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 2301
Topic: 10. Pathology and Oncology
A 51-year-old woman has had progressively increasing right knee pain for the past 6 months. She has a history of metastatic renal cell carcinoma to the lung and the skeletal system. Radiographs are seen in Figures 18a and 18b. The next step in management of the right distal femur lesion should consist of
Correct Answer & Explanation
. a technetium Tc 99m bone scan and AP and lateral radiographs of the entire right femur.
Explanation
In a patient with known metastatic disease, the surgeon must rule out additional lesions throughout the femur prior to surgical management. Lesions located in the diaphysis or in the peritrochanteric region may influence the surgical procedure. Frassica FJ, Gitelis S, Sim FH: Metastatic bone disease: General principles, pathophysiology, evaluation, and biopsy. Instr Course Lect 1992;41:293-300.
Question 2302
Topic: 10. Pathology and Oncology
A 73-year-old man reports increasing back and lower extremity pain. A bone scan is shown in Figure 31. What is the most likely diagnosis?
Correct Answer & Explanation
. Metastatic prostate cancer
Explanation
The bone scan reveals lesions throughout the skeleton. The patient's age, gender, and pain pattern are consistent with metastatic prostate cancer. Multiple myeloma typically does not have enough osteoblastic activity to produce this bone scan. The patient's age is not consistent with metastatic neuroblastoma (a pediatric disease). Polyostotic fibrous dysplasia may involve multiple active lesions in younger patients but does not have such a widespread distribution of lesions. Hodgkin's lymphoma can involve bone, but the widespread discrete appearance on this bone scan is most consistent with metastatic prostate cancer. In a patient with widespread bone metastases from prostate cancer, bisphosphonates may play a critical role in treatment by decreasing pain and the number of fractures. Roudier MP, Vesselle H, True LD, Higano CS, Ott SM, King SH, Vessella RL: Bone histology at autopsy and matched bone scintigraphy findings in patients with hormone refractory prostate cancer: The effect of bisphosphonate therapy on bone scintigraphy results. Clin Exp Metastasis 2003;20:171-180.
Question 2303
Topic: 10. Pathology and Oncology
A 54-year-old woman underwent prophylactic intramedullary fixation for an impending fracture of her right femur secondary to metastatic breast cancer. A bone scan revealed a second lesion in her inferior pubic ramus. Her oncologist has recommended that she receive the intravenous bisphosphonate, zoledronic acid, because the medication would
Correct Answer & Explanation
. reduce processing of future bone metastases.
Explanation
Bisphosphonates have been reported to reduce the incidence of new osseous lesions and prevent an increase in size of existing lesions. Zoledronic acid has been reported in clinical trials to decrease the skeletal complications of patients with multiple myeloma and with bone metastases from solid tumors. Results also have demonstrated that zoledronic acid delays the initial onset of bone complications by more than 2 months in patients with non-small-cell lung cancer and other solid tumors. In two placebo-controlled clinical studies of zoledronic acid conducted in patients with bone metastases from prostate cancer or other solid tumors, there was a decrease in the number of patients with skeletal-related events compared to placebo, and the time to the first skeletal-related event was delayed. Mundy GR, Yoneda T: Bisphosphonates as anticancer drugs. N Engl J Med 1998;339:398-400.
Question 2304
Topic: 10. Pathology and Oncology
An 11-year-old girl has wrist pain. Figure 4a shows the radiograph, and Figures 4b and 4c show the low- and medium-power photomicrographs of a lesion in the distal radius. What is the most likely diagnosis?
Correct Answer & Explanation
. Aneurysmal bone cyst
Explanation
The radiograph shows an osteolytic eccentric lesion in the metaphyseal-diaphyseal region of the bone, and the photomicrographs show an aneurysmal bone cyst. The low-power photomicrograph shows large empty spaces with fibrous stroma and multinucleated giant cells. The red area in the center is hemorrhage in the stroma. The large empty spaces are cysts, which would be filled with blood in vivo. The medium-power photomicrograph shows a large cyst-like space and hemorrhage in the surrounding stoma. Giant cell tumors have "sheets" of giant cells. A nonossifying fibroma would have spindle cells, and a unicameral bone cyst may have a few giant cells, but blood is rare. Springfield DS, Gebhardt MC: Bone and soft tissue tumors, in Morrissy RT, Weinstein SL (eds): Lovell and Winter's Pediatric Orthopaedics, ed 5. Philadelphia, PA, Lippincott Williams and Wilkins, 2001, pp 540-542.
