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Bone Tumors MCQs

Practice Set 34 of 52

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

Question 661

Topic: Bone Tumors

A 15-year-old boy has an osteochondroma of the distal radius causing ulnar deviation of the hand and wrist. What is the most appropriate surgical approach to address this angular deformity?

. Simple excision of the osteochondroma with no further intervention
. Osteochondroma excision followed by contralateral growth plate stimulation
. Osteochondroma excision combined with corrective osteotomy and possibly guided growth
. Observation until skeletal maturity, then excision
. Amputation of the affected limb

Correct Answer & Explanation

. Osteochondroma excision combined with corrective osteotomy and possibly guided growth

Explanation

When an osteochondroma causes significant angular deformity, especially in a skeletally immature patient, simple excision may not correct the existing deformity. The most appropriate approach often involves excision of the osteochondroma combined with a corrective osteotomy and potentially guided growth (e.g., hemiepiphysiodesis) to address the underlying physeal disturbance and realign the limb. Observation will allow the deformity to worsen. Amputation is extreme. Contralateral growth plate stimulation is not the primary treatment for ipsilateral deformity correction.

Question 662

Topic: Bone Tumors

What is the typical direction of growth for a pedunculated osteochondroma relative to the adjacent joint?

. Towards the joint
. Parallel to the joint surface
. Away from the joint
. Variable, no typical direction
. Into the joint space

Correct Answer & Explanation

. Away from the joint

Explanation

A classic feature of osteochondromas is that they typically point or grow away from the adjacent joint. This is thought to be due to the migration of physeal cartilage cells away from the growth plate in the direction of muscle pull or fascial attachments. This orientation helps differentiate it from other lesions.

Question 663

Topic: Bone Tumors

What type of cartilage typically forms the cap of an osteochondroma?

. Fibrocartilage
. Elastic cartilage
. Hyaline cartilage
. Articular cartilage
. Reticular cartilage

Correct Answer & Explanation

. Hyaline cartilage

Explanation

The cartilage cap of an osteochondroma is composed of hyaline cartilage, which is structurally and functionally similar to the growth plate cartilage. This cap is responsible for the continued growth of the osteochondroma. Fibrocartilage is found in menisci or intervertebral discs. Elastic cartilage is found in the ear. Articular cartilage lines joints. Reticular cartilage is not a recognized type.

Question 664

Topic: Bone Tumors

A 10-year-old child presents with a fixed bony mass near the ankle. MRI reveals an osteochondroma arising from the distal tibia, with a cartilage cap of 1 cm. There are no signs of compression or pain. What is the recommended follow-up interval?

. Every 3 months until skeletal maturity
. Annual clinical and radiographic follow-up until skeletal maturity
. No further follow-up is necessary
. MRI every 6 months
. Immediate surgical consultation

Correct Answer & Explanation

. Annual clinical and radiographic follow-up until skeletal maturity

Explanation

For an asymptomatic osteochondroma in a skeletally immature patient, observation with annual clinical and radiographic follow-up is generally recommended until skeletal maturity. This allows for monitoring of growth, development of symptoms, or angular deformities. More frequent imaging (MRI every 6 months) is usually reserved for suspicious lesions. No further follow-up is inappropriate. Immediate surgical consultation is not needed for asymptomatic lesions.

Question 665

Topic: Bone Tumors

Which of the following is considered a 'secondary' osteochondroma?

. A solitary osteochondroma occurring de novo
. An osteochondroma associated with Hereditary Multiple Exostoses (HME)
. An osteochondroma that has undergone malignant transformation into chondrosarcoma
. An osteochondroma arising after radiation therapy
. A subungual exostosis

Correct Answer & Explanation

. An osteochondroma that has undergone malignant transformation into chondrosarcoma

Explanation

The term 'secondary osteochondroma' is not a standard classification. However, an osteochondroma that has undergone malignant transformation to a chondrosarcoma is termed a 'secondary peripheral chondrosarcoma' (secondary, as it arose from a pre-existing lesion). The question implies this context. HME lesions are primary congenital lesions. Post-radiation lesions are 'radiation-induced exostoses'. Subungual exostosis is a specific type of osteochondroma. The most 'secondary' process among the options is the malignant change.

