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10. Pathology and Oncology MCQs

Practice Set 94 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 1861

Topic: 10. Pathology and Oncology

A 55-year-old woman is diagnosed with a grade II chondrosarcoma of the ilium. Staging studies show no evidence of metastatic disease. What is the most appropriate definitive management?

. Intralesional curettage and bone grafting
. Preoperative radiation followed by wide resection
. Neoadjuvant chemotherapy followed by wide resection
. Wide surgical resection alone
. Definitive radiation therapy

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Intermediate and high-grade chondrosarcomas are notoriously resistant to both chemotherapy and radiation therapy. The standard of care is wide surgical resection with negative margins.

Question 1862

Topic: 10. Pathology and Oncology

A 40-year-old man presents with chronic hip pain. Radiographs reveal an epiphyseal lytic lesion in the proximal femur with central calcifications. Biopsy demonstrates sheets of cells with abundant clear cytoplasm and distinct boundaries mixed with areas of hyaline cartilage. What is the most likely diagnosis?

. Chondroblastoma
. Clear cell chondrosarcoma
. Osteoblastoma
. Giant cell tumor
. Aneurysmal bone cyst

Correct Answer & Explanation

. Clear cell chondrosarcoma

Explanation

Clear cell chondrosarcoma is a rare, low-grade malignant bone tumor that characteristically involves the epiphysis of long bones in middle-aged adults. It must be differentiated from chondroblastoma, which typically occurs in much younger patients with open physes.

Question 1863

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with a diaphysial permeative lesion in the fibula with an associated "onion-skin" periosteal reaction. A core needle biopsy is performed. Which of the following immunohistochemical markers and translocations will most likely be positive?

. CD99; t(11;22)
. S100; t(X;18)
. Vimentin; t(12;16)
. Cytokeratin; t(2;13)
. Desmin; t(9;22)

Correct Answer & Explanation

. CD99; t(11;22)

Explanation

Ewing sarcoma typically presents with a permeative diaphyseal lesion and "onion-skinning". It is strongly positive for CD99 (MIC2) and is characterized by the t(11;22) translocation, forming the EWS-FLI1 fusion protein.

Question 1864

Topic: Bone Tumors

A 16-year-old boy has night pain in his tibia relieved by NSAIDs. CT shows a 6 mm radiolucent nidus surrounded by sclerotic bone. Radiofrequency ablation (RFA) is planned. RFA is contraindicated if the lesion is located within what distance of a major motor nerve?

. 1 mm
. 5 mm
. 10 mm
. 15 mm
. 20 mm

Correct Answer & Explanation

. 10 mm

Explanation

Radiofrequency ablation is the treatment of choice for most osteoid osteomas. However, it is generally contraindicated if the nidus is located within 1 cm (10 mm) of a major nerve or the spinal cord to avoid thermal neural injury.

Question 1865

Topic: 10. Pathology and Oncology

A 68-year-old man presents with diffuse bone pain and a newly diagnosed pathologic fracture of the proximal humerus. Laboratory studies reveal hypercalcemia, anemia, and renal insufficiency. Serum protein electrophoresis shows an M-spike. Which of the following is the most definitive diagnostic test for his underlying condition?

. Bone scan
. Skeletal survey
. Bone marrow biopsy
. Urine immunofixation
. MRI of the entire spine

Correct Answer & Explanation

. Bone marrow biopsy

Explanation

The patient's clinical picture is classic for multiple myeloma (CRAB criteria). A bone marrow biopsy demonstrating greater than 10% clonal plasma cells is required for definitive diagnosis.

Question 1866

Topic: 10. Pathology and Oncology

A 55-year-old man undergoes resection of a large, deep soft tissue mass in his posterior thigh. Pathology reveals a myxoid liposarcoma. Which of the following genetic translocations is characteristic of this tumor?

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

Correct Answer & Explanation

. t(12;16)

Explanation

Myxoid liposarcoma is characterized by the t(12;16) translocation, which results in the FUS-DDIT3 fusion gene. It frequently metastasizes to extrapulmonary sites, such as the spine and other bones.

Question 1867

Topic: 10. Pathology and Oncology

A 30-year-old woman presents with a firm, painless mass in the anterior thigh. Biopsy demonstrates a proliferation of bland fibroblastic cells in a collagenous stroma with no atypia or necrosis. Beta-catenin staining is strongly positive. Which of the following is the most appropriate initial management?

. Wide surgical excision
. Observation and conservative management
. Neoadjuvant chemotherapy
. Radiation therapy
. Amputation

Correct Answer & Explanation

. Observation and conservative management

Explanation

The pathology describes a desmoid tumor (aggressive fibromatosis), characterized by beta-catenin mutations. Current guidelines strongly favor initial observation (active surveillance) as many tumors spontaneously stabilize or regress.

