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10. Pathology and Oncology MCQs

Practice Set 253 of 351

This practice set contains high-yield board review questions covering key concepts in 10. Pathology and Oncology. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 5041

Topic: 10. Pathology and Oncology

A 14-year-old presents with a rapidly growing lesion in the proximal femur. Biopsy reveals an Aneurysmal Bone Cyst. Due to the size and rapid growth, which of the following non-surgical adjuncts or primary treatments could be considered before or instead of extensive surgery?

. Long-term systemic antibiotics.
. External beam radiation therapy (EBRT) as a primary treatment.
. Intralesional sclerotherapy with agents like polidocanol or doxycycline.
. Systemic chemotherapy.
. Bisphosphonate infusions.

Correct Answer & Explanation

. Intralesional sclerotherapy with agents like polidocanol or doxycycline.

Explanation

Intralesional sclerotherapy, using agents such as polidocanol, doxycycline, or absolute alcohol, is an evolving non-surgical or minimally invasive treatment option for ABCs, particularly for large or inaccessible lesions, or when trying to avoid extensive surgery and associated risks. It works by causing endothelial damage and thrombosis, leading to fibrosis and regression of the cyst. Systemic antibiotics and chemotherapy are not indicated. EBRT is generally avoided in children due to radiation risks (malignant transformation, growth arrest) and reserved for highly recurrent or inaccessible lesions not responsive to other treatments. Bisphosphonates are not standard for ABC.

Question 5042

Topic: Bone Tumors

What is a potential risk of using phenol as an adjuvant after curettage for an Aneurysmal Bone Cyst, particularly in locations near neurovascular bundles?

. Increased risk of infection.
. Direct neurovascular damage if not carefully contained.
. Delayed bone healing due to excessive sclerosis.
. Reduced efficacy compared to simple curettage.
. Systemic allergic reaction.

Correct Answer & Explanation

. Direct neurovascular damage if not carefully contained.

Explanation

Phenol is a chemical cauterant used as an adjuvant. A significant risk of using phenol, especially in anatomical locations close to neurovascular bundles (e.g., popliteal fossa, brachial plexus), is direct neurovascular damage if the phenol is not carefully contained within the cyst cavity or if it extravasates. It causes chemical necrosis. Therefore, careful application and neutralization are crucial. It is highly effective when properly used and not associated with increased infection, reduced efficacy, or typically systemic allergic reaction.

Question 5043

Topic: 10. Pathology and Oncology

Which histological component, while present, is typically not the primary defining feature of an Aneurysmal Bone Cyst but often confuses it with a different lesion?

. Large blood-filled spaces.
. Fibrous septa.
. Hemosiderin-laden macrophages.
. Multinucleated giant cells.
. Reactive woven bone.

Correct Answer & Explanation

. Multinucleated giant cells.

Explanation

Multinucleated giant cells are a prominent feature of Aneurysmal Bone Cysts, but they are also the hallmark of Giant Cell Tumors (GCTs). Their presence often leads to confusion or misdiagnosis, especially if the characteristic large blood-filled spaces, fibrous septa, and reactive woven bone (without malignant osteoid) are not fully appreciated. The large blood-filled spaces are actually adefiningcharacteristic of ABC.

Question 5044

Topic: Bone Tumors

In the case of a recurrent Aneurysmal Bone Cyst in the distal femur of a 16-year-old, which treatment approach might offer the best local control but at the cost of higher morbidity?

. Repeat intralesional curettage with cryotherapy.
. Pre-operative embolization followed by repeat curettage.
. En bloc resection with reconstruction.
. Sclerotherapy with polidocanol.
. Low-dose palliative radiation therapy.

Correct Answer & Explanation

. En bloc resection with reconstruction.

Explanation

For a recurrent Aneurysmal Bone Cyst, particularly if locally aggressive or in a challenging location, en bloc resection offers the highest rate of local control compared to intralesional treatments. However, it comes at the cost of significant morbidity, requiring extensive bone and soft tissue removal and often complex reconstructive surgery (e.g., allograft, endoprosthesis). While other options are less morbid, they may have higher recurrence rates. Low-dose radiation is generally reserved for refractory cases in vital structures, not primary recurrence in the appendicular skeleton.

Question 5045

Topic: Bone Tumors

A 10-year-old male presents with a non-painful but growing lesion in the ilium. Imaging suggests an Aneurysmal Bone Cyst. Which imaging modality would be most useful to assess the full extent of the lesion, including potential soft tissue involvement and proximity to pelvic organs?

