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10. Pathology and Oncology MCQs

Practice Set 290 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 5781

Topic: 10. Pathology and Oncology

A 65-year-old female presents with a pathological fracture of her proximal humerus. Radiographs show multiple punched-out lytic lesions without reactive sclerosis. Laboratory evaluation reveals a monoclonal gammopathy and hypercalcemia. Which of the following is the most appropriate definitive diagnostic test to confirm the underlying disease?

. Bone scan
. Skeletal survey
. Bone marrow biopsy
. Serum protein electrophoresis (SPEP)
. Urine for Bence Jones proteins

Correct Answer & Explanation

. Bone marrow biopsy

Explanation

The patient's presentation is classic for multiple myeloma. While SPEP, UPEP, and a skeletal survey are important parts of the diagnostic workup, the definitive diagnostic test to confirm multiple myeloma is a bone marrow biopsy demonstrating >10% clonal plasma cells.

Question 5782

Topic: 10. Pathology and Oncology

A patient undergoing an elective orthopedic procedure suddenly develops tachycardia, muscle rigidity, and a rapidly rising core temperature following the administration of sevoflurane. Which of the following is the primary defective cellular mechanism responsible for this condition?

. Impaired presynaptic acetylcholine release at the neuromuscular junction
. Defective reuptake of calcium by the sarcoplasmic reticulum ATPase
. Abnormal ryanodine receptor leading to excessive uncontrolled calcium release
. Uncoupling of oxidative phosphorylation in skeletal muscle mitochondria
. Irreversible blockade of postsynaptic sodium channels

Correct Answer & Explanation

. Abnormal ryanodine receptor leading to excessive uncontrolled calcium release

Explanation

Malignant hyperthermia is a life-threatening pharmacogenetic disorder triggered by volatile anesthetics and depolarizing muscle relaxants. It is most commonly caused by an autosomal dominant mutation in the RYR1 gene, which encodes the ryanodine receptor. This leads to massive, uncontrolled release of calcium from the sarcoplasmic reticulum, causing sustained muscle contraction and hypermetabolism.

Question 5783

Topic: 10. Pathology and Oncology

A 15-year-old boy is diagnosed with conventional high-grade osteosarcoma of the distal femur. The pathogenesis of this tumor is most strongly associated with a loss-of-function mutation in which of the following tumor suppressor genes?

. APC
. BRCA1
. PTEN
. TP53
. VHL

Correct Answer & Explanation

. TP53

Explanation

Osteosarcoma pathogenesis is strongly linked to mutations in two critical tumor suppressor genes: TP53 and RB1. Patients with Li-Fraumeni syndrome (germline TP53 mutation) and hereditary retinoblastoma (germline RB1 mutation) are at substantially increased risk of developing osteosarcoma.

Question 5784

Topic: 10. Pathology and Oncology

A 24-year-old male presents with a slow-growing, painful mass near his knee joint. An MRI reveals a soft tissue mass adjacent to, but not within, the joint space. Biopsy demonstrates a biphasic pattern of spindle cells and epithelial cells. Which of the following chromosomal translocations is most characteristic of this lesion?

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

Correct Answer & Explanation

. t(X;18)

Explanation

The clinical and histologic description is classic for a synovial sarcoma, which typically occurs adjacent to joints rather than intra-articularly. The pathognomonic chromosomal translocation is t(X;18)(p11;q11), leading to the SYT-SSX fusion gene. t(11;22) is Ewing sarcoma, t(12;16) is myxoid liposarcoma, and t(2;13) is alveolar rhabdomyosarcoma.

Question 5785

Topic: 10. Pathology and Oncology

A 16-year-old male complains of severe night pain in his proximal femur that is dramatically relieved by ibuprofen. Imaging shows a 1 cm radiolucent nidus surrounded by dense reactive sclerosis. What is the primary biochemical mediator responsible for the intense pain in this condition?

