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10. Pathology and Oncology MCQs

Practice Set 4 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 61

Topic: 10. Pathology and Oncology

A 58-year-old female with metastatic breast cancer to the thoracic spine presents with confusion, abdominal pain, and polyuria. Laboratory tests show a serum calcium of 13.5 mg/dL. What is the primary mediator of this paraneoplastic syndrome?

. Parathyroid hormone (PTH)
. 1,25-dihydroxyvitamin D
. Parathyroid hormone-related protein (PTHrP)
. Interleukin-6 (IL-6)
. Tumor necrosis factor-alpha (TNF-alpha)

Correct Answer & Explanation

. Parathyroid hormone-related protein (PTHrP)

Explanation

Hypercalcemia of malignancy in solid tumors (like breast and lung cancer) is most commonly mediated by the secretion of parathyroid hormone-related protein (PTHrP). PTHrP mimics PTH, leading to increased bone resorption and renal calcium reabsorption.

Question 62

Topic: 10. Pathology and Oncology

A 45-year-old male presents with back pain and B symptoms. MRI of the lumbar spine shows extensive marrow replacement of L3 with a large, bulky paraspinal soft tissue mass, but minimal cortical bone destruction. What is the most likely diagnosis?

. Osteosarcoma
. Primary lymphoma of bone
. Metastatic prostate cancer
. Hemangioma
. Chondrosarcoma

Correct Answer & Explanation

. Primary lymphoma of bone

Explanation

Primary lymphoma of bone characteristically presents with a large soft-tissue mass out of proportion to the degree of cortical bone destruction. It permeates the marrow space through Haversian canals without extensively destroying the cortex.

Question 63

Topic: Bone Tumors

A 16-year-old male presents with a dull ache in his posterior neck. Radiographs show a 2.5 cm radiolucent lesion with a sclerotic rim in the C4 lamina. Histology shows interlacing woven bone trabeculae lined by a single layer of plump osteoblasts. What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Osteosarcoma
. Giant cell tumor

Correct Answer & Explanation

. Osteoblastoma

Explanation

The clinical presentation, size (>2 cm), location in the posterior elements of the spine, and histology are characteristic of an osteoblastoma. Osteoid osteomas are histologically identical but are typically less than 1.5 to 2 cm in diameter.

Question 64

Topic: 10. Pathology and Oncology

Which of the following is a key clinical differentiating factor between an osteoid osteoma and an osteoblastoma?

. Osteoblastomas predominantly occur in the diaphysis of long bones.
. Osteoid osteomas frequently cause progressive neurologic deficits.
. Pain from osteoblastoma is typically less responsive to NSAIDs.
. Osteoblastomas exhibit a characteristic dense central calcification on radiographs.
. Osteoid osteomas have a high rate of malignant transformation.

Correct Answer & Explanation

. Pain from osteoblastoma is typically less responsive to NSAIDs.

Explanation

Unlike osteoid osteomas, the pain associated with osteoblastoma is usually a dull ache that is not classically relieved by NSAIDs. Osteoblastomas also tend to be larger, occur more frequently in the spine, and are more likely to cause neurologic deficits.

Question 65

Topic: 10. Pathology and Oncology

A secondary aneurysmal bone cyst (ABC) is most commonly associated with which of the following underlying benign bone tumors?

. Giant cell tumor
. Enchondroma
. Fibrous dysplasia
. Non-ossifying fibroma
. Osteochondroma

Correct Answer & Explanation

. Giant cell tumor

Explanation

Approximately 30% of aneurysmal bone cysts are secondary lesions. The most common underlying precursor lesions are giant cell tumors, osteoblastomas, and chondroblastomas.

Question 66

Topic: 10. Pathology and Oncology

A 9-year-old boy presents with back pain. Radiographs reveal a completely collapsed vertebral body (vertebra plana) at T8 with preserved adjacent disc spaces. Laboratory tests are normal. What is the most likely diagnosis?

. Osteomyelitis
. Eosinophilic granuloma
. Ewing sarcoma
. Leukemia
. Osteoblastoma

Correct Answer & Explanation

. Eosinophilic granuloma

Explanation

Vertebra plana (a uniformly collapsed vertebral body) in a child is a classic radiographic hallmark of eosinophilic granuloma (Langerhans cell histiocytosis). The intervertebral disc spaces are characteristically preserved.

Question 67

Topic: Bone Tumors

Radiofrequency ablation (RFA) is considered the treatment of choice for most osteoid osteomas. What is the generally accepted minimum safe distance from the spinal cord or nerve roots to prevent thermal injury during RFA?

. 2 mm
. 5 mm
. 10 mm
. 15 mm
. 20 mm

Correct Answer & Explanation

. 10 mm

Explanation

To safely perform RFA for spinal osteoid osteomas without damaging neural elements, the lesion should generally be at least 10 mm away from the spinal cord and nerve roots. Closer proximity significantly increases the risk of thermal neuropraxia or permanent damage.