Question 666

Topic: Bone Tumors

A 13-year-old female presents with a painful osteochondroma of the distal femur that impinges on the vastus medialis muscle during knee flexion. Which of the following is the most appropriate treatment?

. Physical therapy to improve flexibility
. NSAIDs and activity modification
. Surgical excision of the osteochondroma
. Steroid injection into the lesion
. Observation until skeletal maturity

Correct Answer & Explanation

. Surgical excision of the osteochondroma

Explanation

When an osteochondroma causes mechanical symptoms such as muscle impingement and pain during movement, surgical excision is the definitive treatment. Conservative measures like physical therapy, NSAIDs, or steroid injections are unlikely to resolve mechanical impingement. Observation would allow symptoms to persist or worsen. Surgical excision relieves the mechanical obstruction.

Question 667

Topic: Bone Tumors

Which part of the body is LEAST commonly affected by osteochondromas?

. Distal femur
. Proximal tibia
. Proximal humerus
. Skull
. Pelvis

Correct Answer & Explanation

. Skull

Explanation

Osteochondromas most commonly occur in the metaphysis of long bones, particularly around the knee (distal femur, proximal tibia) and shoulder (proximal humerus). They can also occur in flat bones such as the pelvis, scapula, and ribs. They are exceedingly rare in the skull, as the skull bones develop from intramembranous ossification, not endochondral ossification from a growth plate.

Question 668

Topic: Bone Tumors

What term describes the characteristic appearance of an osteochondroma on plain radiographs where the cortex and medullary cavity of the exostosis are continuous with the parent bone?

. Ground glass appearance
. Onion skinning
. Continuity sign
. Codman's triangle
. Soap bubble appearance

Correct Answer & Explanation

. Continuity sign

Explanation

The 'continuity sign' or 'medullary continuity' refers to the pathognomonic radiographic feature of an osteochondroma where the cortex and medullary cavity of the exostosis are directly continuous with those of the underlying parent bone. Ground glass is fibrous dysplasia. Onion skinning is Ewing sarcoma. Codman's triangle is a periosteal reaction. Soap bubble appearance can be seen in ABC or giant cell tumor.

Question 669

Topic: Bone Tumors

A 17-year-old male with a history of HME presents with an osteochondroma causing impingement on the adjacent ulna, leading to forearm rotation limitation. Which surgical principle is paramount for preventing recurrence and effectively addressing the impingement?

. Curettage of the cartilage cap
. Complete excision of the osteochondroma including its cartilage cap and perichondrium
. Partial excision to preserve the growth plate
. Radiation therapy to shrink the lesion
. Internal fixation of the lesion

Correct Answer & Explanation

. Complete excision of the osteochondroma including its cartilage cap and perichondrium

Explanation

For effective treatment of a symptomatic osteochondroma and to minimize recurrence, complete surgical excision of the entire osteochondroma, including its cartilage cap and any associated perichondrium (especially if near a joint or growth plate), is crucial. Incomplete removal of the cartilage cap is a common cause of recurrence. Curettage alone is insufficient. Partial excision is prone to recurrence. Radiation and internal fixation are not indicated.

Question 670

Topic: Bone Tumors

Which of the following is a key distinguishing feature between an osteochondroma and a parosteal osteosarcoma on MRI?

. Signal intensity on T1-weighted images
. Presence of a cartilage cap
. Periosteal reaction patterns
. Continuity of the medullary bone with the parent cortex
. Presence of fatty marrow within the lesion

Correct Answer & Explanation

. Continuity of the medullary bone with the parent cortex

Explanation

While both can be surface lesions, the critical differentiating factor, especially evident on MRI, is the continuity of the medullary bone of the lesion with the parent bone in an osteochondroma. Parosteal osteosarcoma typically has a clear cleavage plane between the tumor and the underlying cortex, and there is no medullary continuity. A cartilage cap is unique to osteochondroma. Fatty marrow can be present in both, but its continuity is key. Periosteal reaction can be variable. Signal intensity alone is not definitive.

Question 671

Topic: Bone Tumors

When is an osteochondroma considered 'active' or 'growing'?