. Plain Radiographs
. Computed Tomography (CT)
. Magnetic Resonance Imaging (MRI)
. Bone Scintigraphy
. Ultrasound

Correct Answer & Explanation

. Magnetic Resonance Imaging (MRI)

Explanation

Magnetic Resonance Imaging (MRI) is superior for assessing the full extent of bone lesions, especially in complex anatomical regions like the pelvis. It provides excellent soft tissue contrast, allowing for clear delineation of the lesion's relationship to adjacent muscles, nerves, blood vessels, and pelvic organs, as well as detecting any extra-osseous soft tissue involvement. While CT shows bone detail, MRI is far better for soft tissue assessment. Plain radiographs are limited to bony contours, and bone scintigraphy shows metabolic activity but poor anatomical detail. Ultrasound has limited utility for deep bone lesions.

Question 5046

Topic: 10. Pathology and Oncology

What is a major concern when using radiation therapy to treat an Aneurysmal Bone Cyst in a child?

. Ineffectiveness of radiation therapy for ABCs.
. Risk of radiation-induced malignancy (sarcoma) and growth disturbance.
. Immediate pathological fracture due to radiation.
. Increased risk of infection at the radiation site.
. Rapid systemic toxicity from radiation exposure.

Correct Answer & Explanation

. Risk of radiation-induced malignancy (sarcoma) and growth disturbance.

Explanation

A major concern with using radiation therapy for Aneurysmal Bone Cysts in children is the significant risk of radiation-induced malignancy, particularly osteosarcoma, and potential growth disturbances (e.g., limb length discrepancy, angular deformity) if the growth plate is in the field of radiation. For these reasons, radiation therapy is generally reserved as a last resort for recurrent, aggressive, or surgically inaccessible lesions, especially in critical locations like the spine or pelvis, and only after other options have been exhausted.

Question 5047

Topic: Bone Tumors

Which condition is characterized by multiple, often cystic, lesions resembling Aneurysmal Bone Cysts, but with a more diffuse and sometimes familial pattern?

. McCune-Albright Syndrome
. Neurofibromatosis Type 1
. Familial Aneurysmal Bone Cyst
. Noonan Syndrome
. Multiple Hereditary Exostoses

Correct Answer & Explanation

. Familial Aneurysmal Bone Cyst

Explanation

While rare, there have been reports of multiple or 'familial' Aneurysmal Bone Cysts, sometimes associated with systemic conditions or primary tumors. However, a condition known as 'multiple aneurysmal bone cysts' (MABC) is recognized, sometimes associated with a systemic vasculopathy, which can present with multiple lesions in a diffuse pattern. This is distinct from other syndromes. McCune-Albright has fibrous dysplasia, NF1 has bone dysplasias, Noonan Syndrome has skeletal anomalies, and MHE has osteochondromas.

Question 5048

Topic: Bone Tumors

When considering the long-term follow-up of a child treated for an Aneurysmal Bone Cyst in a long bone, what imaging modality is usually sufficient for routine surveillance to detect recurrence after the initial healing phase?

. Serial MRI scans every 6 months.
. Yearly PET/CT scans.
. Regular plain radiographs of the affected bone.
. Ultrasound of the soft tissues around the site.
. Bone scintigraphy.

Correct Answer & Explanation

. Regular plain radiographs of the affected bone.

Explanation

After the initial healing phase and once stability is achieved, regular plain radiographs of the affected bone are usually sufficient for routine surveillance to detect local recurrence in a long bone. Changes in bony architecture, cortical thinning, or the reappearance of lytic areas would prompt further investigation with MRI. Serial MRI scans are often done initially but become less frequent once stable. PET/CT is not standard for routine ABC follow-up. Ultrasound and bone scintigraphy have limited roles in long-term recurrence detection in this context.

Question 5049

Topic: 10. Pathology and Oncology

A 10-year-old child presents with a painful, rapidly enlarging lesion in the metaphyseal region of the distal femur. X-rays show an expansile lytic lesion with a 'soap-bubble' appearance. MRI confirms fluid-fluid levels. A biopsy is performed, and the pathologist notes blood-filled spaces, fibrous septa, scattered giant cells, and reactive woven bone. Which of the following statements about the local recurrence rate after adequate surgical treatment of this lesion is most accurate?

. Local recurrence is extremely rare, less than 1%.
. Local recurrence rates are typically between 10-30% even with thorough treatment.
. Local recurrence only occurs if the lesion was previously fractured.
. Local recurrence is almost 100% within the first year.
. Local recurrence is higher in skeletally mature patients.

Correct Answer & Explanation

. Local recurrence rates are typically between 10-30% even with thorough treatment.

Explanation

Even with thorough surgical treatment, including curettage and adjuvant therapy, the local recurrence rate for Aneurysmal Bone Cysts is typically reported to be between 10% and 30%. This underscores the locally aggressive nature of the lesion and the importance of complete removal of viable tissue and close follow-up. It is not extremely rare, nor is it 100%. Recurrence is not solely tied to prior fracture, and it is generally higher in younger, skeletally immature patients due to the higher metabolic activity.