Question 68

Topic: 10. Pathology and Oncology

Which of the following histologic features is pathognomonic for a chordoma?

. Physaliferous cells
. Antoni A and B areas
. Homer-Wright rosettes
. Weibel-Palade bodies
. Langerhans giant cells

Correct Answer & Explanation

. Physaliferous cells

Explanation

Chordomas are malignant tumors arising from notochordal remnants, most commonly found in the sacrum and clivus. They are histologically characterized by physaliferous cells, which are large cells with vacuolated, bubbly cytoplasm.

Question 69

Topic: 10. Pathology and Oncology

A 65-year-old man with known Paget's disease presents with new, severe, unrelenting thigh pain. Radiographs show a destructive, permeative lesion in the femoral diaphysis. What is the most likely diagnosis?

. Pathologic fracture from Paget's disease
. Metastatic prostate cancer
. Chondrosarcoma
. Multiple myeloma
. Secondary osteosarcoma

Correct Answer & Explanation

. Secondary osteosarcoma

Explanation

New-onset severe pain or swelling in a bone affected by Paget's disease should raise high suspicion for malignant transformation. Secondary osteosarcoma is the most common and carries a very poor prognosis.

Question 70

Topic: Bone Tumors

What is the primary pathophysiologic mechanism of pain generated by an osteoid osteoma?

. Mechanical instability of the cortex
. High levels of Prostaglandin E2 produced by the nidus
. Compression of adjacent peripheral nerves
. Release of inflammatory cytokines from local hemorrhage
. Rapid periosteal expansion

Correct Answer & Explanation

. High levels of Prostaglandin E2 produced by the nidus

Explanation

The nidus of an osteoid osteoma produces high levels of Prostaglandin E2 (PGE2), which causes severe, deep, aching pain. This is the physiologic basis for why NSAIDs and aspirin are highly effective at relieving the pain.

Question 71

Topic: 10. Pathology and Oncology

A 45-year-old male presents with an incidental finding of a heavily calcified cartilage tumor within the proximal femur. He is asymptomatic. Imaging shows endosteal scalloping of less than one-third of the cortical thickness. What is the most appropriate management?

. Observation with serial radiographs
. Intralesional curettage and bone grafting
. Wide en bloc resection
. Neoadjuvant chemotherapy followed by surgery
. Radiofrequency ablation

Correct Answer & Explanation

. Observation with serial radiographs

Explanation

This presentation is typical for a benign enchondroma, given the lack of pain and minimal endosteal scalloping. Asymptomatic enchondromas do not require surgical intervention and should be managed with observation.

Question 72

Topic: 10. Pathology and Oncology

An aggressive variant of osteoblastoma, which is locally destructive and often confused with osteosarcoma, typically exhibits which of the following histologic characteristics?

. Atypical mitotic figures and prominent cartilage production
. Spindle cell proliferation in a herringbone pattern
. Epithelioid osteoblasts with abundant cytoplasm and prominent nucleoli
. Small round blue cells with CD99 positivity
. Multinucleated giant cells identical to the stromal background

Correct Answer & Explanation

. Epithelioid osteoblasts with abundant cytoplasm and prominent nucleoli

Explanation

Aggressive (or epithelioid) osteoblastoma is characterized by large, plump, epithelioid osteoblasts with prominent nucleoli. Despite its atypical appearance and locally aggressive behavior, it lacks the direct tumor bone formation by malignant cells seen in osteosarcoma.

Question 73

Topic: 10. Pathology and Oncology

A 55-year-old female presents with severe back pain. MRI shows multiple vertebral lesions. A bone scan is notably "cold" (negative) in these areas. Serum electrophoresis demonstrates an M-spike. What is the most likely diagnosis?

. Metastatic breast carcinoma
. Osteosarcoma
. Chordoma
. Multiple myeloma
. Renal cell carcinoma

Correct Answer & Explanation

. Multiple myeloma

Explanation

Multiple myeloma characteristically presents with lytic bone lesions that do not provoke reactive bone formation, resulting in a "cold" or false-negative technetium bone scan. The presence of an M-spike on SPEP confirms the monoclonal gammopathy.

Question 74

Topic: Bone Tumors

When evaluating a patient with a suspected aneurysmal bone cyst (ABC), which of the following MRI findings is highly characteristic, though not entirely specific?

. Target sign
. Fluid-fluid levels on T2-weighted imaging
. Dural tail sign
. Salt-and-pepper appearance
. Double-line sign

Correct Answer & Explanation

. Fluid-fluid levels on T2-weighted imaging

Explanation

Fluid-fluid levels on T2-weighted MRI represent blood products of varying ages settling within the cystic spaces of an ABC. While characteristic of ABCs, they can also be seen in telangiectatic osteosarcoma and giant cell tumors.

