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1. General Principles & Basic Science MCQs

Practice Set 754 of 789

This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 15061

Topic: Biology, Genetics & Bone Healing

A 14-year-old boy presents with knee pain. Radiographs reveal a lytic lesion in the distal femoral epiphysis.

Biopsy is performed. Which histologic feature is diagnostic for this condition?

. Spindle cells arranged in a herringbone pattern
. Small blue round cells with CD99 positivity
. Bizarre multinucleated giant cells in a background of uniform stromal cells
. Extensive cartilage lobules with peripheral enchondral ossification
. Chondroblasts with longitudinal nuclear grooves and 'chicken-wire' calcifications

Correct Answer & Explanation

. Chondroblasts with longitudinal nuclear grooves and 'chicken-wire' calcifications

Explanation

The clinical and radiographic presentation is classic for a chondroblastoma. Histology characteristically shows mononuclear cells with longitudinal nuclear grooves (coffee bean nuclei) and a network of 'chicken-wire' intercellular calcifications.

Question 15062

Topic: Biology, Genetics & Bone Healing

A 14-year-old boy presents with right shoulder pain. Radiographs reveal a well-defined lytic lesion in the proximal humeral epiphysis.

Histology shows mononuclear cells with grooved nuclei and areas of fine, pericellular calcification. Which of the following is the most appropriate definitive management?

. Wide en bloc resection
. Extended intralesional curettage and bone grafting
. Preoperative radiation followed by excision
. Administration of denosumab
. Observation

Correct Answer & Explanation

. Extended intralesional curettage and bone grafting

Explanation

The clinical and histologic description is classic for chondroblastoma (epiphyseal lesion, coffee-bean nuclei, chicken-wire calcification). The gold standard treatment is extended intralesional curettage with high-speed burring of the walls, followed by bone grafting or cementation.

Question 15063

Topic: Biology, Genetics & Bone Healing

Which histological feature is considered classic for chondroblastoma when examining tissue from an epiphyseal lytic lesion in an adolescent?

. Extensive osteoid matrix production by atypical spindle cells
. Herringbone pattern of highly mitotic spindle cells
. Mononuclear cells with grooved nuclei and pericellular "chicken-wire" calcification
. Biphasic glandular and spindle cell components
. Physaliferous cells with extensive bubbly cytoplasm

Correct Answer & Explanation

. Mononuclear cells with grooved nuclei and pericellular "chicken-wire" calcification

Explanation

Chondroblastoma is classically characterized by polygonal mononuclear cells with grooved "coffee bean" nuclei and a fine network of pericellular "chicken-wire" calcifications. Osteoclast-like giant cells are also frequently interspersed.

Question 15064

Topic: 1. General Principles & Basic Science

Which of the following statements accurately reflects the epidemiology and etiology of Dysplasia Epiphysealis Hemimelica (DEH)?

. It is a common disorder with an incidence of 1 in 1,000.
. The etiology is strongly linked to a specific genetic mutation in the EXT1 gene.
. It affects males twice as frequently as females.
. The typical age of onset is in the third decade of life.
. It predominantly affects the upper extremities.

Correct Answer & Explanation

. It affects males twice as frequently as females.

Explanation

Correct Answer: CDEH is a very rare disorder with an incidence of 1 in 1,000,000. It affects males twice as frequently as females. The etiology remains unknown (unlike multiple hereditary exostoses which are linked to EXT genes). The age of onset is usually between 2 and 14 years, and it predominantly affects the lower extremities.

Question 15065

Topic: 1. General Principles & Basic Science

A 7-year-old male is brought to the orthopedic clinic by his parents. Which of the following constellations of symptoms is most consistent with a presentation of Dysplasia Epiphysealis Hemimelica (DEH)?

. Acute onset of severe pain, high fever, and a warm, erythematous joint
. A painless, soft, fluctuant mass that changes in size
. A bone-hard mass, joint deformity, aching pains, and limited range of motion
. Progressive muscle weakness, sensory loss, and absent deep tendon reflexes
. Multiple symmetric joint swellings with morning stiffness lasting over an hour

Correct Answer & Explanation

. A bone-hard mass, joint deformity, aching pains, and limited range of motion

Explanation

Correct Answer: CThe most common presenting symptoms of DEH include the presence of a mass with the consistency of bone, joint deformity, aching pains, and a limited range of motion due to the mechanical block caused by the epiphyseal overgrowth.

Question 15066

Topic: 1. General Principles & Basic Science

The images below show a lateral radiograph and a sagittal MRI of a knee in a young patient with aching pain and limited range of motion. The mass originates from the distal femoral epiphysis. Into which anatomical space is the bone mass predominantly protruding?




. Suprapatellar pouch
. Popliteal fossa
. Prepatellar bursa
. Anterior compartment of the leg
. Medial gutter of the knee

Correct Answer & Explanation

. Popliteal fossa

Explanation

Correct Answer: BThe sagittal MRI slide clearly shows a protruding bone mass extending posteriorly from the distal femoral epiphysis directly into the popliteal fossa. This posterior extension can cause significant mechanical block to knee flexion and aching pain.

