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10. Pathology and Oncology MCQs

Practice Set 345 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 6881

Topic: 10. Pathology and Oncology

A 6-year-old boy presents with an asymmetric, painless swelling on the medial aspect of his right ankle. Radiographs show an irregular, ossified mass arising from the medial epiphysis of the distal tibia. Histological examination of the lesion is most likely to resemble which of the following benign tumors?

. Chondroblastoma
. Osteoid osteoma
. Chondromyxoid fibroma
. Osteochondroma
. Enchondroma

Correct Answer & Explanation

. Osteochondroma

Explanation

Dysplasia epiphysealis hemimelica (Trevor disease) is an asymmetric overgrowth of articular cartilage, typically in the lower extremities. Histologically, it is indistinguishable from an osteochondroma, possessing a cartilage cap and underlying trabecular bone.

Question 6882

Topic: 10. Pathology and Oncology

A 5-year-old boy presents with an asymmetric, painless mass on the medial aspect of his right ankle. Radiographs reveal an osteochondroma-like cartilaginous overgrowth arising directly from the epiphysis of the distal tibia. Which of the following is the most appropriate initial management for this asymptomatic lesion?

. Immediate wide excision
. Core needle biopsy
. Observation with regular clinical and radiographic follow-up
. Prophylactic epiphysiodesis
. Neoadjuvant chemotherapy

Correct Answer & Explanation

. Observation with regular clinical and radiographic follow-up

Explanation

This presentation is classic for Dysplasia Epiphysealis Hemimelica (Trevor disease), a benign developmental anomaly of the epiphysis. Observation is the standard of care for asymptomatic lesions, with surgical excision reserved for cases causing pain, mechanical block, or progressive deformity.

Question 6883

Topic: 10. Pathology and Oncology

A 7-year-old boy with a known history of Dysplasia Epiphysealis Hemimelica (Trevor disease) involving the medial aspect of his right knee is seen for follow-up. The parents are highly anxious about the potential for the cartilaginous lesion to become cancerous. What is the estimated risk of malignant transformation of this lesion?

. 0%
. 1 to 5%
. 10 to 15%
. 20 to 25%
. Greater than 50%

Correct Answer & Explanation

. 0%

Explanation

Dysplasia Epiphysealis Hemimelica is a benign developmental disorder of the epiphysis. Unlike osteochondromas, there are no documented cases of malignant transformation to chondrosarcoma in Trevor disease.

Question 6884

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a 2-month history of worsening mid-thigh pain that awakens him at night, accompanied by low-grade fevers. Radiographs of the femur reveal a permeative, destructive diaphyseal lesion with an "onion-skin" periosteal reaction. A biopsy is performed. Which of the following genetic translocations is most characteristic of this patient's likely diagnosis?

. t(11;22)
. t(9;22)
. t(X;18)
. t(12;16)
. t(2;13)

Correct Answer & Explanation

. t(11;22)

Explanation

Correct Answer: AThe clinical and radiographic presentation (diaphyseal lesion, onion-skin periosteal reaction, systemic symptoms) is classic for Ewing sarcoma. The most common genetic translocation associated with Ewing sarcoma is t(11;22)(q24;q12), which results in the EWS-FLI1 fusion protein. This translocation is present in approximately 85% of cases and is a key diagnostic marker.

Question 6885

Topic: 10. Pathology and Oncology

A 16-year-old male presents with a 3-month history of dull, aching pain in his right knee. Radiographs reveal a mixed lytic and blastic lesion in the distal femoral metaphysis with a "sunburst" periosteal reaction and a Codman triangle. Biopsy confirms the diagnosis of osteosarcoma. Which of the following is the most appropriate standard treatment regimen for this patient?

. Primary amputation followed by radiation therapy
. Neoadjuvant chemotherapy, wide surgical resection, and adjuvant chemotherapy
. Wide surgical resection alone
. Radiation therapy followed by wide surgical resection
. Intralesional curettage and bone grafting

Correct Answer & Explanation

. Neoadjuvant chemotherapy, wide surgical resection, and adjuvant chemotherapy

Explanation

Correct Answer: BThe standard of care for high-grade, non-metastatic osteosarcoma is neoadjuvant (preoperative) chemotherapy, followed by wide surgical resection (limb-salvage surgery if feasible), and then adjuvant (postoperative) chemotherapy. This approach treats micrometastatic disease early, shrinks the primary tumor to facilitate resection, and allows for histological evaluation of tumor necrosis, which is a key prognostic factor. Osteosarcoma is generally considered radioresistant.

