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10. Pathology and Oncology MCQs

Practice Set 252 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 5021

Topic: 10. Pathology and Oncology

The presence of which histological component, within the fibrous septa of an ABC, can sometimes lead to misdiagnosis as a Giant Cell Tumor if not interpreted in the full context of the lesion?

. Osteoid formation
. Cartilage islands
. Multinucleated giant cells
. Necrotic bone
. Fibrocartilage

Correct Answer & Explanation

. Multinucleated giant cells

Explanation

The presence of numerous multinucleated giant cells within the fibrous septa of an Aneurysmal Bone Cyst can sometimes lead to misdiagnosis as a Giant Cell Tumor (GCT), especially if the pathologist only samples a small portion of the lesion or focuses solely on these cells. However, GCTs typically have a more uniform distribution of giant cells within a neoplastic stromal cell population and lack the characteristic large blood-filled cystic spaces and reactive woven bone found in ABCs. Osteoid formation, cartilage islands, and necrotic bone are not primary features that cause this specific misdiagnosis.

Question 5022

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 5023

Topic: 10. Pathology and Oncology

Which factor is most strongly correlated with an increased risk of local recurrence after surgical treatment of an Aneurysmal Bone Cyst?

. Patient age over 18 years.
. Location in a non-weight-bearing bone.
. Incomplete intralesional curettage.
. Use of bone graft substitute instead of autograft.
. Preoperative embolization.

Correct Answer & Explanation

. Incomplete intralesional curettage.

Explanation

The most significant factor correlated with an increased risk of local recurrence after surgical treatment of an Aneurysmal Bone Cyst is incomplete intralesional curettage. Any residual viable cells in the cyst wall can lead to recurrence. This is why adjuvant therapies are so important. Patient age, specific bone graft type, and preoperative embolization (which aims to reduce blood loss, not necessarily eliminate recurrence) are less directly correlated with recurrence compared to the completeness of tumor removal.

Question 5024

Topic: 10. Pathology and Oncology

What is the typical presentation of pain associated with an Aneurysmal Bone Cyst?

. No pain, only swelling.
. Dull, persistent ache, often worse with activity and relieved by rest.
. Sharp, shooting pain radiating down the limb.
. Severe, throbbing pain, particularly worse at night.
. Intermittent pain only after trauma.

Correct Answer & Explanation

. Dull, persistent ache, often worse with activity and relieved by rest.

Explanation

The pain associated with an Aneurysmal Bone Cyst is typically a dull, persistent ache that may worsen with activity and be somewhat relieved by rest. It is usually not as severe or sharp as inflammatory pain or neuropathic pain. Swelling and tenderness are also common. While night pain can occur with bone lesions, it's more characteristic of malignant tumors. Pain only after trauma could suggest a pathological fracture rather than the typical pain from the expanding lesion itself.

Question 5025

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 5026

Topic: 10. Pathology and Oncology

A 10-year-old child has an Aneurysmal Bone Cyst in the proximal tibia. Post-curettage, the bone defect is large. Which material is commonly used to fill the bone defect to provide structural support and facilitate healing?

. Methyl methacrylate cement
. Silicone implant
. Autologous bone graft or bone graft substitutes
. Polyethylene terephthalate (Dacron)
. Polymethyl methacrylate (PMMA) beads

Correct Answer & Explanation

. Autologous bone graft or bone graft substitutes

Explanation

After thorough curettage of an Aneurysmal Bone Cyst, the resulting bone defect is typically filled with either autologous bone graft (from the iliac crest, for example) or various bone graft substitutes (e.g., allograft, calcium phosphate cements, synthetic bone matrices). These materials provide structural support, promote osteoconduction and sometimes osteoinduction, facilitating eventual bone healing and remodeling. Methyl methacrylate cement is usually used for structural support in aggressive benign or malignant tumors but is not ideal for growing children due to heat generation and lack of incorporation. Silicone, Dacron, and PMMA beads are not used for filling bone defects in this context.

Question 5027

Topic: 10. Pathology and Oncology

What is the primary role of a high-speed burr in the surgical treatment of Aneurysmal Bone Cysts?

. To create a smooth surface for bone grafting.
. To remove the soft tissue component of the cyst.
. To meticulously remove the inner lining and sclerotic rim of the cyst cavity.
. To perform an osteotomy for limb shortening.
. To apply adjuvant heat therapy.

Correct Answer & Explanation

. To meticulously remove the inner lining and sclerotic rim of the cyst cavity.