Question 1868

Topic: 10. Pathology and Oncology

A 35-year-old man presents with anterior tibial pain. Radiographs show a multiloculated, eccentric, osteolytic lesion in the anterior tibial diaphysis. Histology shows nests of epithelial cells in a fibrous stroma. What is the recommended treatment?

. Curettage and bone grafting
. Wide surgical resection
. Radiation therapy
. Chemotherapy followed by curettage
. Amputation

Correct Answer & Explanation

. Wide surgical resection

Explanation

The clinical and histologic picture describes adamantinoma, a low-grade malignant bone tumor that almost exclusively occurs in the anterior tibial diaphysis. It is insensitive to radiation and chemotherapy, making wide surgical resection the treatment of choice.

Question 1869

Topic: 10. Pathology and Oncology

A 45-year-old patient with Neurofibromatosis type 1 (NF1) notices rapid enlargement and pain in a long-standing peripheral nerve mass. Biopsy reveals a high-grade spindle cell sarcoma. Which genetic alteration is most closely associated with the underlying syndrome leading to this tumor?

. Mutation of the TP53 gene
. Mutation in the NF1 gene resulting in loss of neurofibromin
. t(11;22) translocation
. Amplification of MDM2
. Beta-catenin gene mutation

Correct Answer & Explanation

. Mutation in the NF1 gene resulting in loss of neurofibromin

Explanation

Patients with NF1 have a mutation in the NF1 gene, leading to a loss of the tumor suppressor protein neurofibromin. They have a 5-10% lifetime risk of developing a Malignant Peripheral Nerve Sheath Tumor (MPNST), often from a pre-existing plexiform neurofibroma.

Question 1870

Topic: 10. Pathology and Oncology

A 72-year-old man with a long-standing history of Paget's disease of the pelvis presents with increasing pain and a rapidly enlarging mass in the right ilium. Radiographs show a new area of aggressive cortical destruction. What is the most likely diagnosis?

. Metastatic prostate cancer
. Secondary osteosarcoma
. Chondrosarcoma
. Ewing sarcoma
. Multiple myeloma

Correct Answer & Explanation

. Secondary osteosarcoma

Explanation

Secondary osteosarcoma is a rare but highly lethal complication of Paget's disease, occurring in approximately 1% of patients. It presents with new-onset, severe pain and rapidly progressive bone destruction in an area of previously stable pagetic bone.

Question 1871

Topic: 10. Pathology and Oncology

Which of the following is a fundamental principle when performing a biopsy of a suspected malignant musculoskeletal tumor?

. The biopsy tract should be placed transversely across the extremity
. The biopsy should routinely include draining lymph nodes
. The biopsy tract must be planned so it can be completely excised during definitive resection
. A tourniquet should be inflated and deflated before the incision is closed
. Extensive subfascial flaps should be raised to optimize visualization

Correct Answer & Explanation

. The biopsy tract must be planned so it can be completely excised during definitive resection

Explanation

Biopsy tracts are considered contaminated with tumor cells. A core principle of oncologic surgery is placing the biopsy incision longitudinally and in line with the planned definitive surgical incision so the entire tract can be excised en bloc.

Question 1872

Topic: 10. Pathology and Oncology

A 35-year-old woman presents with recurrent, bloody knee effusions and joint pain. MRI reveals a large, lobulated intra-articular mass with prominent "blooming" artifact on gradient-echo sequences. What is the primary pathophysiologic driver of this condition?

. Overexpression of colony-stimulating factor 1 (CSF1)
. Mutation in the EXT1 gene
. SYT-SSX fusion protein
. Loss of retinoblastoma (Rb) protein function
. Overexpression of HER2/neu

Correct Answer & Explanation

. Overexpression of colony-stimulating factor 1 (CSF1)

Explanation

The patient has diffuse tenosynovial giant cell tumor (formerly PVNS), characterized by a blooming artifact on MRI due to hemosiderin. The underlying pathogenesis involves a translocation leading to the overexpression of CSF1, which recruits the macrophages that form the tumor mass.

Question 1873

Topic: 10. Pathology and Oncology

A 60-year-old woman with breast cancer has a lytic metastasis in the peritrochanteric region of the femur. The lesion involves 50% of the cortex, and she reports moderate pain with weight-bearing. Using Mirels' criteria, what is her score and the recommended management?

. Score 7; observation and radiation
. Score 8; observation and bisphosphonates
. Score 10; prophylactic internal fixation
. Score 12; amputation
. Score 6; chemotherapy alone

Correct Answer & Explanation

. Score 10; prophylactic internal fixation

Explanation

Mirels' criteria assess fracture risk based on site (lower extremity = 3), pain (moderate = 2), lesion type (lytic = 3), and size (1/3 to 2/3 cortex = 2), totaling 10. A score of 9 or higher warrants prophylactic internal fixation.

Question 1874

Topic: 10. Pathology and Oncology

A 25-year-old male presents with chronic knee pain. Imaging reveals a lytic lesion in the proximal tibial epiphysis. Biopsy shows chondroid matrix with cells containing abundant clear cytoplasm. Immunohistochemistry is positive for S-100. What is the most likely diagnosis?