Question 6886

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a 2-month history of worsening right thigh pain, especially at night, accompanied by a low-grade fever. Radiographs of the femur reveal a permeative diaphyseal lesion with a prominent "onion-skin" periosteal reaction. What is the most likely diagnosis?

. Osteosarcoma
. Chondrosarcoma
. Ewing's sarcoma
. Osteoid osteoma
. Multiple myeloma

Correct Answer & Explanation

. Ewing's sarcoma

Explanation

Correct Answer: CEpidemiology:Ewing's sarcoma is the second most common primary malignant bone tumor in children, following osteosarcoma. It typically affects the diaphysis of long bones (e.g., femur, tibia) and the pelvis.Radiographic Findings:The classic radiographic appearance is a permeative, destructive diaphyseal lesion with an "onion-skin" (lamellated) periosteal reaction, representing sequential layers of new bone formation in response to the rapidly growing tumor.Differential Diagnosis:Osteosarcoma typically occurs in the metaphysis and presents with a "sunburst" pattern or Codman's triangle. Chondrosarcoma is more common in adults and shows "popcorn" calcifications. Osteoid osteoma presents with a radiolucent nidus surrounded by sclerotic bone and causes night pain relieved by NSAIDs.

Question 6887

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful, swollen mass on his mid-thigh. Radiographs show a permeative, diaphyseal lesion with an "onion-skin" periosteal reaction. A biopsy is performed, confirming a small round blue cell tumor. Which of the following chromosomal translocations is most characteristic of this diagnosis?

. t(9;22)
. t(11;22)
. t(12;16)
. t(X;18)
. t(2;13)

Correct Answer & Explanation

. t(11;22)

Explanation

Correct Answer: B (t(11;22))The clinical and radiographic presentation is classic for Ewing sarcoma. Ewing sarcoma is characterized by the t(11;22)(q24;q12) translocation in approximately 85% of cases, which results in the EWS-FLI1 fusion protein. Other translocations include t(9;22) seen in myxoid chondrosarcoma and CML, t(12;16) seen in myxoid liposarcoma, t(X;18) seen in synovial sarcoma, and t(2;13) seen in alveolar rhabdomyosarcoma.

Question 6888

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a 2-month history of worsening mid-thigh pain, which frequently awakens him at night. Radiographs of the femur reveal a diaphyseal permeative lytic lesion with an "onion-skin" periosteal reaction. Biopsy shows sheets of small round blue cells. Which of the following chromosomal translocations is most characteristic of this tumor?

. t(11;22)
. t(9;22)
. t(12;16)
. t(X;18)
. t(2;13)

Correct Answer & Explanation

. t(11;22)

Explanation

Correct Answer: AThe clinical and radiographic presentation is classic for Ewing sarcoma, a highly malignant primary bone tumor that typically affects the diaphysis of long bones in children and young adults. The characteristic chromosomal translocation is t(11;22)(q24;q12), which is found in approximately 85% of cases and results in the EWS-FLI1 fusion protein. t(9;22) is seen in chronic myelogenous leukemia (Philadelphia chromosome) and some extraskeletal myxoid chondrosarcomas. t(12;16) is characteristic of myxoid liposarcoma. t(X;18) is seen in synovial sarcoma. t(2;13) is seen in alveolar rhabdomyosarcoma.

Question 6889

Topic: 10. Pathology and Oncology

A 22-year-old male presents with a painless, hard mass around his distal medial thigh that he has had for years. Recently, he noticed it has slightly increased in size. Radiographs show a pedunculated bony exostosis pointing away from the knee joint, with continuous medullary cavity communication with the native femur. Which of the following features is most concerning for malignant transformation of this lesion?

. Cartilage cap thickness of 1.0 cm
. Cartilage cap thickness of 2.5 cm
. Pedunculated morphology
. Location in the distal femur
. Communication of the medullary canal

Correct Answer & Explanation

. Cartilage cap thickness of 2.5 cm

Explanation

Correct Answer: BThe lesion described is an osteochondroma, the most common benign bone tumor. Malignant transformation to secondary chondrosarcoma occurs in <1% of solitary osteochondromas (the risk is higher in multiple hereditary exostoses). The most reliable imaging sign of malignant transformation in an adult is a cartilage cap thickness greater than 2.0 cm (some sources use >1.5 cm as a threshold for concern). A cap of 2.5 cm is highly concerning for secondary chondrosarcoma and warrants biopsy or wide excision. Pedunculated morphology, location in the metaphysis of long bones, and medullary continuity are standard diagnostic features of benign osteochondromas.