Question 75

Topic: 10. Pathology and Oncology

Which of the following primary malignancies most frequently metastasizes to the spine and predominantly presents with osteoblastic (sclerotic) lesions?

. Lung carcinoma
. Renal cell carcinoma
. Prostate carcinoma
. Thyroid carcinoma
. Melanoma

Correct Answer & Explanation

. Prostate carcinoma

Explanation

Prostate cancer uniquely stimulates osteoblast activity, resulting in characteristically osteoblastic (sclerotic) metastatic lesions in the spine and pelvis. Lung, renal, and thyroid cancers typically produce osteolytic lesions.

Question 76

Topic: 10. Pathology and Oncology

In the Enneking staging system for benign musculoskeletal tumors, an active benign tumor (Stage 2) is best described by which of the following?

. Remains static or heals spontaneously
. Grows steadily and may cause cortical expansion, but remains contained by periosteum
. Breaks through the cortex and extends into surrounding soft tissues
. Metastasizes to regional lymph nodes
. Contains skip metastases within the same bone

Correct Answer & Explanation

. Grows steadily and may cause cortical expansion, but remains contained by periosteum

Explanation

Enneking Stage 2 (active) benign tumors grow progressively and can thin or expand the cortex, but remain contained within natural barriers (capsule/periosteum). Stage 1 is latent, and Stage 3 is aggressive (breaking through barriers).

Question 77

Topic: 10. Pathology and Oncology

A biopsy of a lytic bone lesion reveals blood-filled vascular spaces lacking an endothelial lining, surrounded by fibrous septae containing giant cells and woven bone. What is the diagnosis?

. Unicameral bone cyst
. Hemangioma
. Telangiectatic osteosarcoma
. Aneurysmal bone cyst
. Giant cell tumor

Correct Answer & Explanation

. Aneurysmal bone cyst

Explanation

The histologic hallmark of an aneurysmal bone cyst is the presence of cavernous, blood-filled spaces that lack true endothelial linings, separated by cellular fibrous septae containing giant cells.

Question 78

Topic: 10. Pathology and Oncology

A 21-year-old female presents with a destructive, eccentric, lytic lesion in the distal femur epiphysis. Chest CT reveals asymptomatic small pulmonary nodules. Biopsy of the femoral lesion confirms Giant Cell Tumor (GCT). How should the pulmonary nodules be managed?

. Palliative care, as this represents Stage IV terminal disease
. Immediate systemic chemotherapy with doxorubicin and cisplatin
. Surgical resection or close observation, as they represent benign pulmonary implants
. High-dose radiation therapy to the chest
. Radioactive iodine ablation

Correct Answer & Explanation

. Surgical resection or close observation, as they represent benign pulmonary implants

Explanation

Approximately 2-3% of giant cell tumors produce "benign pulmonary implants." These are histologically identical to the primary tumor and are not considered true malignant metastases; they are often managed with observation or surgical wedge resection.

Question 79

Topic: 10. Pathology and Oncology

Which of the following statements is true regarding the risk of malignant transformation in patients with osteoblastoma?

. Malignant transformation occurs in nearly 25% of cases.
. It is extremely rare but has been reported, usually transforming into osteosarcoma.
. Transformation is exclusively linked to prior radiation therapy.
. The risk is highest in lesions measuring less than 1 cm.
. Osteoblastomas never undergo malignant transformation under any circumstances.

Correct Answer & Explanation

. It is extremely rare but has been reported, usually transforming into osteosarcoma.

Explanation

While osteoblastomas are benign, rare cases of malignant transformation into osteosarcoma have been documented, particularly in recurrent or aggressive variants. This contrasts with osteoid osteomas, which have virtually zero malignant potential.

Question 80

Topic: 10. Pathology and Oncology
Osteochondromatosis is a hereditary genetic disorder that is caused by:
. Mutation in the fibrillin-1 gene
. Translocation between chromosomes 9 and 22
. Mutation in the g-fos gene
. Translocation between chromosomes 11 and 22
. Mutation in the EXT1, EXT2, and/or EXT3 genes

Correct Answer & Explanation

. Mutation in the EXT1, EXT2, and/or EXT3 genes

Explanation

Osteochondromatosis (also known as hereditary multiple exostoses) is a genetic disorder that is autosomal dominant with incomplete penetrance in women. The genetic defect occurs on the EXT1, EXT2, and EXT3 genes located on chromosome 8q24. Mutation in the fibrillin-1 gene is seen in patients with Marfan syndrome. Translocation between chromosomes 9 and 22 is seen in myxoid chondrosarcoma. Mutation in the g-fos gene is seen in patients with Ollier's disease. Translocation between chromosomes 11 and 22 is present in patients with Ewing's tumor.

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