Question 2305
Topic: 10. Pathology and Oncology
A 12-year-old girl has had right knee pain for the past 3 months. Radiographs and a coronal T2-weighted MRI scan are shown in Figures 10a through 10c. A biopsy specimen is shown in Figure 10d. What is the most appropriate treatment for this lesion?
Correct Answer & Explanation
. Neoadjuvant chemotherapy followed by wide resection and reconstruction
Explanation
The radiographs show a lytic lesion in the right proximal tibia that has a high fluid content based on the MRI findings. The radiographic appearance is consistent with either telangiectatic osteosarcoma or aneurysmal bone cyst. Low-magnification histology shows a lesion resembling an aneurysmal bone cyst, with blood lakes separated by cellular septa. However, high-magnification shows severe cytologic atypia, indicative of a telangiectatic osterosarcoma. The appropriate treatment is neoadjuvant chemotherapy followed by wide resection and reconstruction of the lesion. Unni KK: Dahlin's Bone Tumors: General Aspects and Data on 11,087 Cases, ed 5. Philadelphia, PA, Lippincott-Raven, 1996, pp 143-160.
Question 2306
Topic: 10. Pathology and Oncology
A 55-year-old man has had a mass in his right thigh for the past 2 months. An MRI scan and biopsy specimens are shown in Figures 55a through 55c. What is the most likely diagnosis?
Correct Answer & Explanation
. Extraskeletal myxoid chondrosarcoma
Explanation
The histology shows extraskeletal myxoid chondrosarcoma, characterized by abundant blue myxoid matrix with cords and nests of small tumor cells. Treatment consists of wide resection. Despite the name, hyaline cartilage is not a common component of these tumors. Adult rhabdomyosarcoma and malignant fibrous histiocytoma are highly pleomorphic sarcomas often containing multinucleated giant cells. Myxoid liposarcoma contains a prominent capillary network and lipoblasts. Myxoma is less cellular than extraskeletal myxoid chondrosarcoma and does not have a cord-like arrangement of tumor cells.
Question 2307
Topic: 10. Pathology and Oncology
A 60-year-old male with a history of metastatic renal cell carcinoma (RCC) presents with acute onset, intractable left hip pain and inability to bear weight. Radiographs and MRI reveal a large lytic lesion involving the subtrochanteric region of the left femur, with cortical destruction and an impending pathologic fracture. His Enneking score for pain is 3, stability is 2, and function is 2. He has otherwise stable systemic disease and a good prognosis.
What is the most appropriate surgical management for this patient?
Correct Answer & Explanation
. Resection of the subtrochanteric lesion and reconstruction with a proximal femoral endoprosthesis.
Explanation
This patient has an impending pathologic fracture of the subtrochanteric femur due to metastatic renal cell carcinoma (RCC). The lesion is large, lytic, with cortical destruction, leading to intractable pain and inability to bear weight. His Mirels score (pain 3 + stability 2 + size 2/3 cortical destruction = 7 or 8) is high, indicating a high risk of fracture or actual impending fracture. RCC metastases are often highly vascular and relatively resistant to conventional radiation therapy alone, making local control and mechanical stability paramount, especially given his good overall prognosis.Option A (EBRT only) is insufficient. While radiation can help with pain control, it does not provide immediate mechanical stability for an impending fracture in a high-load-bearing area like the subtrochanteric femur. RCC is also known to be radioresistant.Option B (Prophylactic intramedullary nailing of the femur) would provide stability for an impending fracture and is a common approach for diaphyseal or less comminuted subtrochanteric lesions. However, for alargelytic lesion withcortical destructionin the subtrochanteric region due to RCC (which is known for poor healing and being very lytic), nailing alone might not be sufficient to prevent hardware failure or provide adequate local control, especially if significant bone is destroyed. It also might not provide full pain relief if the tumor is actively destroying bone.Option C (Curettage and cementation with prophylactic fixation) might be suitable for smaller, contained lesions or those in less mechanically demanding areas, but for a large, load-bearing lytic lesion in the subtrochanteric region from RCC, it might not offer sufficient long-term stability and local control.Option D (Resection of the subtrochanteric lesion and reconstruction with a proximal femoral endoprosthesis) is the most appropriate option. Given the large lytic lesion, cortical destruction, and the aggressive nature of RCC metastases in bone, a wide resection of the involved bone offers the best local tumor control. Reconstruction with a proximal femoral endoprosthesis provides immediate, durable mechanical stability, allows for immediate weight-bearing, and significantly improves pain and function. This approach is particularly indicated for large, destructive lesions in critical load-bearing areas, especially from radioresistant tumors in patients with a good prognosis.Option E (Open biopsy followed by observation) is incorrect. A biopsy is needed for definitive diagnosis if not already confirmed, but observation is not appropriate given the impending fracture and severe symptoms. Surgical stabilization is necessary.