Question 6890

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with a 2-month history of worsening thigh pain and low-grade fevers. Radiographs reveal a permeative diaphyseal lesion in the femur with an "onion-skin" periosteal reaction. A biopsy is performed. Which of the following chromosomal translocations is most characteristic of this patient's likely diagnosis?

. t(11;22)
. t(9;22)
. t(12;16)
. t(2;13)
. t(X;18)

Correct Answer & Explanation

. t(11;22)

Explanation

Correct Answer: t(11;22)The clinical presentation and radiographic findings (permeative diaphyseal lesion, "onion-skin" periosteal reaction) are classic for Ewing's sarcoma. Ewing's sarcoma is a small round blue cell tumor characterized by the t(11;22)(q24;q12) chromosomal translocation in approximately 85-90% of cases. This translocation fuses the EWS gene on chromosome 22 with the FLI1 gene on chromosome 11, creating an aberrant transcription factor that drives oncogenesis. Other notable translocations include t(X;18) in synovial sarcoma, t(12;16) in myxoid liposarcoma, and t(2;13) in alveolar rhabdomyosarcoma.

Question 6891

Topic: Bone Tumors

A 19-year-old male presents with worsening right thigh pain that is particularly severe at night and dramatically improves with ibuprofen. Radiographs show a small radiolucent nidus surrounded by dense sclerotic bone in the proximal femoral diaphysis. What is the primary biochemical mediator responsible for this patient's pain pattern?

. Interleukin-1
. Tumor necrosis factor-alpha
. Prostaglandin E2
. Leukotriene B4
. Transforming growth factor-beta

Correct Answer & Explanation

. Prostaglandin E2

Explanation

Osteoid osteomas characteristically cause nocturnal pain that is relieved by NSAIDs. This is due to the high levels of Prostaglandin E2 produced by the nidus, which NSAIDs effectively inhibit.

Question 6892

Topic: 10. Pathology and Oncology

A 68-year-old male presents with dull, aching pain in his right shoulder. Radiographs reveal a lytic lesion in the proximal humerus with intralesional "popcorn" calcifications and endosteal scalloping. Biopsy confirms a grade II chondrosarcoma. Which of the following is the most appropriate management?

. Neoadjuvant chemotherapy followed by wide local excision
. Intralesional curettage and bone grafting
. Wide surgical resection alone
. Primary radiation therapy
. Observation with serial radiographs

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Intermediate and high-grade chondrosarcomas are generally resistant to both chemotherapy and radiation therapy. The gold standard for definitive management is wide surgical resection with negative margins.

Question 6893

Topic: 10. Pathology and Oncology

A 16-year-old boy completes neoadjuvant chemotherapy for an osteosarcoma of the distal femur and subsequently undergoes wide local excision. Pathological analysis of the resected specimen is performed. Which of the following is the most reliable prognostic indicator for long-term patient survival?

. Tumor volume at initial presentation
. Histologic subtype of the tumor
. Percentage of tumor necrosis
. Presence of skip metastases on preoperative MRI
. Age of the patient at diagnosis

Correct Answer & Explanation

. Percentage of tumor necrosis

Explanation

The histological response to neoadjuvant chemotherapy, specifically the percentage of tumor necrosis, is the most powerful prognostic factor in osteosarcoma. Greater than 90% necrosis is classified as a good response and correlates strongly with improved survival rates.

Question 6894

Topic: 10. Pathology and Oncology

A 60-year-old female presents with a slowly enlarging, painful mass in her right pelvis. Radiographs show a lytic lesion with punctate, "rings and arcs" calcifications. Biopsy confirms a grade 2 conventional chondrosarcoma. Which of the following is the most appropriate primary treatment modality?

. Neoadjuvant chemotherapy followed by wide resection
. Radiation therapy followed by wide resection
. Wide surgical resection alone
. Intralesional curettage and bone grafting
. Neoadjuvant chemotherapy, wide resection, and adjuvant radiation

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Conventional chondrosarcomas are notoriously resistant to both chemotherapy and radiation therapy. The standard of care for an intermediate or high-grade conventional chondrosarcoma is wide surgical resection alone.

Question 6895

Topic: 10. Pathology and Oncology

An 18-year-old male is diagnosed with high-grade osteosarcoma of the distal femur. He undergoes a standard protocol of neoadjuvant chemotherapy followed by wide surgical resection and limb salvage. Histopathologic analysis of the resected specimen is performed. Which of the following is the most significant independent prognostic factor for long-term survival in this patient?