Explanation

A high-speed burr is a valuable tool in the surgical treatment of Aneurysmal Bone Cysts. Its primary role is to meticulously remove the entire inner lining of the cyst cavity and any sclerotic rim, ensuring complete removal of potentially viable tumor cells, especially after initial gross curettage. This reduces the risk of local recurrence. It is not primarily for smoothing surfaces, removing soft tissue (though some soft tissue is removed), osteotomy, or heat therapy.

Question 5028

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 5029

Topic: 10. Pathology and Oncology

Regarding the molecular pathology of primary Aneurysmal Bone Cysts, the USP6 gene rearrangement is thought to result in:

. Loss of function of a tumor suppressor gene.
. Overexpression of a proto-oncogene that promotes cell proliferation and osteoclastogenesis.
. Disruption of a gene involved in cartilage formation.
. Production of abnormal collagen leading to bone fragility.
. Activation of a gene responsible for vascular smooth muscle contraction.

Correct Answer & Explanation

. Overexpression of a proto-oncogene that promotes cell proliferation and osteoclastogenesis.

Explanation

The USP6 (ubiquitin specific peptidase 6) gene rearrangement, frequently seen in primary ABCs, leads to the overexpression of USP6. This overexpression is thought to promote cell proliferation of the stromal cells and enhance osteoclastogenesis (bone resorption) through various mechanisms, including upregulation of matrix metalloproteinases and inflammatory mediators. Therefore, it acts more like an activated proto-oncogene or a gene that drives the aggressive, lytic behavior rather than a loss of tumor suppressor function or disruption of cartilage formation.

Question 5030

Topic: 10. Pathology and Oncology

What is a potential serious long-term complication of treating an Aneurysmal Bone Cyst in the proximal femur of a young child, especially if extensive curettage and grafting are performed?

. Heterotopic ossification around the hip joint.
. Development of avascular necrosis of the femoral head.
. Increased risk of deep vein thrombosis.
. Malignant transformation to osteosarcoma.
. Neuropathy of the femoral nerve.

Correct Answer & Explanation

. Development of avascular necrosis of the femoral head.

Explanation

Treating an Aneurysmal Bone Cyst in the proximal femur of a young child, especially with extensive procedures, carries a risk of complications. Avascular necrosis (AVN) of the femoral head is a serious potential long-term complication if the blood supply to the epiphysis is compromised during surgery or due to the lesion's proximity. While other complications are possible, AVN is a specific concern in this anatomical area due to the critical vascularity of the femoral head in children. Malignant transformation is exceedingly rare.

Question 5031

Topic: 10. Pathology and Oncology

The rapid clinical growth and expansion of an Aneurysmal Bone Cyst is primarily due to:

. Rapid proliferation of malignant cells.
. Accumulation of pus within the cyst.
. Progressive hemorrhage and blood pooling within distended vascular spaces.
. Deposition of new bone by osteoblasts.
. Inflammatory edema and fluid accumulation.

Correct Answer & Explanation

. Progressive hemorrhage and blood pooling within distended vascular spaces.

Explanation

The rapid growth and expansile nature of Aneurysmal Bone Cysts are primarily attributed to progressive hemorrhage and the accumulation of blood (with varying degrees of clotting and lysis) within distended, non-endothelialized vascular spaces. This internal pressure, combined with osteoclast-mediated bone resorption by the stromal cells, leads to rapid bone destruction and expansion. It is not due to malignant cell proliferation or pus accumulation.

Question 5032

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 5033

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 5034

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 5035

Topic: 10. Pathology and Oncology

Which statement regarding the prognosis and follow-up of surgically treated Aneurysmal Bone Cysts is most accurate?

. Recurrence is rare, so long-term follow-up is not necessary.
. Regular clinical and radiographic follow-up is crucial for detecting recurrence, typically for 2-3 years post-surgery.
. Malignant transformation is a common late complication, requiring lifelong surveillance.
. Patients require prophylactic bisphosphonate therapy to prevent recurrence.
. Recurrence only occurs in the first 6 months post-surgery.

Correct Answer & Explanation

. Regular clinical and radiographic follow-up is crucial for detecting recurrence, typically for 2-3 years post-surgery.

Explanation

Regular clinical and radiographic follow-up is crucial for detecting local recurrence after surgical treatment of Aneurysmal Bone Cysts. Most recurrences occur within the first 2-3 years post-surgery, though some may appear later. Therefore, surveillance is typically recommended for this period. Recurrence is not rare. Malignant transformation is exceedingly rare. Prophylactic bisphosphonate therapy is not a standard treatment to prevent recurrence. Recurrence can occur beyond 6 months.