Question 2308
Topic: 10. Pathology and Oncology
A 24-year-old female presents with recurrent pain and swelling around her left knee. MRI reveals an expansile, lytic lesion in the distal femur, extending to the subchondral bone, with sclerotic margins. Biopsy confirms giant cell tumor of bone.
Which of the following adjuvant treatments is most effective in reducing local recurrence rates following intralesional curettage for this tumor?
Correct Answer & Explanation
. Cryoablation or high-speed burring of the cavity.
Explanation
Giant cell tumor of bone (GCT) is a benign but locally aggressive tumor with a propensity for local recurrence after intralesional curettage. To reduce recurrence rates, adjuvant treatments are often used. Cryoablation (using liquid nitrogen) or high-speed burring of the tumor cavity after curettage are established and highly effective local adjuvant treatments that kill residual tumor cells in the margins, significantly reducing recurrence. Denosumab (a RANKL inhibitor) is a systemic agent used for unresectable GCTs, recurrent GCTs, or as a preoperative adjunct to facilitate surgery, but it is not typically the primary adjuvant therapyafterintralesional curettage in a resectable lesion. Radiation therapy (pre- or postoperative) is generally reserved for unresectable lesions or recurrent cases where surgery is not feasible due to its potential for malignant transformation. Chemotherapy has no role in GCT.
Question 2309
Topic: 10. Pathology and Oncology
A 6-year-old child presents with a Limberg flap-like skin lesion on the anterior aspect of the lower leg following a severe open tibia fracture. The lesion is firm, hyperpigmented, and shows no signs of active infection. Biopsy reveals mature bone tissue within the soft tissues. What is the MOST likely diagnosis?
Correct Answer & Explanation
. Heterotopic ossification (HO).
Explanation
The clinical scenario describes a soft tissue mass containing mature bone tissue following a severe trauma, consistent with heterotopic ossification (HO). HO is the formation of lamellar bone in non-osseous tissues. It is a known complication following severe trauma, especially open fractures, burns, and head injuries. Pyogenic granuloma is a benign vascular lesion. Soft tissue sarcoma is a malignant tumor, which a biopsy revealing 'mature bone tissue' would typically rule out. Keloid scar is an overgrowth of fibrous tissue, not bone. Chronic osteomyelitis would show signs of infection and necrotic bone, not mature bone formation in soft tissue. The 'Limberg flap-like' description might be a distractor for a specific wound closure technique, but the key is 'mature bone tissue within the soft tissues' following trauma.
Question 2310
Topic: 10. Pathology and Oncology
A 55-year-old male presents with persistent right thigh pain and swelling. An MRI reveals a large, ill-defined lesion in the distal femur suggestive of a high-grade sarcoma. Surgical planning is underway for a diagnostic biopsy. Which of the following principles regarding biopsy technique is MOST critical to ensure the success of a subsequent limb salvage procedure?
Correct Answer & Explanation
. Ensuring the biopsy incision is placed in line with the planned definitive surgical approach.
Explanation
The most critical principle in performing a biopsy for a suspected malignant bone tumor is to ensure that the biopsy incision and tract are placed in line with the planned definitive surgical approach. This allows the entire biopsy tract, including skin, subcutaneous tissue, and muscle, to be completely excised en bloc with the tumor during the limb salvage procedure. Improper biopsy placement can contaminate adjacent tissue planes or compartments, potentially compromising the ability to achieve clean surgical margins during definitive surgery and increasing the risk of local recurrence. While obtaining an adequate tissue sample is important for diagnosis, it should not compromise the surgical plan. Needle biopsies are preferred over open biopsies to minimize contamination, but their placement remains paramount. Chemotherapy is typically initiated after diagnosis and staging, not immediately after biopsy.
Question 2311
Topic: 10. Pathology and Oncology
A 14-year-old male presents with right distal femur pain. Imaging reveals a large, aggressive lesion. Biopsy confirms high-grade osteosarcoma. A full metastatic workup, including chest CT and bone scan, shows no evidence of distant disease. The tumor is intra-compartmental. According to the Enneking surgical staging system for malignant musculoskeletal tumors, what is the correct stage for this patient's tumor?