Question 15067

Topic: 1. General Principles & Basic Science

Dysplasia epiphysealis hemimelica (DEH) is a rare developmental disorder. Which of the following best describes the epidemiological profile of this condition?

. Incidence of 1 in 10,000 with female predominance
. Incidence of 1 in 1,000,000 with male predominance
. Incidence of 1 in 100,000 with equal gender distribution
. Incidence of 1 in 1,000,000 with female predominance
. Incidence of 1 in 10,000 with male predominance

Correct Answer & Explanation

. Incidence of 1 in 1,000,000 with male predominance

Explanation

Correct Answer: Incidence of 1 in 1,000,000 with male predominanceDEH is an extremely rare skeletal developmental disorder with an estimated incidence of 1 in 1,000,000. Males are affected twice as frequently as females.

Question 15068

Topic: 1. General Principles & Basic Science

Regarding the age of onset for Dysplasia Epiphysealis Hemimelica (DEH), during which of the following age ranges do patients most commonly present with initial symptoms?

. Birth to 1 year
. 2 to 14 years
. 15 to 25 years
. 30 to 45 years
. Over 50 years

Correct Answer & Explanation

. 2 to 14 years

Explanation

Correct Answer: 2 to 14 yearsDEH is a developmental disorder affecting the epiphyses in young children. The age of onset is usually between 2 and 14 years, corresponding to the period of active epiphyseal growth and ossification.

Question 15069

Topic: 1. General Principles & Basic Science

Dysplasia epiphysealis hemimelica (DEH) is an extremely rare condition. According to epidemiological data, what is the estimated incidence of this disorder?

. 1 in 10,000
. 1 in 50,000
. 1 in 100,000
. 1 in 500,000
. 1 in 1,000,000

Correct Answer & Explanation

. 1 in 500,000

Explanation

Correct Answer: 1 in 1,000,000DEH is a very rare skeletal developmental disorder with an estimated incidence of 1 in 1,000,000 in the general population.

Question 15070

Topic: Infection, Pharmacology & VTE

A 9-year-old boy is evaluated for a mass around his ankle. Which of the following is NOT a typical presenting symptom or sign of Dysplasia Epiphysealis Hemimelica (DEH)?

. Aching pains
. Limited range of motion
. Joint deformity
. Mass with the consistency of bone
. Rapidly progressive overlying skin erythema and warmth

Correct Answer & Explanation

. Rapidly progressive overlying skin erythema and warmth

Explanation

Correct Answer: Rapidly progressive overlying skin erythema and warmthDEH typically presents with a bone-hard mass, deformity, aching pains, and limited range of motion. Rapidly progressive erythema and warmth are signs of acute inflammation or infection (e.g., osteomyelitis or septic arthritis) and are not characteristic of DEH.

Question 15071

Topic: 1. General Principles & Basic Science

A 9-year-old male presents with limited range of motion in the knee. Imaging is shown below. Which of the following statements is true regarding the epidemiology of this condition?


. Females are affected twice as frequently as males
. The incidence is approximately 1 in 10,000
. Males are affected twice as frequently as females
. It is exclusively found in the upper extremities
. It typically presents after skeletal maturity

Correct Answer & Explanation

. Males are affected twice as frequently as females

Explanation

Correct Answer: Males are affected twice as frequently as femalesThe images display DEH of the distal femoral epiphysis protruding into the popliteal fossa. DEH is a rare skeletal developmental disorder with an incidence of 1 in 1,000,000. Epidemiologically, males are affected twice as frequently as females.

Question 15072

Topic: 1. General Principles & Basic Science

The term 'hemimelica' in Dysplasia Epiphysealis Hemimelica refers to which of the following characteristic patterns of involvement?

. Involvement of exactly half of the body's skeleton
. Involvement of both the upper and lower limbs on one side
. Involvement of either the medial or lateral side of the epiphysis
. Involvement of the anterior half of the diaphysis
. Involvement of only the lower extremities

Correct Answer & Explanation

. Involvement of either the medial or lateral side of the epiphysis

Explanation

Correct Answer: Involvement of either the medial or lateral side of the epiphysisThe text explicitly states that characteristically the involvement is hemimelic, meaning that either the medial or the lateral epiphyseal side is involved, rather than the entire epiphysis symmetrically.

Question 15073

Topic: 1. General Principles & Basic Science

A 12-year-old boy presents with aching pain and limited range of motion in his knee. The imaging below reveals a protruding bone mass extending into the popliteal fossa. Which of the following is the most likely origin of this lesion?


. Distal femoral metaphysis
. Distal femoral diaphysis
. Distal femoral epiphysis
. Proximal tibial metaphysis
. Patellar articular surface

Correct Answer & Explanation

. Distal femoral epiphysis

Explanation

Correct Answer: CThe images demonstrate Dysplasia Epiphysealis Hemimelica (DEH) of the knee. By definition, DEH is a developmental disorder affecting the epiphyses. In this specific case, the protruding bone mass originates from the distal femoral epiphysis and extends into the popliteal fossa.