. Leukotriene B4
. Prostaglandin E2
. Interleukin-6
. Tumor Necrosis Factor-alpha
. Substance P

Correct Answer & Explanation

. Prostaglandin E2

Explanation

The classic presentation of an osteoid osteoma includes nocturnal pain relieved by NSAIDs. The nidus contains high concentrations of cyclooxygenase (COX-1 and COX-2) enzymes, leading to massive local production of Prostaglandin E2 (PGE2), which induces the profound pain characteristic of this benign bone tumor.

Question 5786

Topic: 10. Pathology and Oncology

A 16-year-old male is diagnosed with classic high-grade intramedullary osteosarcoma of the distal femur. Which of the following is considered the most significant independent poor prognostic factor for survival at the time of presentation?

. Elevated serum alkaline phosphatase or lactate dehydrogenase
. Location in the distal femur rather than proximal tibia
. Patient age greater than 15 years
. Telangiectatic histologic subtype
. Tumor volume less than 100 mL

Correct Answer & Explanation

. Elevated serum alkaline phosphatase or lactate dehydrogenase

Explanation

Elevated serum alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) levels at presentation correlate with increased tumor burden and a higher rate of metastasis, making them significant poor prognostic indicators in osteosarcoma.

Question 5787

Topic: 10. Pathology and Oncology

Molecular analysis of bone tumors has become critical for accurate diagnosis. Which of the following genetic mutations is most frequently identified in central enchondromas and primary central chondrosarcomas?

. t(11;22) translocation
. IDH1 and IDH2 mutations
. t(X;18) translocation
. MDM2 amplification
. BRAF V600E mutation

Correct Answer & Explanation

. IDH1 and IDH2 mutations

Explanation

Somatic mutations in the isocitrate dehydrogenase genes (IDH1 and IDH2) are found in over 50% of central enchondromas and conventional central chondrosarcomas. These mutations produce an oncometabolite that alters DNA methylation.

Question 5788

Topic: 10. Pathology and Oncology

A 12-year-old girl is diagnosed with a conventional intramedullary osteosarcoma of the distal femur. Her family history is notable for early-onset breast cancer and brain tumors. A genetic workup reveals a germline mutation in the TP53 gene. Which of the following syndromes does she most likely have?

. Retinoblastoma syndrome
. Li-Fraumeni syndrome
. Rothmund-Thomson syndrome
. Beckwith-Wiedemann syndrome
. McCune-Albright syndrome

Correct Answer & Explanation

. Li-Fraumeni syndrome

Explanation

Li-Fraumeni syndrome is an autosomal dominant disorder caused by a germline mutation in the TP53 tumor suppressor gene. It significantly increases the risk of developing osteosarcoma, breast cancer, brain tumors, and soft tissue sarcomas.

Question 5789

Topic: 10. Pathology and Oncology

An 11-year-old boy presents with progressive diaphyseal thigh pain. Radiographs reveal a permeative destructive lesion with an 'onion-skin' periosteal reaction. Biopsy shows small blue round cells. Which of the following chromosomal translocations is most characteristic of this pathology?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is characterized by the t(11;22) translocation in approximately 85% of cases, resulting in the EWS-FLI1 fusion protein. t(X;18) is associated with Synovial sarcoma. t(9;22) can be seen in the Philadelphia chromosome (CML) and some mesenchymal chondrosarcomas. t(2;13) is characteristic of Alveolar rhabdomyosarcoma. t(12;16) is found in Myxoid liposarcoma.

Question 5790

Topic: 10. Pathology and Oncology

Which of the following is considered the most reliable and significant prognostic factor for long-term survival in patients with high-grade conventional osteosarcoma?

. Histologic subtype (e.g., osteoblastic vs. fibroblastic)
. Patient age at diagnosis
. Percentage of tumor necrosis following neoadjuvant chemotherapy
. Presence of a pathologic fracture at presentation
. Alkaline phosphatase level at diagnosis

Correct Answer & Explanation

. Percentage of tumor necrosis following neoadjuvant chemotherapy

Explanation

The percentage of tumor necrosis following neoadjuvant chemotherapy (specifically >90% necrosis representing a 'good responder') is one of the most reliable and significant prognostic indicators for long-term survival in high-grade osteosarcoma.

