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10. Pathology and Oncology MCQs

Practice Set 293 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 5841

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with a painful mass around his distal femur. Radiographs show a destructive, mixed lytic and sclerotic lesion in the metaphysis with a "sunburst" periosteal reaction and a Codman triangle. Biopsy confirms the most likely diagnosis. Which of the following histologic findings is required for this diagnosis?

. Small round blue cells with Homer-Wright rosettes
. Production of osteoid by malignant mesenchymal cells
. Lobules of malignant hyaline cartilage
. Multinucleated giant cells in a background of mononuclear stromal cells
. Sheets of uniform plasma cells with eccentric nuclei

Correct Answer & Explanation

. Production of osteoid by malignant mesenchymal cells

Explanation

Correct Answer: Production of osteoid by malignant mesenchymal cellsThe clinical and radiographic presentation is classic for conventional osteosarcoma. The defining histologic feature required for the diagnosis of osteosarcoma is the production of osteoid (unmineralized bone matrix) directly by malignant mesenchymal cells. Small round blue cells are characteristic of Ewing sarcoma, malignant cartilage is seen in chondrosarcoma, and giant cells are the hallmark of Giant Cell Tumor of bone.

Question 5842

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful, swollen distal femur. Radiographs reveal a destructive metaphyseal lesion with a "sunburst" periosteal reaction. Biopsy confirms high-grade intramedullary osteosarcoma. A germline mutation in which of the following tumor suppressor genes is most classically associated with a hereditary predisposition to this malignancy?

. APC
. BRCA1
. RB1
. NF1
. PTEN

Correct Answer & Explanation

. RB1

Explanation

Correct Answer: RB1Osteosarcoma is the most common primary malignant bone tumor in children and adolescents. While most cases are sporadic, there are well-known genetic predispositions. A germline mutation in the RB1 (retinoblastoma) tumor suppressor gene is classically associated with hereditary retinoblastoma, and these patients have a significantly increased risk (up to 500-fold) of developing secondary malignancies, most notably osteosarcoma. Another critical genetic association is the TP53 mutation, seen in Li-Fraumeni syndrome, which also heavily predisposes individuals to osteosarcoma.

Question 5843

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with progressive knee pain. Radiographs reveal a mixed lytic and sclerotic lesion in the distal femoral metaphysis with a Codman triangle and 'sunburst' periosteal reaction. Core needle biopsy confirms high-grade osteosarcoma. What is the standard of care for definitive treatment?

. Surgical resection alone
. Radiation therapy followed by surgical resection
. Neoadjuvant chemotherapy, surgical resection, and adjuvant chemotherapy
. Primary amputation
. Adjuvant denosumab and intralesional curettage

Correct Answer & Explanation

. Neoadjuvant chemotherapy, surgical resection, and adjuvant chemotherapy

Explanation

The standard of care for high-grade osteosarcoma is multi-agent neoadjuvant chemotherapy, followed by wide surgical resection, and subsequent adjuvant chemotherapy. Osteosarcoma is generally radioresistant.

Question 5844

Topic: 10. Pathology and Oncology

A 14-year-old male presents with severe thigh pain and a large soft tissue mass. Radiographs show a permeative lytic lesion in the femoral diaphysis with an "onion skin" periosteal reaction. Biopsy reveals small blue round cells. Which of the following chromosomal translocations is most characteristic of this diagnosis?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical presentation and histology are classic for Ewing sarcoma. This malignant bone tumor is most commonly associated with the t(11;22) chromosomal translocation, which results in the oncogenic EWS-FLI1 fusion protein.

Question 5845

Topic: 10. Pathology and Oncology

A 32-year-old male presents with a slowly enlarging, painless mass deep in his right thigh. Imaging reveals a calcified soft tissue mass near the knee joint but not communicating with the synovium. A core needle biopsy demonstrates a biphasic spindle cell neoplasm. Which of the following chromosomal translocations 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(X;18)

Explanation

The patient has a synovial sarcoma, which frequently presents as a calcified mass near a joint in a young adult and exhibits a biphasic or monophasic histology. The characteristic genetic abnormality is the t(X;18) translocation, leading to the SYT-SSX fusion gene.

