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10. Pathology and Oncology MCQs

Practice Set 124 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 2461

Topic: 10. Pathology and Oncology
A 16-year-old male undergoes neoadjuvant chemotherapy followed by wide resection of a distal femur osteosarcoma. Pathology reveals 95% tumor necrosis. According to the Huvos grading system, what grade is this, and what is its clinical significance?
. Grade I; indicates a poor response and necessitates amputation
. Grade II; indicates an intermediate response requiring radiation
. Grade III; indicates a good response and correlates with better survival
. Grade IV; indicates an excellent response with no viable cells remaining
. Grade V; indicates a complete cure

Correct Answer & Explanation

. Grade III; indicates a good response and correlates with better survival

Explanation

The Huvos grading system measures histologic response to chemotherapy in osteosarcoma. Grade I: <50% necrosis. Grade II: 50-90% necrosis. Grade III: >90% necrosis but with viable tumor cells. Grade IV: 100% necrosis (no viable cells). A finding of 95% necrosis falls into Grade III, which is considered a 'good response' and is highly prognostic of improved overall survival.

Question 2462

Topic: 10. Pathology and Oncology

According to Mirels' criteria for evaluating the risk of a pathologic fracture in a long bone affected by a metastatic lesion, which of the following clinical scenarios yields the highest possible score and mandates prophylactic fixation?

. Blastic lesion, upper extremity, < 1/3 of cortex, mild pain
. Blastic lesion, lower extremity, < 1/3 of cortex, functional pain
. Mixed lesion, upper extremity, 1/3-2/3 of cortex, moderate pain
. Lytic lesion, upper extremity, > 2/3 of cortex, mild pain
. Lytic lesion, lower extremity, > 2/3 of cortex, functional pain

Correct Answer & Explanation

. Lytic lesion, lower extremity, > 2/3 of cortex, functional pain

Explanation

Mirels' criteria score four variables from 1 to 3: Site (Upper=1, Lower=2, Peritrochanteric=3), Pain (Mild=1, Moderate=2, Functional=3), Lesion Nature (Blastic=1, Mixed=2, Lytic=3), and Size (<1/3=1, 1/3-2/3=2, >2/3=3). A lytic lesion (3) in the lower extremity (wait, peritrochanteric is 3, but lower extremity generally is scored high; standard Mirels scores Lower limb as 2 and peritrochanteric as 3. Given the options, Lytic (3) + Lower extremity (at least 2) + >2/3 cortex (3) + functional pain (3) yields a score of 11 or 12, which is the highest among the choices and strictly indicates prophylactic fixation.

Question 2463

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphyseal femur lesion accompanied by an 'onion-skin' periosteal reaction. Biopsy reveals uniform small round blue cells. Molecular analysis demonstrates a t(11;22)(q24;q12) translocation. Which of the following fusion genes is pathognomonic for this tumor?

. SYT-SSX
. EWS-FLI1
. TLS-CHOP
. PAX3-FKHR
. COL1A1-PDGFB

Correct Answer & Explanation

. EWS-FLI1

Explanation

The clinical scenario and t(11;22) translocation are classic for Ewing sarcoma, which is characterized by the EWS-FLI1 fusion gene in approximately 85% of cases. SYT-SSX is associated with Synovial Sarcoma; TLS-CHOP with Myxoid Liposarcoma; PAX3-FKHR with Alveolar Rhabdomyosarcoma; and COL1A1-PDGFB with Dermatofibrosarcoma protuberans.

Question 2464

Topic: Bone Tumors

Which of the following clinical or radiographic features most reliably differentiates an osteoblastoma from an osteoid osteoma?

. Presence of a radiolucent nidus surrounded by sclerosis
. Pain that is characteristically and completely relieved by NSAIDs
. Nidus size greater than 2 cm
. Location in the posterior elements of the spine
. Histological presence of woven bone lined by prominent osteoblasts

Correct Answer & Explanation

. Nidus size greater than 2 cm

Explanation

Osteoblastoma and osteoid osteoma are histologically identical, both featuring woven bone lined by prominent osteoblasts. The primary differentiating feature is size; osteoblastomas have a nidus greater than 2 cm (some sources use >1.5 cm), whereas osteoid osteomas are smaller. Additionally, the pain of osteoblastoma is often not predictably relieved by NSAIDs/aspirin, unlike osteoid osteoma.

Question 2465

Topic: 10. Pathology and Oncology

A 60-year-old male undergoes wide resection of a massive pelvic tumor. Pathology confirms a diagnosis of dedifferentiated chondrosarcoma. Which of the following is the hallmark histological finding for this tumor?