Question 5791

Topic: Bone Tumors

A 14-year-old boy presents with severe, progressive right groin pain that is distinctly worse at night and dramatically relieved by NSAIDs. Imaging shows a 1cm radiolucent nidus surrounded by reactive sclerosis in the femoral neck. If this untreated lesion is located within the hip joint capsule, which of the following complications is most likely?

. Malignant transformation to osteosarcoma
. Premature closure of the triradiate cartilage
. Early-onset secondary osteoarthritis
. Avascular necrosis of the femoral head
. Pathologic intertrochanteric fracture

Correct Answer & Explanation

. Early-onset secondary osteoarthritis

Explanation

An intra-articular osteoid osteoma (such as in the femoral neck/hip) can cause an intense inflammatory synovitis mediated by high levels of prostaglandins produced by the nidus. Over time, this leads to cartilage degradation and early-onset secondary osteoarthritis.

Question 5792

Topic: 10. Pathology and Oncology

A 24-year-old male presents with a deep, slow-growing soft tissue mass in his thigh. Biopsy reveals a biphasic spindle cell neoplasm. Which of the following chromosomal translocations is most strongly associated with this diagnosis?

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

Correct Answer & Explanation

. t(X;18)

Explanation

The patient has a synovial sarcoma, which is classically associated with the t(X;18) translocation involving the SYT and SSX genes. Ewing sarcoma is associated with t(11;22), and myxoid liposarcoma with t(12;16).

Question 5793

Topic: 10. Pathology and Oncology

A 16-year-old boy presents with knee pain. Radiographs reveal a "sunburst" periosteal reaction in the distal femur. Biopsy confirms malignant spindle cells producing unmineralized osteoid. What is the most significant prognostic factor for overall survival in this patient?

. Serum alkaline phosphatase levels at presentation
. Tumor size at the time of diagnosis
. Histologic response (tumor necrosis percentage) to neoadjuvant chemotherapy
. Presence of a pathologic fracture
. Type of surgical resection (limb salvage vs. amputation)

Correct Answer & Explanation

. Histologic response (tumor necrosis percentage) to neoadjuvant chemotherapy

Explanation

In high-grade osteosarcoma, the degree of tumor necrosis following neoadjuvant chemotherapy (measured by the Huvos grading system) is the single most important prognostic indicator for long-term survival. Greater than 90% necrosis is considered a good response.

Question 5794

Topic: 10. Pathology and Oncology

A 25-year-old male presents with a slow-growing, deep soft-tissue mass near his knee. Biopsy reveals a biphasic pattern consisting of both epithelial and spindle cells. Which chromosomal translocation is specific to this soft-tissue sarcoma?

. t(11;22)(q24;q12)
. t(X;18)(p11;q11)
. t(12;16)(q13;p11)
. t(2;13)(q35;q14)
. t(9;22)(q34;q11)

Correct Answer & Explanation

. t(X;18)(p11;q11)

Explanation

Synovial sarcoma is classically associated with the t(X;18)(p11;q11) chromosomal translocation, which fuses the SYT gene on chromosome 18 with the SSX1 or SSX2 gene on the X chromosome. A biphasic histologic pattern is a classic feature.

Question 5795

Topic: 10. Pathology and Oncology

A 72-year-old man with a long-standing history of increasing hat size and bilateral bowing of his tibiae presents with a newly painful swelling over his proximal humerus. Radiographs show a destructive, permeative lesion with cortical breakthrough. Which of the following is the most likely diagnosis?

. Chondrosarcoma
. Multiple Myeloma
. Secondary Osteosarcoma
. Metastatic Prostate Cancer
. Ewing Sarcoma

Correct Answer & Explanation

. Secondary Osteosarcoma

Explanation

The patient has Paget's disease of bone, characterized by increasing hat size and long bone bowing. A sudden onset of pain and a destructive bone lesion in this demographic strongly suggests secondary osteosarcoma, which has a poor prognosis.