. When the patient reports any pain
. When the cartilage cap is visible on X-ray
. When the patient is skeletally immature and the lesion increases in size
. When it forms a bursa
. When it causes neurological symptoms

Correct Answer & Explanation

. When the patient is skeletally immature and the lesion increases in size

Explanation

An osteochondroma is considered 'active' or 'growing' when it increases in size in a skeletally immature patient, as its growth is linked to the adjacent physis. Once the physis fuses at skeletal maturity, the osteochondroma typically stops growing. Pain, visible cartilage cap (not visible on X-ray), bursa formation, or neurological symptoms are complications or features, not direct indicators of continued growth of the bone itself.

Question 672

Topic: Bone Tumors

A rare but serious complication of osteochondromas, particularly in the popliteal fossa, can be the formation of a pseudoaneurysm. What clinical finding would be most suggestive of this complication?

. Progressive foot drop
. Acute, severe pain with swelling and pulsation
. Chronic, dull aching pain with stiffness
. Skin discoloration with associated numbness
. Audible crepitus with movement

Correct Answer & Explanation

. Acute, severe pain with swelling and pulsation

Explanation

A pseudoaneurysm formation due to irritation or injury of an artery (e.g., popliteal artery in the popliteal fossa) by an osteochondroma presents as acute, severe pain, rapidly enlarging swelling, and a palpable pulsatile mass. This is a surgical emergency. Foot drop implies nerve compression. Chronic pain suggests bursitis or other mechanical issues. Skin discoloration and numbness are non-specific. Crepitus suggests bursitis or fracture.

Question 673

Topic: Bone Tumors

Which diagnostic challenge might arise when an osteochondroma is located near a joint with extensive bursal formation?

. Difficulty distinguishing it from an enchondroma
. Mimicking a soft tissue mass without a clear bony component on imaging
. Confusion with an osteoid osteoma due to similar pain patterns
. Misdiagnosis as a stress fracture
. Inability to perform MRI due to artifact

Correct Answer & Explanation

. Mimicking a soft tissue mass without a clear bony component on imaging

Explanation

An osteochondroma with extensive bursal formation can present as a soft, fluctuant, or cystic-appearing mass, which might obscure the underlying bony component clinically and sometimes on less detailed imaging. This can lead to the lesion being mistaken for a purely soft tissue mass or a cystic lesion without appreciating its underlying bony origin. Enchondromas are intramedullary. Osteoid osteoma pain is typically nocturnal. Stress fractures are different entities. MRI is generally well-tolerated.

Question 674

Topic: Bone Tumors

Which of the following chondrosarcoma variants is characterized histologically by a biphasic pattern of small, round undifferentiated cells and islands of well-differentiated hyaline cartilage?

. Conventional chondrosarcoma.
. Dedifferentiated chondrosarcoma.
. Mesenchymal chondrosarcoma.
. Clear cell chondrosarcoma.
. Juxtacortical chondrosarcoma.

Correct Answer & Explanation

. Mesenchymal chondrosarcoma.

Explanation

Mesenchymal chondrosarcoma is classically described by its biphasic histological pattern: a primitive, small round cell component resembling Ewing sarcoma or hemangiopericytoma, and distinct islands of hyaline cartilage. This unique histology contributes to its more aggressive behavior and responsiveness to chemotherapy, unlike conventional chondrosarcoma. Other variants do not share this specific biphasic morphology.

Question 675

Topic: Bone Tumors

Which of the following is considered the most common site for conventional chondrosarcoma?

. Small bones of the hands and feet.
. Distal femur and proximal tibia.
. Pelvis and proximal femur.
. Vertebrae.
. Ribs.

Correct Answer & Explanation

. Pelvis and proximal femur.

Explanation

The pelvis and proximal femur are the most common sites for conventional chondrosarcoma, accounting for a significant proportion of cases. While chondrosarcoma can occur in any bone, including small bones, vertebrae, ribs, and long bones, the large flat bones of the pelvis and proximal long bones are classic locations.

Question 676

Topic: Bone Tumors

What is a key difference in the clinical presentation of an enchondroma versus a low-grade chondrosarcoma in an adult?

. Enchondromas are typically painful, while chondrosarcomas are not.
. Low-grade chondrosarcomas are often asymptomatic, while enchondromas usually cause fractures.
. Enchondromas commonly present with pathological fractures; low-grade chondrosarcomas present with localized pain.
. Enchondromas are typically asymptomatic unless complicated by fracture, whereas new or increasing pain in an adult is a red flag for chondrosarcoma.
. Both are typically painful from onset.

