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Bone Tumors MCQs

Practice Set 33 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 641

Topic: Bone Tumors

What is the role of preoperative selective arterial embolization in the management of large Aneurysmal Bone Cysts?

. To definitively cure the lesion without subsequent surgery.
. To confirm the diagnosis histopathologically.
. To reduce intraoperative blood loss and facilitate surgical resection.
. To promote bone healing and ossification within the cyst.
. To prevent pathological fractures during surgery.

Correct Answer & Explanation

. To reduce intraoperative blood loss and facilitate surgical resection.

Explanation

Preoperative selective arterial embolization is commonly used for large, highly vascular Aneurysmal Bone Cysts, especially in the spine or pelvis. Its primary role is to reduce intraoperative blood loss, making subsequent surgical curettage or resection safer and more manageable. While it can sometimes lead to cyst regression (and in some very select cases, may be used as primary treatment for truly inaccessible lesions), it is not typically considered definitive monotherapy for most surgically accessible ABCs and does not confirm diagnosis or prevent fracture during surgery itself.

Question 642

Topic: Bone Tumors

What is the characteristic appearance of the periosteum associated with an Aneurysmal Bone Cyst on plain radiographs?

. Solid periosteal reaction (Codman's triangle).
. Absent periosteal reaction.
. Thin, 'blown-out' or 'eggshell' periosteal shell.
. Lamellated periosteal reaction (onion skin).
. Sunburst periosteal reaction.

Correct Answer & Explanation

. Thin, 'blown-out' or 'eggshell' periosteal shell.

Explanation

Aneurysmal Bone Cysts are typically expansile, causing thinning and ballooning of the overlying cortex and periosteum, often described as a 'blown-out' or 'eggshell' appearance. This indicates a relatively slow but continuous expansion that allows the periosteum to form a reactive shell. Solid periosteal reaction (Codman's triangle) and sunburst appearance are often associated with aggressive or malignant lesions like osteosarcoma. Lamellated (onion skin) is seen with Ewing sarcoma or osteomyelitis. Absent periosteal reaction is unlikely in a rapidly expanding lesion.

Question 643

Topic: Bone Tumors

A 20-year-old male with a history of an Aneurysmal Bone Cyst in the proximal tibia, treated with curettage and cryotherapy 5 years ago, now presents with recurrence. The new lesion is smaller but symptomatic. What is the most appropriate next step in management?

. Initiate systemic chemotherapy.
. Perform a second curettage with adjuvant, potentially more aggressive.
. Observe with serial imaging, as recurrence typically resolves spontaneously.
. Administer palliative radiation therapy.
. Amputation of the affected limb.

Correct Answer & Explanation

. Perform a second curettage with adjuvant, potentially more aggressive.

Explanation

For a recurrent Aneurysmal Bone Cyst, especially if symptomatic, a second surgical intervention (repeat curettage) with adjuvant therapy is often the most appropriate next step. The adjuvant may be more aggressively applied or a different one used. While embolization could be an option depending on the lesion, systemic chemotherapy is not indicated, observation is inappropriate for a symptomatic recurrence, palliative radiation is reserved for very specific refractory or inaccessible cases, and amputation is a last resort rarely necessary for ABCs.

Question 644

Topic: Bone Tumors

In evaluating an Aneurysmal Bone Cyst, which finding on CT scan provides unique information compared to plain radiographs?

. Overall lesion size and location.
. Presence of fluid-fluid levels.
. Detailed assessment of cortical destruction and integrity.
. Identification of soft tissue extension.
. Differentiation of solid versus cystic components.

Correct Answer & Explanation

. Detailed assessment of cortical destruction and integrity.

Explanation

While MRI is superior for fluid-fluid levels and soft tissue extension, and plain radiographs show overall size/location, CT excels in providing a detailed assessment of cortical destruction, integrity, and any subtle bone matrix. It is particularly useful for surgical planning to understand the extent of cortical thinning and potential breaches. Differentiation of solid versus cystic components is best done with MRI.

Question 645

Topic: Bone Tumors

A 16-year-old competitive athlete with an Aneurysmal Bone Cyst in the distal tibia is considering surgery. What is a key consideration for returning to high-impact sports after successful surgical treatment?

. Immediate return to sports upon wound healing.
. A period of activity restriction to allow for bone remodeling and consolidation.
. Lifelong avoidance of high-impact activities.
. Only possible if prosthetic replacement was performed.
. No specific restrictions are needed as long as pain-free.