Question 5050

Topic: Bone Tumors

When evaluating an osteochondroma, what specific feature on an X-ray confirms its diagnosis and differentiates it from other surface lesions?

. A 'sunburst' periosteal reaction
. A lytic lesion with a sclerotic rim
. Continuity of the cortex and medullary bone of the lesion with the parent bone
. A purely cartilaginous mass
. Presence of internal calcifications

Correct Answer & Explanation

. Continuity of the cortex and medullary bone of the lesion with the parent bone

Explanation

The hallmark radiographic feature of an osteochondroma is the continuity of the cortical and medullary bone of the exostosis with that of the underlying parent bone. This is crucial for differentiation. 'Sunburst' reaction suggests osteosarcoma. Lytic lesions with sclerotic rims are seen in osteoid osteoma. A purely cartilaginous mass is not typical for an osteochondroma, which is osteocartilaginous. Internal calcifications can be seen in various cartilaginous lesions.

Question 5051

Topic: 10. Pathology and Oncology

A 40-year-old patient with a history of HME presents with a new, rapidly enlarging, painful mass in the pelvic region. What is the approximate risk of malignant transformation for a patient with HME?

. Less than 1%
. 1-2%
. 5-25%
. 50%
. Nearly 100%

Correct Answer & Explanation

. 5-25%

Explanation

The risk of malignant transformation in patients with Hereditary Multiple Exostoses (HME) is significantly higher than in solitary osteochondromas. Estimates range from 5% to 25%, depending on the study and diagnostic criteria. Solitary lesions have a risk of less than 1%. The clinical scenario strongly suggests malignant transformation, reinforcing the importance of knowing the increased risk in HME.

Question 5052

Topic: 10. Pathology and Oncology

Which of the following is NOT a typical complication of an osteochondroma?

. Fracture of the stalk
. Bursitis over the lesion
. Malignant transformation to chondrosarcoma
. Pathologic fracture of the adjacent parent bone
. Neurovascular compression

Correct Answer & Explanation

. Pathologic fracture of the adjacent parent bone

Explanation

Pathologic fracture of theadjacent parent bonedue to an osteochondroma is not a typical complication. The fracture typically occurs through the stalk of the osteochondroma itself. All other options (stalk fracture, bursitis, malignant transformation, neurovascular compression) are well-documented and common complications of osteochondromas.

Question 5053

Topic: Bone Tumors

An osteochondroma typically arises from which part of a long bone?

. Diaphysis
. Epiphysis
. Physis (growth plate)
. Articular cartilage
. Cortex, without medullary involvement

Correct Answer & Explanation

. Physis (growth plate)

Explanation

Osteochondromas are believed to arise from aberrant cartilage cells within the perichondrium or physis (growth plate) that escape the growth plate and continue to grow outward, forming an exostosis. They are metaphyseal lesions, meaning they originate near the physis and grow away from the joint. They are not diaphyseal, epiphyseal, or purely cortical without medullary involvement.

Question 5054

Topic: 10. Pathology and Oncology

A 14-year-old girl with a history of a sessile osteochondroma on her rib presents with gradually increasing shortness of breath and pleuritic chest pain. What is the most serious potential complication to consider in this scenario?

. Simple fracture of the rib
. Pneumothorax due to pleural irritation
. Malignant transformation to chondrosarcoma
. Intercostal nerve compression
. Costochondritis

Correct Answer & Explanation

. Pneumothorax due to pleural irritation

Explanation

While malignant transformation is a concern for any osteochondroma, a rib osteochondroma with symptoms of shortness of breath and pleuritic chest pain raises suspicion for pneumothorax, especially if the osteochondroma points inwards or is subject to repetitive trauma, irritating or perforating the pleura. This can be an acute and serious complication. Malignant transformation is a slower process. Nerve compression would cause radicular pain. Fracture is less likely to cause respiratory distress acutely. Costochondritis is inflammation, not directly related to the mass.

Question 5055

Topic: 10. Pathology and Oncology

Regarding the gross pathological features of an osteochondroma, which statement is most accurate?

. It is composed entirely of cortical bone.
. It is a soft, fleshy tumor with no bony component.
. It consists of a bony stalk or base covered by a hyaline cartilage cap.
. It is a purely cystic lesion.
. The cartilage cap is typically calcified throughout its thickness.

Correct Answer & Explanation

. It consists of a bony stalk or base covered by a hyaline cartilage cap.

