10. Pathology and Oncology MCQs

A 25-year-old female presents with a slowly enlarging mass on the posterior aspect of her knee. Radiographs reveal a dense, heavily ossified mass arising from the posterior distal femur with a radiolucent cleft separating the tumor from the underlying cortex (string sign). What is the most likely diagnosis?

Neoadjuvant chemotherapy has significantly improved survival rates in patients with conventional high-grade osteosarcoma. Which of the following regimens represents the standard first-line combination therapy?

A 15-year-old male presents with severe pain in his distal femur. Radiographs show a destructive, expansile lytic lesion. MRI demonstrates multiple fluid-fluid levels. Core needle biopsy shows blood-filled spaces lined by malignant cells producing delicate lace-like osteoid. What is the diagnosis?

A 70-year-old male with a 20-year history of Paget's disease of bone develops acute, severe pain and rapid swelling in his right proximal femur. Radiographs show a new destructive lytic lesion with cortical breakthrough. What is the most likely etiology?

A 45-year-old female complains of chronic, painless swelling in her right knee. MRI reveals a diffuse, frond-like synovial mass that is hyperintense on T1-weighted images and demonstrates complete signal loss on fat-suppressed sequences. What is the most likely diagnosis?

A 35-year-old male with Hereditary Multiple Exostoses (HME) reports an enlarging, painful mass in his pelvis over the last 6 months.

Which of the following MRI features is the most reliable indicator of malignant transformation to a secondary chondrosarcoma?

A 20-year-old female presents with a palpable mass on the anterior midshaft of her tibia. Radiographs show a broad-based surface lesion with a sunburst 'hair-on-end' periosteal reaction. There is no medullary involvement. Biopsy reveals an intermediate-grade chondroblastic matrix. What is the diagnosis?

A 55-year-old male presents with a painless, slow-growing, subcutaneous mass on his posterior neck. Excisional biopsy histology reveals mature adipocytes admixed with uniform spindle cells and thick ropey collagen bundles. Immunohistochemistry is strongly positive for CD34. What is the correct diagnosis?

When evaluating a newly diagnosed patient with conventional high-grade osteosarcoma, what is the most significant independent prognostic factor for long-term overall survival?

An incisional biopsy is planned for a suspected high-grade osteosarcoma of the distal femur. To avoid compromising the definitive limb-salvage surgery, which of the following oncologic biopsy principles must be strictly adhered to?

Atypical Lipomatous Tumors (ALTs) and Well-Differentiated Liposarcomas (WDLPS) share identical histologic features and MDM2 amplification. The designation WDLPS is specifically reserved for tumors occurring in which anatomic location due to their inherent risk of lethal local progression?

A 16-year-old male presents with knee pain, and radiographs reveal a mixed lytic/sclerotic metaphyseal lesion highly suspicious for osteosarcoma.

To adequately plan the level of surgical resection, which imaging modality is mandatory to evaluate for intramedullary skip metastases?

A 55-year-old male undergoes a marginal 'shell-out' excision of a deep, intermuscular thigh mass presumed to be a simple lipoma. Final pathology reveals an Atypical Lipomatous Tumor (ALT) with positive microscopic margins but no dedifferentiation. What is the expected clinical behavior if only observation is pursued?

A 14-year-old boy presents with progressive, non-mechanical knee pain. Radiographs demonstrate a mixed sclerotic and lytic lesion in the distal femoral metaphysis with a Codman's triangle and sunburst periosteal reaction. Which of the following MRI sequences is most critical for surgical planning of the resection?

A 24-year-old female presents with a painless mass at the posterior aspect of her distal thigh. Radiographs demonstrate a heavily ossified mass arising from the posterior cortex of the distal femur. Biopsy reveals low-grade spindle cells with woven bone. What is the most common genetic abnormality associated with this tumor?

A 15-year-old boy with conventional high-grade osteosarcoma of the proximal tibia is undergoing neoadjuvant MAP chemotherapy (Methotrexate, Doxorubicin, Cisplatin). He suddenly develops dyspnea and bilateral lower extremity edema. Echocardiography shows a severely reduced ejection fraction. Which chemotherapeutic agent is most likely responsible for this complication?

A 16-year-old female presents with acute thigh pain following a minor fall. Radiographs show an aggressive, purely lytic lesion in the distal femoral metaphysis with a pathologic fracture. MRI shows fluid-fluid levels throughout the lesion. Biopsy reveals blood-filled spaces with highly pleomorphic, atypical, malignant spindle cells in the septa producing osteoid. What is the diagnosis?

A 72-year-old male with a long-standing history of Paget's disease of bone presents with rapidly worsening pain and swelling in his right humerus. Radiographs show a new area of cortical destruction and a soft tissue mass. Biopsy confirms high-grade osteosarcoma. Which of the following best describes the prognosis of this patient compared to a pediatric patient with primary conventional osteosarcoma?