10. Pathology and Oncology MCQs

What is the most significant prognostic factor for overall survival in a patient with localized, high-grade intramedullary osteosarcoma of the distal femur following neoadjuvant chemotherapy and surgical resection?

A 25-year-old male presents with a slowly growing, painful mass deep in the thigh. MRI shows a well-circumscribed heterogeneous soft tissue mass adjacent to the femur but not invading the bone. Biopsy reveals a biphasic tumor with both epithelial and spindle cell components. Which of the following genetic translocations is most characteristic of this lesion?

A 12-year-old boy presents with pain and swelling in the midshaft of his tibia. Radiographs demonstrate a permeative, diaphyseal lytic lesion with an 'onion skin' periosteal reaction. Histopathology reveals sheets of small round blue cells. Immunohistochemistry is strongly positive for CD99. What is the most appropriate initial treatment sequence?

A 15-year-old boy reports severe, throbbing right thigh pain that is worse at night and completely relieved by ibuprofen. A CT scan shows a 7-mm radiolucent nidus surrounded by dense sclerotic bone in the femoral diaphysis. What is the primary mediator responsible for the severe pain associated with this lesion?

A 22-year-old male with known multiple hereditary exostoses (MHE) presents with a rapidly enlarging, painful mass over the posterior aspect of his distal femur. An MRI shows an osteochondroma with a cartilage cap thickness of 2.5 cm. Which of the following gene mutations is most strongly associated with his underlying condition?

A 16-year-old female presents with mild knee pain. Radiographs reveal an expansile, eccentric lytic lesion in the proximal tibial metaphysis. MRI demonstrates multiple fluid-fluid levels within the lesion. Biopsy shows blood-filled spaces lacking an endothelial lining. Which genetic rearrangement is considered the primary driver of this lesion?

A 25-year-old man presents with a slowly enlarging, painless mass on the posterior aspect of his distal thigh. Radiographs demonstrate a dense, heavily ossified mass attached to the posterior cortex of the distal femur with a broad base, and a subtle radiolucent line separating a portion of the tumor from the underlying bone (a 'string sign'). Biopsy reveals a spindle cell proliferation with low-grade atypia and well-formed bone trabeculae. Which of the following is the most characteristic genetic alteration associated with this patient's condition?

A 14-year-old boy presents with progressive thigh pain, low-grade fevers, and an elevated erythrocyte sedimentation rate. Radiographs show a permeative diaphyseal lesion in the femur with a multi-layered, 'onion skin' periosteal reaction. Histologic examination of a biopsy specimen reveals sheets of uniform, small, round blue cells that strongly express CD99 on immunohistochemistry. The most common chromosomal translocation associated with this diagnosis results in which of the following fusion genes?

A 16-year-old girl is evaluated for rapid onset of pain and swelling over the distal fibula. Radiographs show an eccentric, expansile, lytic lesion with cortical thinning. An MRI reveals multiple cysts with fluid-fluid levels. Core biopsy is consistent with an aneurysmal bone cyst (ABC). Primary aneurysmal bone cysts are distinct neoplastic entities frequently characterized by a translocation involving which of the following genes?

A 65-year-old man presents to the clinic with severe, unrelenting mid-back pain and progressive fatigue. Laboratory studies reveal hypercalcemia and a normocytic anemia. Plain radiographs demonstrate multiple sharply demarcated, 'punched-out' lytic lesions throughout the calvarium and thoracolumbar spine. Which of the following diagnostic findings is most specific for confirming the primary underlying etiology?

A 30-year-old man notes a slowly growing, deeply seated, painful mass on the plantar aspect of his foot that he first noticed over a year ago. MRI reveals a 4-cm soft-tissue mass with multi-lobular, heterogeneous signal adjacent to the plantar fascia. Biopsy reveals a biphasic tumor consisting of both epithelial-like gland structures and a spindle cell stroma. Which of the following cytogenetic abnormalities is pathognomonic for this tumor?

An 18-year-old man complains of persistent mid-back pain that is worse at night. He reports that the pain is only partially relieved by ibuprofen. A CT scan of the thoracic spine demonstrates a well-circumscribed, 2.8-cm radiolucent nidus in the posterior elements of T12, surrounded by moderate reactive sclerosis. Based on the size and clinical characteristics of the lesion, what is the most likely diagnosis?

A 15-year-old boy presents with a painful, enlarging mass about the right knee. Imaging reveals a mixed lytic and sclerotic lesion in the distal femoral metaphysis with an aggressive periosteal reaction. Biopsy confirms high-grade intramedullary osteosarcoma. Which of the following genetic alterations is most frequently associated with the pathogenesis of this disease?

A 12-year-old boy presents with fever, weight loss, and a painful mass in the diaphysis of the left femur. Radiographs show a permeative lytic lesion with an 'onion-skin' periosteal reaction. A biopsy is performed. Which of the following immunohistochemical markers or genetic findings is most specific to confirm the likely diagnosis?

A 55-year-old man undergoes curettage and bone grafting for an expansile lytic lesion in the proximal phalanx of his ring finger, which has been growing slowly. Histology shows a well-circumscribed cartilaginous tumor with mild cellular atypia. This tumor is most commonly associated with somatic mutations in which of the following genes?