Question 5846

Topic: 10. Pathology and Oncology



A 14-year-old boy presents with progressively worsening thigh pain and low-grade fevers. Imaging reveals a permeative diaphyseal lesion with an "onion-skin" periosteal reaction. Biopsy demonstrates sheets of small round blue cells. Which chromosomal translocation is most characteristically associated with this pathology?

. t(X;18) SYT-SSX
. t(11;22) EWS-FLI1
. t(12;16) FUS-DDIT3
. t(9;22) BCR-ABL
. t(2;13) PAX3-FOXO1

Correct Answer & Explanation

. t(11;22) EWS-FLI1

Explanation

The clinical and radiographic presentation, along with small round blue cells, is diagnostic of Ewing Sarcoma. Over 90% of Ewing sarcomas are characterized by the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein.

Question 5847

Topic: 10. Pathology and Oncology

A 55-year-old man presents with a painful, enlarging mass in his right hemipelvis. Biopsy confirms dedifferentiated chondrosarcoma. Staging scans are negative for metastasis. What is the mainstay of definitive treatment for this lesion?

. Neoadjuvant chemotherapy followed by limb-sparing surgery
. External beam radiation therapy alone
. Wide surgical resection
. Radiofrequency ablation
. Intralesional curettage and cementation

Correct Answer & Explanation

. Wide surgical resection

Explanation

Chondrosarcomas are generally resistant to both chemotherapy and radiation therapy. The primary and most effective treatment for localized, high-grade or dedifferentiated chondrosarcoma is wide surgical resection with negative margins.

Question 5848

Topic: 10. Pathology and Oncology



A 12-year-old girl is diagnosed with the bone tumor seen in the provided radiograph, characterized histologically by Homer-Wright rosettes and a strong PAS-positive reaction. Which immunohistochemical surface marker is characteristically highly expressed in this tumor?

. S-100
. Desmin
. CD99
. Cytokeratin
. MyoD1

Correct Answer & Explanation

. CD99

Explanation

Ewing sarcoma characteristically demonstrates strong, diffuse membranous staining for CD99 (MIC2). S-100 is for neural/melanocytic tumors, and Desmin/MyoD1 are for muscle-derived tumors like rhabdomyosarcoma.

Question 5849

Topic: 10. Pathology and Oncology

Which of the following primary malignant bone tumors is classically associated with mutations in the retinoblastoma (RB1) gene and the TP53 gene?

. Chondrosarcoma
. Osteosarcoma
. Ewing Sarcoma
. Chordoma
. Multiple Myeloma

Correct Answer & Explanation

. Osteosarcoma

Explanation

Osteosarcoma has a strong genetic association with mutations in the RB1 gene (hereditary retinoblastoma) and the TP53 gene (Li-Fraumeni syndrome). Both conditions drastically increase the risk of developing osteosarcoma.

Question 5850

Topic: 10. Pathology and Oncology



A 15-year-old male is diagnosed with Ewing sarcoma of the proximal fibula, as suggested by the aggressive periosteal reaction in the provided radiograph. Which of the following best outlines the standard modern treatment protocol for localized Ewing sarcoma?

. Wide surgical excision alone
. Definitive external beam radiation therapy alone
. Neoadjuvant chemotherapy, local control (surgery/radiation), and adjuvant chemotherapy
. Immediate amputation followed by radiation therapy
. Curettage, cementation, and systemic bisphosphonates

Correct Answer & Explanation

. Neoadjuvant chemotherapy, local control (surgery/radiation), and adjuvant chemotherapy

Explanation

Ewing sarcoma is a systemic disease at presentation even if metastases are not clinically evident. Standard treatment mandates multidrug neoadjuvant chemotherapy, followed by local control (wide surgical resection and/or radiation), and then adjuvant chemotherapy.