. Initial size of the primary tumor
. Baseline serum alkaline phosphatase levels
. Histologic tumor necrosis percentage after neoadjuvant chemotherapy
. Width of the normal tissue margin exceeding 2 cm
. Presence of an associated pathologic fracture at presentation

Correct Answer & Explanation

. Histologic tumor necrosis percentage after neoadjuvant chemotherapy

Explanation

The percentage of histologic tumor necrosis following neoadjuvant chemotherapy (Huvos grading) is the most reliable prognostic indicator for overall survival in osteosarcoma. Greater than 90% necrosis indicates a good chemotherapeutic response and strongly correlates with improved long-term outcomes.

Question 6896

Topic: 10. Pathology and Oncology

A 2-year-old boy presents with isolated hemihypertrophy and a 2.5 cm leg length discrepancy. Which routine screening test is mandatory for this patient due to associated systemic risks?

. Annual MRI of the entire neuraxis
. Serial full-body skeletal surveys
. Regular abdominal ultrasound
. Echocardiography every 6 months
. Cranial ultrasound and EEG

Correct Answer & Explanation

. Regular abdominal ultrasound

Explanation

Isolated hemihypertrophy can be associated with Beckwith-Wiedemann syndrome, which carries an increased risk of embryonal tumors (such as Wilms tumor and hepatoblastoma). Regular screening with abdominal ultrasound is the standard of care until roughly age 7.

Question 6897

Topic: 10. Pathology and Oncology

A 60-year-old male with a 30-year history of chronic post-traumatic tibial osteomyelitis presents with increasing pain, a foul-smelling exudate, and a newly enlarging, fungating mass at the sinus tract opening. Biopsy of the mass will most likely reveal which of the following?

. Osteosarcoma
. Malignant fibrous histiocytoma
. Squamous cell carcinoma
. Basal cell carcinoma
. Ewing sarcoma

Correct Answer & Explanation

. Squamous cell carcinoma

Explanation

A Marjolin ulcer is a malignant degeneration that occurs in chronic wounds, most notoriously chronic osteomyelitis sinus tracts. The most common histology is squamous cell carcinoma, which tends to be highly aggressive when arising in this setting.

Question 6898

Topic: 10. Pathology and Oncology

A 65-year-old male with long-standing Paget's disease of the pelvis presents with new-onset, severe, and progressively worsening unilateral hip pain. Radiographs reveal progressive osteolysis and cortical destruction. What is the most likely diagnosis?

. Aseptic loosening of the hip joint
. Chondrosarcoma
. Secondary osteosarcoma
. Metastatic prostate cancer
. Ewing sarcoma

Correct Answer & Explanation

. Secondary osteosarcoma

Explanation

Secondary osteosarcoma is a rare but highly lethal complication of Paget's disease, occurring in about 1% of patients. It typically presents with new-onset severe pain and aggressive lytic bone destruction in an area previously affected by Pagetic changes.

Question 6899

Topic: 10. Pathology and Oncology

A 72-year-old man with known long-standing Paget's disease of the right femur presents with sudden-onset, severe right thigh pain over the past 3 weeks. Radiographs reveal a new, destructive, poorly marginated lytic lesion with cortical breakthrough. What is the most appropriate next step in management?

. Initiate intravenous bisphosphonate therapy
. Perform cross-sectional imaging (MRI) and a core needle biopsy
. Prophylactic intramedullary nailing of the right femur
. Empirical radiation therapy
. Increase calcium and vitamin D supplementation

Correct Answer & Explanation

. Perform cross-sectional imaging (MRI) and a core needle biopsy

Explanation

Paget's disease has a ~1% risk of malignant transformation, most commonly to secondary osteosarcoma. A sudden change in clinical symptoms accompanied by a new destructive lesion requires a prompt oncology workup, including MRI and biopsy.

Question 6900

Topic: 10. Pathology and Oncology

A 50-year-old woman presents with a pathologic fracture through a highly vascular, lytic lesion in her proximal humerus. Labs reveal a serum calcium of 11.5 mg/dL, low phosphate, and a highly elevated intact PTH. She reports a history of recurrent kidney stones. What is the most likely diagnosis of the bone lesion?

. Brown tumor (Osteitis fibrosa cystica)
. Multiple myeloma
. Giant cell tumor of bone
. Metastatic breast carcinoma
. Aneurysmal bone cyst

Correct Answer & Explanation

. Brown tumor (Osteitis fibrosa cystica)

Explanation

The clinical picture of hypercalcemia, hypophosphatemia, elevated PTH, kidney stones, and a lytic bone lesion describes primary hyperparathyroidism. The bone lesion is a 'brown tumor,' which represents localized osteoclast hyperactivity and marrow fibrosis.

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