. Chondroblastoma
. Clear cell chondrosarcoma
. Giant cell tumor of bone
. Osteosarcoma
. Chondromyxoid fibroma

Correct Answer & Explanation

. Clear cell chondrosarcoma

Explanation

Clear cell chondrosarcoma is a low-grade malignant bone tumor that typically arises in the epiphysis of long bones in young adults. Histologically, it is characterized by cells with abundant clear cytoplasm and chondroid matrix, distinguishing it from chondroblastoma and giant cell tumors.

Question 1875

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with thigh pain. Radiographs show a sunburst periosteal reaction in the distal femur. Biopsy confirms osteosarcoma. Following neoadjuvant chemotherapy, what is the most important prognostic factor for his overall survival?

. Initial tumor volume
. Specific histologic subtype
. Percentage of tumor necrosis
. Initial alkaline phosphatase level
. Surgical margin width > 2 cm

Correct Answer & Explanation

. Percentage of tumor necrosis

Explanation

The most significant prognostic factor for overall survival in patients with osteosarcoma is the percentage of tumor necrosis following neoadjuvant chemotherapy. A necrosis rate of 90% or greater is considered a favorable histologic response.

Question 1876

Topic: 10. Pathology and Oncology

A 35-year-old male presents with a deep thigh mass. Biopsy reveals a biphasic spindle cell neoplasm. Molecular testing shows a t(X;18) translocation. Which of the following is the most likely diagnosis?

. Synovial sarcoma
. Clear cell sarcoma
. Myxoid liposarcoma
. Ewing sarcoma
. Alveolar soft part sarcoma

Correct Answer & Explanation

. Synovial sarcoma

Explanation

Synovial sarcoma typically occurs in young adults as a deep soft tissue mass and often displays a biphasic histology. It is genetically characterized by the t(X;18) translocation, resulting in the SYT-SSX fusion gene.

Question 1877

Topic: 10. Pathology and Oncology

A 60-year-old male presents with a pathologic fracture of the proximal humerus. Radiographs show a permeative lytic lesion. Biopsy reveals metastatic renal cell carcinoma. What is the most appropriate next step prior to operative stabilization?

. Neoadjuvant chemotherapy
. Preoperative radiation therapy
. Preoperative angiographic embolization
. Administration of denosumab
. Systemic immunotherapy

Correct Answer & Explanation

. Preoperative angiographic embolization

Explanation

Metastatic renal cell carcinoma and thyroid carcinoma lesions are notoriously hypervascular. Preoperative angiographic embolization is highly recommended to significantly reduce intraoperative blood loss during surgical stabilization.

Question 1878

Topic: Bone Tumors

A 15-year-old male presents with night pain in his tibia that is relieved by NSAIDs. Radiographs show a small radiolucent nidus surrounded by dense sclerotic bone. Which inflammatory mediator is found in high concentrations within the nidus?

. Interleukin-1
. Tumor necrosis factor-alpha
. Prostaglandin E2
. Leukotriene B4
. Histamine

Correct Answer & Explanation

. Prostaglandin E2

Explanation

Osteoid osteomas secrete high levels of prostaglandins, specifically Prostaglandin E2, which causes the characteristic intense night pain. This is the mechanism by which NSAIDs provide dramatic pain relief.

Question 1879

Topic: 10. Pathology and Oncology

A 30-year-old male presents with an anterior tibial bowing deformity and an intracortical lytic lesion in the tibial diaphysis. Biopsy reveals a biphasic tumor with epithelial cells in a fibrous stroma. What is the recommended treatment?

. Intralesional curettage and bone grafting
. Wide surgical resection
. Primary radiation therapy
. Chemotherapy followed by curettage
. Radiofrequency ablation

Correct Answer & Explanation

. Wide surgical resection

Explanation

The clinical and histologic description is classic for adamantinoma, a low-grade malignant bone tumor predominantly affecting the tibial diaphysis. Treatment requires wide surgical resection, as the tumor does not respond well to chemotherapy or radiation.

Question 1880

Topic: 10. Pathology and Oncology

A 16-year-old girl presents with knee pain. Imaging reveals an eccentric, lytic lesion in the distal femoral epiphysis with fine calcifications. Biopsy demonstrates mononuclear cells, scattered osteoclast-like giant cells, and areas of chicken-wire calcification. What is the most likely diagnosis?

. Giant cell tumor of bone
. Clear cell chondrosarcoma
. Chondroblastoma
. Osteosarcoma
. Aneurysmal bone cyst

Correct Answer & Explanation

. Chondroblastoma

Explanation

Chondroblastoma is a benign cartilage tumor that almost exclusively occurs in the epiphysis of skeletally immature patients. Histology is characterized by mononuclear cells, giant cells, and intercellular chicken-wire calcification.

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