Question 5851

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with severe thigh pain, swelling, and low-grade fever. Radiograph shows a permeative diaphyseal lesion with an 'onion-skin' periosteal reaction. Which chromosomal translocation is most characteristically associated with this pathology?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and radiographic presentation is classic for Ewing's sarcoma. It is characterized by the t(11;22) chromosomal translocation, which results in the EWSR1-FLI1 fusion protein in over 85% of cases.

Question 5852

Topic: 10. Pathology and Oncology

Which of the following is the most significant adverse prognostic factor for overall survival in a patient with conventional high-grade osteosarcoma?

. Tumor size greater than 8 cm
. Proximal extremity location
. Poor histologic response to neoadjuvant chemotherapy
. Elevated serum alkaline phosphatase at diagnosis
. Presence of a pathologic fracture

Correct Answer & Explanation

. Poor histologic response to neoadjuvant chemotherapy

Explanation

The percentage of tumor necrosis (histologic response) following neoadjuvant chemotherapy is the most critical prognostic factor for overall survival in osteosarcoma. Less than 90% necrosis indicates a poor response and a worse prognosis.

Question 5853

Topic: 10. Pathology and Oncology
A 60-year-old man presents with a painful shoulder. Radiographs reveal a large destructive lesion in the proximal humerus with 'ring and arc' calcifications. Biopsy confirms a grade II chondrosarcoma. What is the optimal treatment?
. Intralesional curettage and bone grafting
. Wide surgical resection
. Neoadjuvant chemotherapy followed by wide resection
. Primary radiation therapy
. Radiofrequency ablation

Correct Answer & Explanation

. Wide surgical resection

Explanation

Intermediate and high-grade (Grade II and III) chondrosarcomas are notoriously resistant to both chemotherapy and radiation. The standard of care is wide surgical resection with negative margins to prevent local recurrence and metastasis.

Question 5854

Topic: 10. Pathology and Oncology

A 14-year-old presents with a destructive diaphyseal femur lesion. Biopsy reveals sheets of small round blue cells. Which immunohistochemical marker is highly sensitive and typically strongly positive in this tumor?

. S-100
. CD99 (MIC2)
. Cytokeratin
. MyoD1
. Desmin

Correct Answer & Explanation

. CD99 (MIC2)

Explanation

Ewing's sarcoma is a classic small round blue cell tumor that strongly and diffusely expresses CD99 (MIC2) on immunohistochemistry. This marker, along with molecular testing for EWSR1 translocations, confirms the diagnosis.

Question 5855

Topic: Bone Tumors

A 16-year-old boy presents with nocturnal thigh pain that is dramatically relieved by NSAIDs. Imaging reveals a 7mm radiolucent nidus surrounded by dense sclerosis in the femoral diaphysis. What is the biochemical basis for the profound pain relief with NSAIDs?

. The nidus produces high levels of Prostaglandin E2 (PGE2) which NSAIDs inhibit
. NSAIDs shrink the highly vascular nidus
. NSAIDs directly reduce periosteal reaction
. The nidus expresses high levels of COX-1 only
. NSAIDs induce apoptosis of the osteoblastic tumor cells

Correct Answer & Explanation

. The nidus produces high levels of Prostaglandin E2 (PGE2) which NSAIDs inhibit

Explanation

The classic night pain of an osteoid osteoma is mediated by extremely high levels of prostaglandins (specifically PGE2) produced by the nidus. NSAIDs inhibit cyclooxygenase (COX), drastically reducing PGE2 production and providing profound pain relief.

Question 5856

Topic: 10. Pathology and Oncology

Differentiating an active enchondroma from a low-grade (Grade I) chondrosarcoma can be challenging. Which of the following radiographic features is most suggestive of a low-grade chondrosarcoma rather than a benign enchondroma?

