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10. Pathology and Oncology MCQs

Practice Set 3 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 41

Topic: 10. Pathology and Oncology

A 45-year-old male undergoes MRI of the shoulder for rotator cuff pathology, which incidentally reveals a 4 cm cartilage-type lesion in the proximal humerus. Which of the following radiographic features is most suggestive of a low-grade chondrosarcoma rather than a benign enchondroma?

. Stippled calcification
. Presence in the appendicular skeleton
. Endosteal scalloping greater than two-thirds of the cortical thickness
. Lack of periosteal reaction
. Size less than 5 cm

Correct Answer & Explanation

. Endosteal scalloping greater than two-thirds of the cortical thickness

Explanation

Differentiating benign enchondromas from low-grade chondrosarcomas is challenging. Pain, cortical thickening, periosteal reaction, and deep endosteal scalloping (greater than two-thirds of the cortex) strongly favor chondrosarcoma.

Question 42

Topic: 10. Pathology and Oncology

A 7-year-old boy presents with localized pain and swelling over the clavicle. Radiographs show a lytic, poorly marginated lesion with periosteal reaction. Biopsy reveals Langerhans cells admixed with eosinophils. Electron microscopy of the diagnostic cells would most likely demonstrate which of the following?

. Weibel-Palade bodies
. Birbeck granules
. Neurosecretory granules
. Weitbrecht ligaments
. Russell bodies

Correct Answer & Explanation

. Birbeck granules

Explanation

Eosinophilic granuloma is a localized form of Langerhans cell histiocytosis. Diagnosis is confirmed by the presence of S-100 and CD1a positive Langerhans cells, which uniquely contain tennis-racket shaped Birbeck granules on electron microscopy.

Question 43

Topic: 10. Pathology and Oncology

A 12-year-old boy has an incidental finding of an eccentric, multiloculated, radiolucent lesion with a sclerotic rim in the distal femoral metaphysis following minor trauma. He is asymptomatic. Which of the following is the most appropriate management?

. Core needle biopsy
. Curettage and bone grafting
. Prophylactic internal fixation
. Reassurance and clinical observation
. Radiofrequency ablation

Correct Answer & Explanation

. Reassurance and clinical observation

Explanation

The radiographic findings are classic for a non-ossifying fibroma (NOF), a benign, self-limiting fibro-osseous defect. Because it is asymptomatic and an incidental finding, reassurance and observation are indicated as these lesions typically ossify and resolve after skeletal maturity.

Question 44

Topic: 10. Pathology and Oncology

A secondary aneurysmal bone cyst (ABC) is most commonly found in association with which of the following primary benign bone tumors?

. Giant cell tumor
. Osteochondroma
. Enchondroma
. Osteoid osteoma
. Non-ossifying fibroma

Correct Answer & Explanation

. Giant cell tumor

Explanation

Secondary ABCs account for up to 30% of all ABCs and are engrafted on a preexisting bone lesion. They are most frequently associated with giant cell tumors, chondroblastomas, and osteoblastomas.

Question 45

Topic: 10. Pathology and Oncology

A 24-year-old male requires surgical excision of an aggressive spinal osteoblastoma involving the C4 lamina and pedicle. Which of the following represents the most significant surgical challenge and typical reason for recurrence in these lesions?

. High rate of malignant transformation to osteosarcoma
. Incomplete resection due to proximity to neural elements and abundant bleeding
. Lack of discernible tumor margins under fluorescence
. Requirement for postoperative radiation therapy
. Multifocal skip lesions within the spinal canal

Correct Answer & Explanation

. Incomplete resection due to proximity to neural elements and abundant bleeding

Explanation

Spinal osteoblastomas are highly vascular and expand into the epidural space, making complete excision technically challenging due to profuse bleeding and proximity to the spinal cord or nerve roots. Incomplete resection is the primary cause of local recurrence.

Question 46

Topic: 10. Pathology and Oncology

Which of the following benign bone lesions carries the highest inherent risk of malignant transformation without any prior history of radiation therapy?

. Multiple hereditary exostoses
. Fibrous cortical defect
. Unicameral bone cyst
. Osteoid osteoma
. Chondroblastoma

Correct Answer & Explanation

. Multiple hereditary exostoses

Explanation

Multiple hereditary exostoses (MHE) is characterized by numerous osteochondromas. Depending on the phenotype, the lifetime risk of malignant transformation to secondary chondrosarcoma is approximately 1-5%, which is significantly higher than the other listed benign lesions.

Question 47

Topic: Bone Tumors

Radiofrequency ablation (RFA) is the treatment of choice for most osteoid osteomas. In which of the following anatomical locations is RFA generally considered contraindicated or highest risk, frequently necessitating open surgical resection?