. Uniform, well-differentiated hyaline cartilage lobules
. Biphasic appearance with low-grade cartilage abruptly transitioning to high-grade non-cartilaginous sarcoma
. Extensive 'chicken-wire' calcifications with mononuclear cells
. Nests of chondroblasts surrounded by giant cells
. Small round blue cells forming pseudorosettes

Correct Answer & Explanation

. Biphasic appearance with low-grade cartilage abruptly transitioning to high-grade non-cartilaginous sarcoma

Explanation

Dedifferentiated chondrosarcoma is characterized by a distinctive 'biphasic' histological pattern. It consists of a low-grade hyaline cartilage tumor that abruptly juxtaposes against a high-grade, non-cartilaginous spindle cell sarcoma (such as osteosarcoma, fibrosarcoma, or undifferentiated pleomorphic sarcoma) without a transitional zone. This entity carries a very poor prognosis.

Question 2466

Topic: 10. Pathology and Oncology

A 24-year-old female presents with a slow-growing, painless mass on the posterior aspect of her distal femur. Radiographs show a densely ossified mass attached to the posterior cortex by a broad base. Biopsy suggests a low-grade parosteal osteosarcoma. Which of the following molecular alterations is pathognomonic and critical in distinguishing this lesion from benign mimics like myositis ossificans?

. EXT1 mutation
. TP53 deletion
. MDM2 gene amplification
. t(11;22) translocation
. t(X;18) translocation

Correct Answer & Explanation

. MDM2 gene amplification

Explanation

Parosteal osteosarcoma is a low-grade, surface-based osteosarcoma that typically arises on the posterior aspect of the distal femur. It is characterized at the molecular level by the amplification of the MDM2 and CDK4 genes (located on chromosome 12q13-15). Identification of MDM2 amplification via FISH or immunohistochemistry is highly sensitive and specific, helping distinguish parosteal osteosarcoma from benign reactive conditions like myositis ossificans or osteochondromas.

Question 2467

Topic: 10. Pathology and Oncology

A 25-year-old male presents with a slow-growing soft tissue mass in his foot. Biopsy confirms synovial sarcoma. Which of the following cytogenetic abnormalities is most characteristically associated with this tumor?

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

Correct Answer & Explanation

. t(X;18)

Explanation

Synovial sarcoma is characterized by the t(X;18)(p11;q11) translocation, resulting in the SYT-SSX fusion gene. This is tested frequently on board exams. t(11;22) is associated with Ewing sarcoma, t(12;16) with myxoid liposarcoma, and t(2;13) with alveolar rhabdomyosarcoma.

Question 2468

Topic: Bone Tumors

A 25-year-old female presents with a slowly enlarging mass on the posterior aspect of her distal femur. Plain radiographs show a heavily ossified, juxtacortical mass with a broad base on the surface of the bone, and a radiolucent cleft separating portions of the tumor from the underlying cortex. Medullary involvement is minimal. What is the most likely diagnosis?

. Osteochondroma
. Periosteal osteosarcoma
. Parosteal osteosarcoma
. High-grade surface osteosarcoma
. Myositis ossificans

Correct Answer & Explanation

. Parosteal osteosarcoma

Explanation

Parosteal osteosarcoma is a low-grade surface osteosarcoma typically found on the posterior distal femur. Radiographically, it appears as a heavily ossified mass with a broad base and a characteristic 'string sign' (a radiolucent cleft separating the tumor from the underlying cortex). It is distinct from periosteal osteosarcoma, which has a sunburst or hair-on-end appearance and is more chondroblastic.

Question 2469

Topic: Bone Tumors

A 16-year-old boy presents with progressive, nocturnal thigh pain that is rapidly and completely relieved by ibuprofen. Radiographs demonstrate a 7 mm radiolucent nidus in the femoral diaphysis surrounded by dense reactive cortical sclerosis. Which inflammatory mediator is found in extraordinarily high concentrations within this nidus, explaining the efficacy of NSAIDs?

. Interleukin-1 (IL-1)
. Interleukin-6 (IL-6)
. Tumor necrosis factor-alpha (TNF-alpha)
. Prostaglandin E2 (PGE2)
. Leukotriene B4

Correct Answer & Explanation

. Prostaglandin E2 (PGE2)

Explanation

The clinical and radiographic presentation is classic for an osteoid osteoma. The nidus of an osteoid osteoma produces enormous quantities of prostaglandins, particularly Prostaglandin E2 (PGE2), at levels 100 to 1,000 times higher than surrounding normal tissue. This massive local PGE2 production lowers the threshold of unmyelinated nerve fibers, causing the severe nocturnal pain. NSAIDs provide dramatic relief by inhibiting cyclooxygenase (COX), thereby blocking prostaglandin synthesis.

Question 2470

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with progressive knee pain and swelling. Radiographs reveal an aggressive, ill-defined diaphyseal lesion of the distal femur with a lamellated 'onion-skin' periosteal reaction. A biopsy confirms a small round blue cell tumor. Which of the following cytogenetic abnormalities is most characteristic of this malignancy?