Correct Answer & Explanation

. A period of activity restriction to allow for bone remodeling and consolidation.

Explanation

After surgical treatment of an Aneurysmal Bone Cyst, especially in a weight-bearing bone, a period of activity restriction is crucial to allow for sufficient bone remodeling and consolidation within the defect. The bone defect from curettage, even with bone grafting, takes time to regain full structural integrity. Premature return to high-impact activities carries a significant risk of pathological fracture. Lifelong avoidance is usually unnecessary, and prosthetic replacement is rarely performed for ABCs.

Question 646

Topic: Bone Tumors

Which of the following describes the most common anatomical location of Aneurysmal Bone Cysts?

. Diaphysis of long bones.
. Epiphysis of long bones.
. Metaphysis of long bones and posterior elements of vertebrae.
. Small bones of the hands and feet.
. Skull and facial bones.

Correct Answer & Explanation

. Metaphysis of long bones and posterior elements of vertebrae.

Explanation

Aneurysmal Bone Cysts most commonly occur in the metaphysis of long bones (e.g., femur, tibia, humerus) and the posterior elements of the vertebrae. They can also occur in flat bones (e.g., pelvis, scapula) and, less frequently, in the small bones of the hands and feet or the skull. Epiphyseal involvement, though possible, is less common than metaphyseal involvement. Diaphyseal location is also less common.

Question 647

Topic: Bone Tumors

A patient is undergoing treatment for an Aneurysmal Bone Cyst in a weight-bearing bone. Which adjuvant therapy, when used with curettage, is known to be associated with potential increased risk of pathological fracture, especially if poorly controlled or excessively applied?

. High-speed burr
. Liquid nitrogen cryotherapy
. Phenol
. Argon beam coagulation
. Bone wax

Correct Answer & Explanation

. Liquid nitrogen cryotherapy

Explanation

Liquid nitrogen cryotherapy, while effective in destroying residual cells, can cause extensive bone necrosis beyond the immediate target area if not carefully controlled. This can temporarily weaken the bone significantly, increasing the risk of pathological fracture, especially in weight-bearing bones, during the healing and remodeling phase. Phenol and argon beam coagulation have similar risks but are typically more localized. High-speed burr removes bone but doesn't cause widespread necrosis. Bone wax is a hemostatic agent.

Question 648

Topic: Bone Tumors

Which of the following management strategies is typically NOT considered for an Aneurysmal Bone Cyst in a young child if the lesion is small, asymptomatic, and not involving critical structures?

. Surgical curettage and bone grafting.
. Sclerotherapy.
. Observation with serial imaging.
. Selective arterial embolization.
. Systemic bisphosphonate therapy.

Correct Answer & Explanation

. Observation with serial imaging.

Explanation

For small, asymptomatic Aneurysmal Bone Cysts that do not involve critical structures (e.g., physis, major neurovascular bundles), a period of observation with serial imaging may be considered. This cautious approach acknowledges the potential for spontaneous regression (though rare) and avoids unnecessary intervention in a young child. Surgical curettage, sclerotherapy, and embolization are all active treatment modalities. Systemic bisphosphonate therapy is not a standard treatment for ABCs.

Question 649

Topic: Bone Tumors

Which characteristic of Aneurysmal Bone Cysts helps distinguish them from simple (unicameral) bone cysts on X-ray?

. Lack of septations.
. Central metaphyseal location.
. Eccentric location and expansile, 'blown-out' appearance.
. Presence of a fallen fragment sign.
. Thick, sclerotic wall.

Correct Answer & Explanation

. Eccentric location and expansile, 'blown-out' appearance.

Explanation

Aneurysmal Bone Cysts are typically eccentric, meaning they are located off-center within the bone, and display an expansile, 'blown-out' or 'soap bubble' appearance due to their rapid growth and cortical thinning. Simple bone cysts (UBCs) are typically centrally located in the metaphysis and rarely show significant cortical expansion. UBCs can have a 'fallen fragment sign' (a piece of fractured cortex within the fluid), which is not typical for ABCs. ABCs are septated, not lacking septations, and have a thin, not thick, sclerotic wall.

Question 650

Topic: Bone Tumors

When evaluating an Aneurysmal Bone Cyst in the sacrum, what additional consideration should be given to surgical approach and potential complications?