Explanation

Grossly, an osteochondroma is characterized by a bony stalk or base that is continuous with the cortex and medullary cavity of the parent bone, and this entire structure is capped by hyaline cartilage. This cartilage cap is responsible for the growth of the osteochondroma. The cap is cartilaginous, not entirely calcified. It is not purely cortical, fleshy, or cystic.

Question 5056

Topic: 10. Pathology and Oncology

In the context of Hereditary Multiple Exostoses (HME), why is careful follow-up recommended even for asymptomatic lesions?

. To monitor for spontaneous regression of lesions.
. To detect early signs of secondary infection.
. To identify malignant transformation to chondrosarcoma.
. To prevent growth plate fusion.
. To manage chronic pain proactively.

Correct Answer & Explanation

. To identify malignant transformation to chondrosarcoma.

Explanation

For patients with HME, careful long-term follow-up is crucial primarily to monitor for signs of malignant transformation, which is a significant risk (5-25%) compared to solitary osteochondromas. Regular clinical examination for new pain or rapid growth, and imaging for increased cartilage cap thickness, are part of this surveillance. Spontaneous regression is rare, infection is uncommon, growth plate fusion is a consequence of the disease itself, and asymptomatic lesions do not require proactive pain management.

Question 5057

Topic: 10. Pathology and Oncology

A 28-year-old male presents with chronic deep venous thrombosis (DVT) in his right leg. Imaging reveals a large osteochondroma located in the popliteal fossa. What is the most likely mechanism for the DVT in this patient?

. Hypercoagulable state associated with bone tumors
. Venous stasis due to direct extrinsic compression of the popliteal vein
. Arterial injury leading to secondary venous thrombosis
. Inflammatory response around the osteochondroma
. Nerve compression causing vascular spasm

Correct Answer & Explanation

. Venous stasis due to direct extrinsic compression of the popliteal vein

Explanation

A large osteochondroma in the popliteal fossa can cause direct extrinsic compression of the popliteal vein, leading to venous stasis, which is a major predisposing factor for deep venous thrombosis (DVT). This is a well-recognized vascular complication of osteochondromas in this location. While a hypercoagulable state is a risk for DVT in general, it's not directly related to benign bone tumors like osteochondromas. Arterial injury is less common and would usually present differently. Inflammation or nerve compression are not primary mechanisms for DVT.

Question 5058

Topic: 10. Pathology and Oncology

Which surgical indication for an osteochondroma is generally considered non-controversial?

. Cosmetic deformity without symptoms
. Asymptomatic sessile lesion in the distal femur
. Presence of a cartilage cap measuring 1.5 cm in a 12-year-old
. Symptoms of nerve or vascular compression
. Prophylactic removal for all HME lesions

Correct Answer & Explanation

. Symptoms of nerve or vascular compression

Explanation

Surgical excision of an osteochondroma is generally indicated and non-controversial when there are symptoms of nerve or vascular compression, significant pain, functional limitation, or suspicion of malignant transformation. Cosmetic deformity alone or asymptomatic lesions are usually observed. A 1.5 cm cartilage cap in a 12-year-old is typically within benign limits and would be observed (malignancy criteria are usually >2cm in adults, and rare in children). Prophylactic removal of all HME lesions is impractical and unnecessary.

Question 5059

Topic: 10. Pathology and Oncology

A 5-year-old girl has an asymptomatic osteochondroma of the proximal fibula. What is the most appropriate management at this time?

. Immediate surgical excision
. Observation with regular clinical and radiographic follow-up
. Radiation therapy to prevent growth
. Systemic chemotherapy
. Administration of bisphosphonates

Correct Answer & Explanation

. Observation with regular clinical and radiographic follow-up

Explanation

Asymptomatic osteochondromas, especially in young children, are typically managed with observation and regular clinical/radiographic follow-up. Surgical excision is reserved for symptomatic lesions, those causing functional impairment, or suspicious for malignant transformation. Radiation, chemotherapy, and bisphosphonates are not indicated for asymptomatic benign osteochondromas.

Question 5060

Topic: Bone Tumors

What is the primary factor that dictates the growth of an osteochondroma?

. Blood supply to the bony stalk
. The activity of the overlying hyaline cartilage cap
. Hormonal influences during puberty
. Mechanical stress on the lesion
. Medullary cavity expansion

Correct Answer & Explanation

. The activity of the overlying hyaline cartilage cap

Explanation

The growth of an osteochondroma is dependent on the activity of its overlying hyaline cartilage cap, which functions similarly to a miniature physis. It is this cartilaginous cap that continues to proliferate and expand, leading to the outward growth of the bony exostosis. Once the growth plate fuses at skeletal maturity, the cartilage cap typically ossifies, and the osteochondroma stops growing. Blood supply, hormones, mechanical stress, or medullary expansion are not the primary drivers of growth.

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