. Intralesional popcorn calcification
. Location in the small bones of the hand
. Deep endosteal scalloping greater than two-thirds of the cortical thickness
. Lesion size of 2 cm
. Absence of cortical expansion

Correct Answer & Explanation

. Deep endosteal scalloping greater than two-thirds of the cortical thickness

Explanation

Deep endosteal scalloping (greater than 2/3 of the cortical depth), cortical thickening, increasing pain, and lesion size >5 cm are hallmark signs suggestive of malignant transformation or a low-grade chondrosarcoma over a benign enchondroma.

Question 5857

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a 2-month history of thigh pain. Radiographs show a permeative diaphyseal lesion with an 'onion-skin' periosteal reaction. Biopsy is performed.

Which of the following chromosomal translocations is most characteristic of this diagnosis?

. t(11;22) EWS-FLI1
. t(X;18) SYT-SSX
. t(2;13) PAX3-FKHR
. t(12;16) FUS-CHOP
. t(9;22) BCR-ABL

Correct Answer & Explanation

. t(11;22) EWS-FLI1

Explanation

Ewing sarcoma typically presents as a permeative diaphyseal lesion with an 'onion-skin' periosteal reaction. It is characterized genetically by the t(11;22) translocation resulting in the EWS-FLI1 fusion protein in over 85% of cases.

Question 5858

Topic: 10. Pathology and Oncology

A 12-year-old male is diagnosed with Ewing sarcoma of the pelvis.

Which of the following represents the most significant adverse prognostic factor for this patient?

. Age less than 15 years
. Tumor size less than 8 cm
. Presence of distant metastases at presentation
. Distal extremity involvement
. Male gender

Correct Answer & Explanation

. Presence of distant metastases at presentation

Explanation

The most significant adverse prognostic factor in Ewing sarcoma is the presence of distant metastases at the time of diagnosis. A pelvic location and large tumor size are also considered poor prognostic indicators compared to distal extremity lesions.

Question 5859

Topic: Bone Tumors

A 16-year-old male presents with deep nocturnal aching in his proximal tibia that is dramatically relieved by ibuprofen. Radiographs show localized cortical thickening with a small 5mm radiolucent nidus. What is the primary mechanism by which the pharmacologic agent provides pain relief in this condition?

. Inhibition of osteoclast activity
. Inhibition of cyclooxygenase and decreasing prostaglandin E2 levels
. Selective blockade of mu-opioid receptors
. Reduction of local histamine release
. Direct inhibition of substance P in the dorsal root ganglion

Correct Answer & Explanation

. Inhibition of cyclooxygenase and decreasing prostaglandin E2 levels

Explanation

Osteoid osteomas produce high levels of prostaglandins (specifically PGE2) within the nidus, which cause the characteristic nocturnal pain. NSAIDs provide dramatic relief by inhibiting cyclooxygenase and decreasing local prostaglandin synthesis.

Question 5860

Topic: 10. Pathology and Oncology

A 15-year-old boy completes neoadjuvant chemotherapy for a conventional osteosarcoma of the distal femur and subsequently undergoes wide local excision. Histopathologic analysis of the resected specimen shows 95% tumor necrosis. What is the clinical significance of this finding?

. It indicates a poor prognosis requiring a change in adjuvant chemotherapy
. It is a diagnostic requirement for chondroblastic osteosarcoma
. It is associated with improved long-term survival indicating a good chemotherapeutic response
. It suggests the presence of an aggressive co-existing infection
. It mandates immediate amputation due to massive tissue death

Correct Answer & Explanation

. It is associated with improved long-term survival indicating a good chemotherapeutic response

Explanation

The degree of tumor necrosis following neoadjuvant chemotherapy is the single most important prognostic factor for overall survival in osteosarcoma. Greater than 90% necrosis is classified as a 'good response' and is correlated with significantly higher long-term survival rates.

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