. The sacrum is a non-weight-bearing bone, simplifying recovery.
. High risk of bladder, bowel, and neurological injury due to proximity of sacral nerves.
. The lesion is typically easily accessible via a posterior approach.
. Sacral ABCs have a higher rate of spontaneous regression.
. Radiation therapy is the preferred first-line treatment for sacral ABCs.

Correct Answer & Explanation

. High risk of bladder, bowel, and neurological injury due to proximity of sacral nerves.

Explanation

Aneurysmal Bone Cysts in the sacrum pose significant surgical challenges due to the proximity of critical neurovascular structures (sacral nerve roots, rectum, bladder). Surgical approaches are complex, and there is a high risk of bladder, bowel, and neurological injury. Therefore, multidisciplinary planning and often embolization are essential. The sacrum is a weight-bearing bone. Spontaneous regression is rare, and radiation therapy is typically a last resort due to risks in children.

Question 651

Topic: Bone Tumors

Which of the following describes the typical histological appearance of the blood-filled spaces in an Aneurysmal Bone Cyst?

. Lined by a single layer of flattened endothelial cells.
. Completely devoid of any cellular lining.
. Lined by atypical, pleomorphic endothelial cells.
. Lined by stratified squamous epithelium.
. Lined by mature osteocytes.

Correct Answer & Explanation

. Completely devoid of any cellular lining.

Explanation

The blood-filled spaces within an Aneurysmal Bone Cyst are typicallynotlined by a true endothelial layer or are only focally lined. They are rather cavernous spaces within a fibrous stroma. Option 'Lined by a single layer of flattened endothelial cells' would be typical of a true blood vessel or vascular malformation but not the characteristic feature of ABC's pathological spaces. This absence or sparse endothelial lining is an important histological detail distinguishing it from other vascular lesions. However, out of the given options, if forced to choose the closest, sometimes an incomplete, non-atypical lining can be seen. But the critical point is that they are not true vascular malformations with a complete, mature endothelial lining. Let me re-evaluate the options. The blood-filled spaces arenottypically lined by true endothelium, which distinguishes them from true vascular malformations. This is a subtle but important point in pathology. If the spaces were completely devoid of any cellular lining, it would be different. They are essentially cystic cavities. Many sources describe them as 'lacking an endothelial lining' or having 'a sparse, incomplete lining'. Therefore, 'Completely devoid of any cellular lining' is a plausible interpretation of the characteristic lack oftrueendothelial lining of a blood vessel. Let me check standard pathology texts. Standard description: 'Blood-filled spaces of varying size, separated by fibrous septa. The spaces lack an endothelial lining.' So, 'Completely devoid of any cellular lining' is more accurate for thecharacteristicappearance than 'Lined by a single layer of flattened endothelial cells', which suggests true vascular channels. However, if there are some normal vessels, they would be endothelialized. The question asks for thetypicalappearance of theblood-filled spacesof an ABC. These spaces are often described as 'lacking a true endothelial lining'. So, 'Completely devoid of any cellular lining' is most representative of the lack of proper vessel lining. Re-reading my choice for 'ans', I put 0. Let's correct it based on the typical absence of true endothelial lining. The spaces are irregular and often communicate. The fibrous septa contain the characteristic cellular elements (fibroblasts, giant cells). The spaces themselves are often described as not having a true endothelial lining.

Question 652

Topic: Bone Tumors

A 5-year-old child presents with an Aneurysmal Bone Cyst in the proximal tibia, actively growing and causing pain. Embolization is being considered. What is the primary goal of pre-operative selective arterial embolization for a large ABC?

. To definitively cure the lesion without subsequent surgery.
. To confirm the diagnosis histopathologically.
. To reduce intraoperative blood loss and facilitate surgical resection.
. To promote bone healing and ossification within the cyst.
. To prevent pathological fractures during surgery.

Correct Answer & Explanation

. To reduce intraoperative blood loss and facilitate surgical resection.

Explanation

Pre-operative selective arterial embolization for a large Aneurysmal Bone Cyst primarily aims to reduce the vascularity of the lesion. This significantly decreases intraoperative blood loss during subsequent surgical procedures (like curettage and bone grafting), making the surgery safer and easier to perform. While embolization can sometimes lead to lesion regression, it is rarely considered definitive monotherapy for surgically accessible ABCs and does not confirm the diagnosis or prevent pathological fractures during surgery.

Question 653

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 654

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 655

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 656

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 657

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 658

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 659

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 660

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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