Correct Answer & Explanation
. Stage IIA
Explanation
The Enneking surgical staging system classifies musculoskeletal sarcomas based on grade (G), site (T), and metastasis (M). G1 is low-grade, G2 is high-grade. T1 is intra-compartmental, T2 is extra-compartmental. M0 is no regional or distant metastasis, M1 is metastasis. In this scenario: High-grade osteosarcoma = G2; Intra-compartmental = T1; No distant metastasis = M0. Therefore, the tumor is classified as Stage IIA. Stage IIB would be a high-grade, extra-compartmental tumor without metastasis (G2T2M0).
Question 2312
Topic: 10. Pathology and Oncology
A 12-year-old male presents with a painful, enlarging mass in his distal left femur. Biopsy confirms high-grade osteosarcoma. Staging studies reveal no evidence of metastatic disease. Imaging shows a large, mixed lytic and blastic lesion with cortical destruction and a soft tissue component. The multidisciplinary tumor board recommends neoadjuvant chemotherapy followed by surgical resection. Considering limb salvage surgery, which of the following is the most critical principle to ensure oncologic success?
Correct Answer & Explanation
. Achieving wide surgical margins through en bloc resection, regardless of functional outcome.
Explanation
The image provided shows a lytic and blastic lesion of the distal femur, consistent with an aggressive bone tumor like osteosarcoma. For high-grade osteosarcoma, neoadjuvant chemotherapy followed by surgical resection is the standard of care. The most critical principle for oncologic success in limb salvage surgery for primary bone tumors is achieving adequate surgical margins. Surgical margins are classified as: Intralesional: Entering the tumor. Marginal: Dissecting through the pseudocapsule or reactive zone. Wide: Resecting through healthy tissue well outside the reactive zone. Radical: Resection of the entire compartment containing the tumor. A wide surgical margin is necessary to remove all gross and microscopic tumor, minimizing local recurrence. While functional outcome and limb length preservation are important considerations, they are secondary to the primary goal of tumor eradication.
Question 2313
Topic: 10. Pathology and Oncology
A 60-year-old male presents with chronic low back pain, radiculopathy, and progressive neurological deficits in both lower extremities. Imaging reveals a large sacral mass consistent with a chordoma. The tumor involves the S3 and S4 segments of the sacrum, with extension into the soft tissues and rectum. Biopsy confirms chordoma. What is the MOST appropriate surgical approach and margin goal for this tumor?
Correct Answer & Explanation
. En bloc wide resection with sacrectomy, requiring a combined anterior and posterior approach.
Explanation
The patient has a sacral chordoma involving S3 and S4 with local extension. Chordomas are slow-growing, locally aggressive malignant tumors that commonly recur if not adequately resected. The cornerstone of treatment is en bloc wide surgical resection with negative margins.Due to their location (sacrum) and extension, sacral chordomas often require complex surgical approaches, frequently a combined anterior and posterior approach, to achieve wide margins while minimizing damage to vital structures like the rectum, bladder, and nerve roots. The level of sacrectomy dictates functional outcomes (S3 or below preserves most bladder/bowel function). Intralesional or marginal resections are associated with high recurrence rates.Rationale for options:A. Intralesional debulking is associated with very high local recurrence rates and is reserved for palliative care or situations where wide resection is impossible and the goal is symptom relief, not oncologic cure.B. Marginal excision, especially via a posterior approach only for a tumor with anterior extension, is insufficient for a chordoma and would lead to high local recurrence rates.C. En bloc wide resection with sacrectomy, often requiring a combined anterior and posterior approach to achieve negative margins, is the gold standard for sacral chordomas. This is the correct answer.D. Radiation therapy is often used as an adjunct to surgery, especially for positive margins or unresectable tumors, but it is not the primary curative treatment for chordomas due to their radioresistance and the need for high doses that can damage adjacent structures.E. Complete amputation of both lower extremities is an extreme measure not indicated for a sacral chordoma, which is locally invasive but typically does not metastasize widely until late stages.
Question 2314
Topic: Bone Tumors
A 15-year-old boy presents with progressive, severe diaphyseal tibial pain that is characteristically worse at night and rapidly relieved by ibuprofen.
Radiographs show a dense sclerotic cortical thickening with a small radiolucent nidus. Which of the following best describes the pathophysiologic mechanism of this pain?
Correct Answer & Explanation
. Overexpression of cyclooxygenase-2 (COX-2) within the nidus
Explanation
The clinical presentation and radiographic description are classic for an osteoid osteoma. The intense pain, particularly at night, and dramatic relief with NSAIDs are hallmark features. The pathophysiology of this pain is driven by a high concentration of prostaglandins, specifically due to the overexpression of cyclooxygenase-2 (COX-2) within the neoplastic osteoblasts of the nidus. This leads to profound local vasodilation and stimulation of unmyelinated nerve fibers.
