsy

Correct Answer & Explanation

. Holt-Oram syndrome; echocardiogram

Explanation

Holt-Oram syndrome (TBX5 mutation) is characterized by upper limb anomalies, notably absent or hypoplastic thumbs, along with congenital heart defects like atrial septal defects. The absence of thumbs clearly distinguishes it from TAR syndrome, where the thumbs are classically present.

Question 6599

Topic: 4. Pediatrics

A newborn infant presents with a "mirror hand" deformity characterized by duplication of the ulna, an absent radius, and seven fingers. What developmental signaling center is duplicated to cause this condition?

. Apical ectodermal ridge (AER)
. Wnt signaling pathway
. Zone of polarizing activity (ZPA)
. Progress zone
. Dorsal ectoderm

Correct Answer & Explanation

. Zone of polarizing activity (ZPA)

Explanation

Ulnar dimelia is a rare congenital anomaly resulting from duplication of the Zone of Polarizing Activity (ZPA). The ZPA secretes Sonic hedgehog (SHH) protein, which directs the anterior-posterior (radioulnar) axis formation of the developing limb.

Question 6600

Topic: 4. Pediatrics

A 13-year-old girl presents with bilateral wrist deformities and mesomelic short stature. Radiographs demonstrate volar and ulnar bowing of the distal radius with a prominent dorsal distal ulna. A mutation in which of the following genes is predominantly associated with this presentation?

. FGFR3
. SOX9
. SHOX
. COMP
. COL1A1

Correct Answer & Explanation

. SHOX

Explanation

Leri-Weill dyschondrosteosis is characterized by a Madelung deformity and mesomelic short stature. It is caused by a haploinsufficiency mutation or deletion in the SHOX gene, located on the pseudoautosomal region of the sex chromosomes.

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