Question 5796

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with a destructive diaphyseal lesion in the femur with a 'periosteal onion-skinning' appearance. Biopsy shows a sheet of uniform small round blue cells. Which chromosomal translocation is most characteristic of this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and radiographic scenario describes Ewing sarcoma. The t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein, is found in approximately 85% of Ewing sarcomas. In contrast, t(X;18) is seen in Synovial Sarcoma, t(12;16) in Myxoid Liposarcoma, t(9;22) in CML/Chondrosarcoma variants, and t(2;13) in Alveolar Rhabdomyosarcoma.

Question 5797

Topic: 10. Pathology and Oncology

A 65-year-old male with a history of renal cell carcinoma presents with a large, destructive lytic lesion in his proximal femur. He is scheduled for prophylactic intramedullary nailing. What is the most critical preoperative step prior to the surgical stabilization of this specific metastasis?

. Administration of denosumab
. Radiation therapy to the entire femur
. Preoperative embolization of the tumor bed
. Administration of intravenous bisphosphonates
. Open incisional biopsy of the lesion

Correct Answer & Explanation

. Preoperative embolization of the tumor bed

Explanation

Renal cell carcinoma and thyroid carcinoma metastases are notoriously hypervascular. Preoperative selective arterial embolization is critically indicated to minimize massive, potentially life-threatening intraoperative blood loss.

Question 5798

Topic: Bone Tumors

A 65-year-old male presents with a pathologic fracture of the proximal humerus. Subsequent systemic workup reveals hypercalcemia, normocytic anemia, and Bence-Jones proteinuria. What is the characteristic radiographic appearance of the skeletal lesions associated with this pathology?

. Blastic lesions associated with a sunburst periosteal reaction
. Expansile, multiloculated lytic lesions with prominent internal septations
. Punched-out lytic lesions with a complete absence of surrounding reactive sclerosis
. A metaphyseal lytic lesion complicated by a classic Codman triangle
. Homogeneously dense, sclerotic ivory vertebrae

Correct Answer & Explanation

. Punched-out lytic lesions with a complete absence of surrounding reactive sclerosis

Explanation

The clinical picture is diagnostic for multiple myeloma, the most common primary malignancy of bone in adults. Radiographically, multiple myeloma typically presents with distinctive "punched-out" lytic bone lesions that conspicuously lack any reactive sclerotic rim due to severe osteoblast inhibition.

Question 5799

Topic: 10. Pathology and Oncology

A 15-year-old boy undergoes neoadjuvant chemotherapy followed by wide resection for a distal femur osteosarcoma. Which of the following is the most important prognostic factor for long-term survival in this patient?

. Initial tumor volume
. Anatomical location of the tumor
. Patient age at presentation
. Percentage of tumor necrosis on the resected specimen
. Histologic subtype of the tumor

Correct Answer & Explanation

. Percentage of tumor necrosis on the resected specimen

Explanation

The histologic response to neoadjuvant chemotherapy is the single most important prognostic indicator for long-term survival in osteosarcoma. Greater than 90% tumor necrosis in the resected specimen defines a good responder and portends a better prognosis.

Question 5800

Topic: 10. Pathology and Oncology

A 32-year-old woman presents with knee pain. Radiographs reveal an eccentric, lytic epiphyseal lesion extending to the subchondral bone of the proximal tibia. Biopsy confirms a Giant Cell Tumor of bone. What is the most widely accepted surgical treatment?

. Wide en bloc resection and endoprosthetic reconstruction
. Extended intralesional curettage with high-speed burring and local adjuvants
. Radiation therapy alone
. Chemotherapy followed by marginal excision
. Above-knee amputation

Correct Answer & Explanation

. Extended intralesional curettage with high-speed burring and local adjuvants

Explanation

Giant cell tumors are locally aggressive, benign bone tumors. The standard of care is extended intralesional curettage utilizing a high-speed burr along with local adjuvants (e.g., phenol, liquid nitrogen, or PMMA cement) to minimize the risk of local recurrence.

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