Correct Answer & Explanation

. Enchondromas are typically asymptomatic unless complicated by fracture, whereas new or increasing pain in an adult is a red flag for chondrosarcoma.

Explanation

Enchondromas are typically asymptomatic incidental findings unless they cause a pathological fracture. In contrast, new onset or increasing dull, persistent pain in an adult with a cartilaginous lesion, especially in a central location, is a classic warning sign for malignant transformation to chondrosarcoma, even low-grade. While low-grade chondrosarcomas can be asymptomatic initially, pain is a much more common presentation than with enchondromas, which only become painful with complications.

Question 677

Topic: Bone Tumors
Which histological subtype of chondrosarcoma is known for its relatively indolent course, often affecting the epiphyses of long bones, and may be confused with chondroblastoma?
. Dedifferentiated chondrosarcoma.
. Mesenchymal chondrosarcoma.
. Conventional chondrosarcoma (Grade III).
. Clear cell chondrosarcoma.
. Juxtacortical chondrosarcoma.

Correct Answer & Explanation

. Clear cell chondrosarcoma.

Explanation

Clear cell chondrosarcoma is a rare, low-grade variant typically found in the epiphyses of long bones (e.g., proximal humerus, distal femur, proximal tibia) of young to middle-aged adults. Its histological features (clear cells, reactive bone formation, often epiphyseal location) can lead to misdiagnosis as chondroblastoma. It has a relatively indolent course compared to other malignant chondrosarcoma types, but still requires wide excision.

Question 678

Topic: Bone Tumors
What is the defining characteristic of a low-grade (Grade I) conventional chondrosarcoma on histological examination?
. High mitotic activity and extensive necrosis.
. Marked cellular pleomorphism and prominent spindle cell component.
. Mildly increased cellularity with plump nuclei, occasional binucleation, and permeation of marrow spaces.
. Sheets of small, round blue cells with interspersed cartilage islands.
. Epithelioid cells with clear cytoplasm in an epiphyseal location.

Correct Answer & Explanation

. Mildly increased cellularity with plump nuclei, occasional binucleation, and permeation of marrow spaces.

Explanation

Grade I conventional chondrosarcoma is characterized by mildly increased cellularity compared to enchondroma, with plump nuclei, occasional binucleation, and a hallmark feature is the permeation of marrow fat spaces by tumor cells. High mitotic activity, necrosis, and marked pleomorphism are features of higher grades (II and III). Small round blue cells and cartilage islands define mesenchymal chondrosarcoma. Epithelioid clear cells define clear cell chondrosarcoma.

Question 679

Topic: Bone Tumors

A 30-year-old patient has a suspected chondrosarcoma in the femoral shaft. Which imaging characteristic on MRI would be most concerning for a high-grade lesion rather than a low-grade one?

. Endosteal scalloping of the cortex.
. Lobulated growth pattern with internal septa.
. Well-defined sclerotic border.
. Cortical destruction and extraosseous extension.
. Punctate calcifications within the matrix.

Correct Answer & Explanation

. Cortical destruction and extraosseous extension.

Explanation

Cortical destruction and extraosseous extension into surrounding soft tissues are hallmark signs of an aggressive, higher-grade chondrosarcoma. Endosteal scalloping, lobulated growth pattern, and punctate calcifications can be seen in both low-grade chondrosarcomas and even some enchondromas, though more pronounced scalloping and lobulation suggest malignancy. A well-defined sclerotic border is usually a feature of a benign lesion or a very indolent process, not a high-grade chondrosarcoma.

Question 680

Topic: Bone Tumors

What is the typical age range for the presentation of conventional chondrosarcoma?

. Childhood (0-10 years).
. Adolescence (10-20 years).
. Young adults (20-40 years).
. Middle to older adulthood (40-70+ years).
. Any age, with no clear peak.

Correct Answer & Explanation

. Middle to older adulthood (40-70+ years).

Explanation

Conventional chondrosarcoma typically presents in middle to older adulthood, with a peak incidence in the 5th to 7th decades of life (40-70+ years). While it can occur in younger individuals, especially in the setting of syndromes like Ollier's or Maffucci's, it is rare in childhood and adolescence. Other variants like mesenchymal chondrosarcoma may affect younger populations.

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