Question 15074

Topic: 1. General Principles & Basic Science

The term 'hemimelica' in Dysplasia Epiphysealis Hemimelica refers to which of the following characteristic patterns of involvement?

. Involvement of exactly half of the body's total epiphyses
. Involvement restricted to either the upper or lower extremity exclusively
. Involvement of only the medial or lateral side of the affected epiphysis
. Involvement of the epiphysis and metaphysis equally
. Involvement of the diaphysis sparing the epiphysis

Correct Answer & Explanation

. Involvement of only the medial or lateral side of the affected epiphysis

Explanation

Correct Answer: CThe term 'hemimelica' denotes that the involvement is characteristically limited to one half of the epiphysisโ€”either the medial or the lateral epiphyseal side is involved, leading to asymmetric growth and deformity.

Question 15075

Topic: 1. General Principles & Basic Science

A resident is reviewing a case series of patients with Dysplasia Epiphysealis Hemimelica (DEH). Based on the established epidemiological profile of this disorder, which of the following demographic presentations is most typical?

. A 1-year-old female
. A 8-year-old male
. A 16-year-old female
. A 25-year-old male
. A 40-year-old female

Correct Answer & Explanation

. A 8-year-old male

Explanation

Correct Answer: BDEH typically affects young children, with the age of onset usually between 2 and 14 years. Furthermore, males are affected twice as frequently as females. Therefore, an 8-year-old male fits the classic demographic profile perfectly.

Question 15076

Topic: 1. General Principles & Basic Science

A 5-year-old boy is incidentally found to have an irregular calcified mass arising from the lateral aspect of the proximal tibial epiphysis. He has full range of motion, no pain, and no angular deformity. What is the most appropriate initial management?

. Immediate wide surgical excision
. Curettage and bone grafting
. Clinical and radiographic observation
. Epiphysiodesis of the unaffected side
. Neoadjuvant chemotherapy followed by resection

Correct Answer & Explanation

. Clinical and radiographic observation

Explanation

In asymptomatic cases of DEH without joint impingement or deformity, the standard of care is clinical and radiographic observation. Surgical intervention is reserved for symptomatic patients or those with progressive mechanical block.

Question 15077

Topic: 1. General Principles & Basic Science

In patients diagnosed with Dysplasia Epiphysealis Hemimelica, the term 'hemimelica' specifically refers to which characteristic clinical feature?

. The condition affects only half of the body symmetrically.
. The lesion is typically confined to either the medial or lateral half of the affected limb/joint.
. The lesion typically involves the proximal half of long bones.
. The disease typically presents in only one hemisphere of the brain as a comorbidity.
. The overgrowth stops at half the normal bone length.

Correct Answer & Explanation

. The lesion is typically confined to either the medial or lateral half of the affected limb/joint.

Explanation

The term 'hemimelica' describes the classic distribution of the disease, which typically affects either the medial (more common) or lateral half of a single limb. It rarely crosses the midline of the affected joint.

Question 15078

Topic: Biology, Genetics & Bone Healing

Which zone of the epiphyseal cartilage is theorized to be the origin of the abnormal proliferation in Dysplasia Epiphysealis Hemimelica?

. Zone of provisional calcification
. Hypertrophic zone
. Germinal/Resting zone of the epiphyseal cartilage
. Primary spongiosa
. Secondary spongiosa

Correct Answer & Explanation

. Germinal/Resting zone of the epiphyseal cartilage

Explanation

DEH is believed to result from an abnormal proliferation of the epiphyseal cartilage cells, functioning similarly to an ectopic germinal/resting zone that produces enchondral ossification outward.

Question 15079

Topic: 1. General Principles & Basic Science

Dysplasia Epiphysealis Hemimelica (DEH) is characterized by asymmetric cartilaginous overgrowth. Which of the following best describes the most common anatomical distribution of this disease?

. Bilateral and symmetrical involvement of the upper limbs
. Metaphyseal region of the long bones universally
. Medial aspect of the lower extremities
. Lateral aspect of the upper extremities
. Diffuse involvement of the axial skeleton

Correct Answer & Explanation

. Medial aspect of the lower extremities

Explanation

DEH almost exclusively affects the lower extremities in an asymmetrical, unilateral fashion. The lesions most frequently arise from the medial half of the epiphysis (hemimelic).

Question 15080

Topic: 1. General Principles & Basic Science

Which of the following imaging modalities is considered the most accurate for delineating the unossified cartilage cap and determining the extent of articular surface involvement in DEH?

. Ultrasound
. Computed Tomography (CT)
. Magnetic Resonance Imaging (MRI)
. Positron Emission Tomography (PET)
. Radionuclide bone scan

Correct Answer & Explanation

. Magnetic Resonance Imaging (MRI)

Explanation

MRI is the gold standard for evaluating DEH as it precisely delineates the unossified cartilage cap, evaluates its continuity with the parent epiphysis, and maps out articular surface involvement.

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