. Proximal femur neck
. Diaphysis of the tibia
. Posterior elements of the spine near the spinal cord
. Scaphoid bone
. Iliac wing

Correct Answer & Explanation

. Posterior elements of the spine near the spinal cord

Explanation

RFA relies on thermal necrosis to destroy the nidus. It is generally contraindicated or highly hazardous if the lesion is within 1 cm of critical structures like the spinal cord or major motor nerves, due to the high risk of thermal neural injury.

Question 48

Topic: 10. Pathology and Oncology

A 60-year-old male presents with a large destructive mass in the sacrum. Biopsy reveals cells with abundant bubbly, vacuolated cytoplasm arranged in cords. What is the most likely diagnosis?

. Chondrosarcoma
. Chordoma
. Giant cell tumor
. Plasmacytoma
. Osteoblastoma

Correct Answer & Explanation

. Chordoma

Explanation

Chordomas are locally aggressive malignant tumors arising from notochord remnants, classically found in the sacrum or clivus. The hallmark histologic finding is physaliferous cells, which have abundant bubbly, vacuolated cytoplasm.

Question 49

Topic: Bone Tumors

A 14-year-old female presents with back pain and a lytic lesion involving the posterior elements of L3. An MRI shows multiple fluid-fluid levels. What is the most appropriate initial surgical management for a symptomatic, locally aggressive lesion?

. En bloc spondylectomy
. Intralesional curettage and bone grafting
. Preoperative embolization followed by intralesional excision
. Observation
. Primary radiation therapy

Correct Answer & Explanation

. Preoperative embolization followed by intralesional excision

Explanation

Aneurysmal bone cysts (ABCs) in the spine typically involve the posterior elements and show fluid-fluid levels on MRI. Due to their high vascularity, preoperative embolization followed by aggressive intralesional curettage is the standard treatment to minimize blood loss.

Question 50

Topic: Bone Tumors

A 12-year-old boy presents with painful thoracic scoliosis. Imaging reveals a 1.2 cm radiolucent nidus surrounded by reactive sclerosis in the right T8 pedicle. Which of the following best describes the relationship of the lesion to the spinal curve?

. The lesion is located at the apex on the concavity of the curve.
. The lesion is located at the apex on the convexity of the curve.
. The lesion is located at the lower end vertebra of the curve.
. The lesion causes a compensatory structural curve above the nidus.
. There is no consistent relationship between the lesion and the curve.

Correct Answer & Explanation

. The lesion is located at the apex on the concavity of the curve.

Explanation

In osteoid osteoma of the spine, asymmetric muscle spasms cause a functional scoliosis. The lesion is characteristically located at the apex of the curve on the concave side.

Question 51

Topic: Bone Tumors

A 55-year-old male is diagnosed with a primary conventional chondrosarcoma of the T10 vertebral body. What is the most appropriate definitive management?

. Palliative radiation therapy
. Chemotherapy followed by intralesional curettage
. En bloc wide resection
. Intralesional curettage and cementation
. Systemic targeted therapy with denosumab

Correct Answer & Explanation

. En bloc wide resection

Explanation

Conventional chondrosarcoma is highly resistant to both chemotherapy and radiation therapy. The only potential for cure or long-term disease-free survival is en bloc wide surgical resection with negative margins.

Question 52

Topic: 10. Pathology and Oncology

A 6-year-old child presents with mid-back pain. Radiographs reveal a uniform collapse of the T7 vertebral body (vertebra plana) with adjacent disc spaces preserved. What is the most likely diagnosis?

. Ewing sarcoma
. Infection (discitis/osteomyelitis)
. Eosinophilic granuloma
. Aneurysmal bone cyst
. Osteosarcoma

Correct Answer & Explanation

. Eosinophilic granuloma

Explanation

Eosinophilic granuloma (Langerhans cell histiocytosis) classically presents in children as vertebra plana, where the vertebral body collapses completely but the adjacent intervertebral disc spaces are notably preserved.

Question 53

Topic: Bone Tumors

A 68-year-old male presents with generalized bone pain and a lytic lesion in the L4 vertebral body. Laboratory testing reveals hypercalcemia, anemia, and renal insufficiency. Serum protein electrophoresis shows an M-spike. Which of the following is most likely to be elevated in the patient's urine?

. Hydroxyproline
. Bence Jones proteins
. Alkaline phosphatase
. Osteocalcin
. N-telopeptide

Correct Answer & Explanation

. Bence Jones proteins

Explanation

The patient's presentation (CRAB symptoms: hyperCalcemia, Renal insufficiency, Anemia, Bone lesions) is classic for multiple myeloma. Bence Jones proteins (free light chains) are typically elevated and found in the urine of these patients.

Question 54

Topic: Bone Tumors

Which of the following characteristics best differentiates an osteoblastoma from an osteoid osteoma?

. Presence of a radiolucent nidus
. Relief of pain with salicylates
. Lesion size greater than 2 cm and progressive growth
. Location in the posterior elements of the spine
. Histological presence of osteoid trabeculae lined by osteoblasts

Correct Answer & Explanation

. Lesion size greater than 2 cm and progressive growth

Explanation

Osteoblastoma and osteoid osteoma share similar histology. However, osteoblastomas are distinguished by being larger than 2 cm, having progressive rather than self-limiting growth, and typically exhibiting pain that is less responsive to NSAIDs.