Question 2315
Topic: 10. Pathology and Oncology
A 65-year-old man presents with generalized bone pain, fatigue, and a recent pathological fracture of his proximal humerus. Laboratory workup reveals hypercalcemia and anemia. Serum protein electrophoresis shows a monoclonal spike. Radiographs demonstrate multiple 'punched-out' lytic lesions in his skull and pelvis. Which of the following is the most definitive diagnostic test to confirm the underlying primary pathology?
Correct Answer & Explanation
. Bone marrow biopsy
Explanation
The clinical scenario is highly indicative of Multiple Myeloma (CRAB symptoms: hyperCalcemia, Renal failure, Anemia, Bone lesions). While serum/urine electrophoresis and a skeletal survey are critical for initial evaluation, the definitive diagnosis requires a bone marrow biopsy demonstrating greater than 10% clonal plasma cells. Note that a Tc-99m bone scan is often cold or falsely negative in myeloma because the lesions are purely lytic with little to no reactive osteoblastic activity.
Question 2316
Topic: 10. Pathology and Oncology
A 32-year-old male presents with a slow-growing, painful mass in his left thigh. MRI reveals a deep soft tissue mass adjacent to the knee joint. Biopsy demonstrates a biphasic tumor with both epithelial and spindle cell components. Which of the following cytogenetic abnormalities is pathognomonic for this sarcoma?
Correct Answer & Explanation
. t(X;18) SYT-SSX
Explanation
The clinical presentation and biphasic histology indicate a synovial sarcoma. The pathognomonic chromosomal translocation for synovial sarcoma is t(X;18)(p11;q11), which results in the SYT-SSX (now often termed SS18-SSX) fusion gene. t(11;22) is characteristic of Ewing sarcoma, t(12;16) for myxoid liposarcoma, and t(2;13) for alveolar rhabdomyosarcoma.
Question 2317
Topic: 10. Pathology and Oncology
A 19-year-old male presents with deep, boring thigh pain that is significantly worse at night and dramatically relieved by oral ibuprofen. A CT scan is obtained
demonstrating a 1 cm radiolucent nidus surrounded by dense, reactive sclerotic cortical bone in the femoral diaphysis. What is the primary biochemical mediator responsible for this characteristic pain pattern?
Correct Answer & Explanation
. Prostaglandin E2 (PGE2)
Explanation
The clinical presentation and imaging are classic for an osteoid osteoma. The tumor nidus produces high levels of prostaglandins, specifically Prostaglandin E2 (PGE2), which mediate the intense, night-predominant pain. This pathophysiology explains why the pain is typically exquisitely responsive to NSAIDs (which inhibit cyclooxygenase and subsequent prostaglandin synthesis).
Question 2318
Topic: 10. Pathology and Oncology
A 35-year-old male presents with a deep, painless mass in the distal thigh. A core needle biopsy reveals a biphasic histologic pattern composed of epithelial and spindle cells. Cytogenetic analysis is most likely to identify which of the following translocations?
Correct Answer & Explanation
. t(X;18)(p11;q11)
Explanation
The diagnosis is synovial sarcoma, which characteristically features a biphasic histology and is associated with the t(X;18)(p11;q11) translocation, resulting in the SYT-SSX fusion gene. Ewing sarcoma is associated with t(11;22), and myxoid liposarcoma with t(12;16).
Question 2319
Topic: 10. Pathology and Oncology
A 15-year-old male presents with distal femur pain and a sunburst periosteal reaction on radiographs. Biopsy confirms high-grade intramedullary osteosarcoma. Which of the following factors is the most important prognostic indicator for his long-term survival?
Correct Answer & Explanation
. The degree of tumor necrosis following neoadjuvant chemotherapy.
Explanation
The most important prognostic factor for long-term survival in patients with localized high-grade osteosarcoma is the histological response to neoadjuvant chemotherapy. A favorable response is classically defined as greater than 90% tumor necrosis at the time of surgical resection, which correlates with significantly improved survival.
Question 2320
Topic: 10. Pathology and Oncology
A 12-year-old boy presents with thigh pain and swelling. Radiographs show a permeative diaphyseal lesion of the femur with an 'onion-skin' periosteal reaction. Biopsy confirms small, round, blue cells that stain positive for CD99. Which of the following chromosomal translocations is most characteristic of this pathology?
Correct Answer & Explanation
. t(11;22)(q24;q12)
Explanation
Ewing sarcoma is characterized by the t(11;22)(q24;q12) translocation, leading to the EWS-FLI1 fusion protein. t(X;18) is seen in synovial sarcoma, and t(12;16) in myxoid liposarcoma.
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