Question 5036

Topic: 10. Pathology and Oncology

What is the typical age range for occurrence of a Giant Cell Tumor (GCT) of bone, which is often considered in the differential diagnosis of an ABC in older adolescents or young adults?

. 0-5 years
. 5-10 years
. 10-20 years
. 20-40 years
. Over 60 years

Correct Answer & Explanation

. 20-40 years

Explanation

Giant Cell Tumors (GCTs) of bone typically occur in skeletally mature individuals, most commonly in the 20-40 year age range. This contrasts with Aneurysmal Bone Cysts, which are predominantly seen in children and adolescents (5-20 years). This age difference, along with their epiphyseal location, helps in distinguishing GCTs from ABCs, although secondary ABCs can occur within GCTs.

Question 5037

Topic: 10. Pathology and Oncology

When an Aneurysmal Bone Cyst is successfully treated, what is the expected outcome on follow-up radiographs?

. Complete disappearance of the lesion and normal bone architecture.
. Persistent lytic defect with no signs of healing.
. Sclerotic remodeling and gradual infilling of the defect with new bone.
. Progressive cortical thinning and expansion.
. Malignant transformation of the treated site.

Correct Answer & Explanation

. Sclerotic remodeling and gradual infilling of the defect with new bone.

Explanation

Following successful treatment of an Aneurysmal Bone Cyst, follow-up radiographs typically show sclerotic remodeling of the cyst walls and gradual infilling of the defect with new bone. The bone defect progressively ossifies and integrates into the surrounding healthy bone, though complete return to normal bone architecture may take years or may not fully occur. Persistent lytic defect or progressive expansion would suggest recurrence or inadequate treatment. Malignant transformation is exceedingly rare.

Question 5038

Topic: 10. Pathology and Oncology

In the differential diagnosis of a spinal Aneurysmal Bone Cyst causing neurological symptoms, which malignant tumor must always be considered due to its similar lytic, expansile nature?

. Multiple Myeloma
. Chondrosarcoma
. Ewing Sarcoma
. Metastatic Carcinoma
. Chordoma

Correct Answer & Explanation

. Chordoma

Explanation

Chordoma is a malignant tumor that commonly affects the axial skeleton, particularly the sacrum and skull base, but can also involve vertebral bodies. It presents as a lytic, expansile lesion and can cause neurological symptoms. Given its location and aggressive nature, it is a critical differential for an ABC in the spine. Multiple myeloma and metastatic carcinoma affect older adults. Chondrosarcoma and Ewing sarcoma, while malignant, typically have different radiological patterns and are less commonly considered direct mimics of an ABC compared to Chordoma in the spine.

Question 5039

Topic: 10. Pathology and Oncology

What is the typical radiographic appearance of the cortex surrounding an Aneurysmal Bone Cyst?

. Thickened and sclerotic.
. Completely eroded with no visible cortex.
. Thin and expanded ('blown-out').
. Laminated ('onion-skin') periosteal reaction.
. Dense cortical bone with intramedullary lucency.

Correct Answer & Explanation

. Thin and expanded ('blown-out').

Explanation

Aneurysmal Bone Cysts are characterized by their expansile growth, which leads to thinning and expansion of the cortical bone, often described as a 'blown-out' or 'eggshell' appearance. This contrasts with thick, sclerotic cortex (seen in some benign lesions or chronic osteomyelitis), laminated periosteal reaction (Ewing sarcoma), or complete erosion (highly aggressive malignancy). Dense cortical bone with intramedullary lucency is not typical for ABC.

Question 5040

Topic: 10. Pathology and Oncology

Which of the following describes a 'primary' Aneurysmal Bone Cyst?

. A lesion that developed secondary to trauma.
. A lesion found incidentally in an asymptomatic patient.
. A lesion that arises de novo without an identifiable pre-existing bone lesion.
. A lesion that recurs after previous treatment.
. A lesion that has undergone malignant transformation.

Correct Answer & Explanation

. A lesion that arises de novo without an identifiable pre-existing bone lesion.

Explanation

A primary Aneurysmal Bone Cyst is one that arises de novo, meaning it is not associated with or developing within another pre-existing bone lesion. In contrast, a secondary ABC develops within another lesion (e.g., fibrous dysplasia, GCT, chondroblastoma). While trauma can sometimes be a precipitating factor for symptoms, it doesn't define primary vs. secondary. Asymptomatic presentation is possible but not a definition. Recurrence and malignant transformation are complications, not definitions of primary ABC.

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