Question 55

Topic: 10. Pathology and Oncology

An incidental finding on a lumbar radiograph of a 50-year-old female shows coarse vertical trabeculations in the L3 vertebral body, giving a 'corduroy' appearance. Axial CT shows a 'polka dot' pattern. What is the recommended management?

. Needle biopsy to rule out malignancy
. Prophylactic vertebroplasty
. Observation only
. Radiation therapy
. Surgical decompression

Correct Answer & Explanation

. Observation only

Explanation

The imaging findings of a 'corduroy' sign on plain radiographs and a 'polka dot' sign on axial CT are pathognomonic for a vertebral hemangioma. Since it is an asymptomatic incidental finding without aggressive features, observation is the only required management.

Question 56

Topic: 10. Pathology and Oncology

A 10-year-old boy presents with progressive back pain, fever, and a sacral mass. Biopsy reveals sheets of uniform small round blue cells. Immunohistochemistry is strongly positive for CD99 and genetic testing shows a t(11;22) translocation. What is the primary treatment modality?

. En bloc resection alone
. Neoadjuvant chemotherapy followed by local control (surgery/radiation)
. Primary radiation therapy alone
. Bisphosphonate therapy
. Intralesional curettage

Correct Answer & Explanation

. Neoadjuvant chemotherapy followed by local control (surgery/radiation)

Explanation

The diagnosis is Ewing sarcoma, indicated by the small round blue cells, CD99 positivity, and t(11;22) translocation. It is a systemic disease requiring neoadjuvant multi-agent chemotherapy followed by local control with surgery and/or radiation.

Question 57

Topic: 10. Pathology and Oncology

A 75-year-old male with long-standing Paget's disease of bone develops acute, severe back pain and a rapidly enlarging mass in the lumbar spine. Serum alkaline phosphatase is markedly elevated. Biopsy confirms malignancy. What is the most likely diagnosis?

. Chondrosarcoma
. Fibrosarcoma
. Secondary osteosarcoma
. Multiple myeloma
. Metastatic prostate cancer

Correct Answer & Explanation

. Secondary osteosarcoma

Explanation

Malignant transformation in Paget's disease occurs in about 1% of cases, typically presenting with new, severe pain and a rapidly growing mass. Secondary osteosarcoma is the most common pathology and carries a very poor prognosis.

Question 58

Topic: 10. Pathology and Oncology

A 50-year-old male presents with a solitary lytic lesion in the T11 vertebral body. Biopsy confirms a monoclonal proliferation of plasma cells. Bone marrow biopsy is negative elsewhere, and skeletal survey shows no other lesions. What is the standard definitive treatment for this isolated lesion?

. Observation
. Surgical en bloc resection
. Local definitive radiation therapy
. Systemic chemotherapy only
. Denosumab therapy

Correct Answer & Explanation

. Local definitive radiation therapy

Explanation

A solitary bone plasmacytoma is a localized proliferation of malignant plasma cells without systemic myeloma. The treatment of choice is local definitive radiation therapy, to which the tumor is highly sensitive.

Question 59

Topic: 10. Pathology and Oncology
A 60-year-old woman presents with a solitary metastatic spine lesion from follicular thyroid carcinoma at L1, causing mechanical instability but no neurological deficit. She has a life expectancy of >5 years. What is the most appropriate surgical strategy?
. Intralesional curettage and cementation
. En bloc resection (spondylectomy) and stabilization
. Palliative posterior fusion without tumor resection
. Kyphoplasty alone
. Laminectomy alone

Correct Answer & Explanation

. En bloc resection (spondylectomy) and stabilization

Explanation

In a patient with a long life expectancy, an isolated spinal metastasis from a relatively radioresistant tumor (like thyroid or renal cell carcinoma), and mechanical instability, en bloc resection is indicated. This provides the best chance for local disease control and prolonged survival.

Question 60

Topic: Bone Tumors

A 20-year-old male with multiple hereditary exostoses (MHE) presents with slowly progressive myelopathy. MRI shows a bony outcropping from the C2 lamina compressing the spinal cord. The cartilage cap thickness is 0.5 cm. What is the most likely diagnosis and appropriate management?

. Chondrosarcoma; requires en bloc resection
. Osteochondroma; requires simple excision and decompression
. Osteoblastoma; requires curettage and bone grafting
. Osteoid osteoma; requires radiofrequency ablation
. Chordoma; requires proton beam therapy

Correct Answer & Explanation

. Osteochondroma; requires simple excision and decompression

Explanation

Spinal osteochondromas can cause compressive myelopathy, especially in patients with MHE. A cartilage cap thickness of <1.5-2.0 cm in an adult suggests a benign lesion, and simple excision with decompression is the standard treatment.

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