. t(11;22)(q24;q12) resulting in the EWS-FLI1 fusion protein
. t(9;22)(q34;q11) resulting in the BCR-ABL fusion protein
. t(X;18)(p11;q11) resulting in the SYT-SSX fusion protein
. t(12;16)(q13;p11) resulting in the FUS-CHOP fusion protein
. t(2;13)(q35;q14) resulting in the PAX3-FOXO1 fusion protein

Correct Answer & Explanation

. t(11;22)(q24;q12) resulting in the EWS-FLI1 fusion protein

Explanation

The clinical, radiographic, and histological findings are highly characteristic of Ewing sarcoma. Ewing sarcoma is a small round blue cell tumor most commonly found in the diaphysis of long bones in children and adolescents. The classic cytogenetic hallmark is the t(11;22)(q24;q12) chromosomal translocation, which fuses the EWS gene on chromosome 22 with the FLI1 gene on chromosome 11, found in approximately 85% of cases.

Question 2471

Topic: 10. Pathology and Oncology

A 40-year-old patient undergoes biopsy of a heavily calcified diaphyseal lesion in the proximal femur. Pathology demonstrates malignant chondroid cells permeating the medullary bone. Molecular testing reveals a mutation in the isocitrate dehydrogenase 1 (IDH1) gene. This mutation is the hallmark of which of the following conditions?

. Ollier disease
. Multiple Hereditary Exostoses
. McCune-Albright syndrome
. Neurofibromatosis type 1
. Li-Fraumeni syndrome

Correct Answer & Explanation

. Ollier disease

Explanation

IDH1 and IDH2 gene mutations are found in the vast majority of central chondrosarcomas and enchondromas. They are the underlying genetic abnormality in Ollier disease and Maffucci syndrome (multiple enchondromatosis). In contrast, Multiple Hereditary Exostoses (osteochondromas) is associated with EXT1 and EXT2 mutations.

Question 2472

Topic: 10. Pathology and Oncology

A 14-year-old female undergoes 10 weeks of neoadjuvant chemotherapy followed by surgical resection of a conventional high-grade osteosarcoma in her distal femur. The pathologist examines the resected specimen. Which of the following histologic parameters is the most powerful predictor of long-term overall survival in this patient?

. Absence of skip metastases in the proximal medullary canal
. Mitotic rate of the residual viable tumor cells
. Percentage of tumor necrosis in response to chemotherapy
. Presence of clear cell variant morphology
. Extent of chondroid matrix formation

Correct Answer & Explanation

. Percentage of tumor necrosis in response to chemotherapy

Explanation

The degree of tumor necrosis after neoadjuvant chemotherapy is the single most important and reliable prognostic factor in conventional osteosarcoma. According to the Huvos grading system, a 'good histologic response' is defined as >90% tumor necrosis, which strongly correlates with improved long-term disease-free and overall survival.

Question 2473

Topic: 10. Pathology and Oncology

A 30-year-old male presents with a slow-growing, painful soft tissue mass near his knee. Biopsy confirms the diagnosis of synovial sarcoma. Which of the following cytogenetic translocations and resultant fusion genes is pathognomonic for this tumor?

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

Correct Answer & Explanation

. t(X;18) resulting in SYT-SSX

Explanation

Synovial sarcoma is characterized by the pathognomonic balanced translocation t(X;18)(p11;q11), which results in the fusion of the SYT gene on chromosome 18 with one of the SSX genes on the X chromosome. t(11;22) is found in Ewing sarcoma, t(12;16) in myxoid liposarcoma, and t(2;13) in alveolar rhabdomyosarcoma.

Question 2474

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a permeative lytic lesion in the diaphysis of his femur with an associated 'onion-skin' periosteal reaction. Biopsy reveals sheets of uniform small blue round cells. Which of the following chromosomal translocations is most characteristic of this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical, radiographic, and histologic presentation is classic for Ewing sarcoma. The t(11;22)(q24;q12) translocation is present in 85-90% of Ewing sarcomas, resulting in the EWS-FLI1 fusion gene. t(X;18) is associated with synovial sarcoma; t(2;13) with alveolar rhabdomyosarcoma; t(12;16) with myxoid liposarcoma; and t(9;22) is found in chronic myelogenous leukemia and mesenchymal chondrosarcoma.

Question 2475

Topic: Bone Tumors

A 19-year-old male presents with persistent dull back pain that is not relieved by ibuprofen. Radiographs and a CT scan reveal a 3.5 cm expansile, radiolucent lesion in the posterior elements of L3 with a thin sclerotic rim. Histologically, the lesion consists of interlacing trabeculae of woven bone lined by prominent osteoblasts. What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Giant cell tumor
. Chondroblastoma

Correct Answer & Explanation

. Osteoblastoma

Explanation

Both osteoid osteoma and osteoblastoma share identical histologic features (woven bone trabeculae lined by a single layer of osteoblasts with loose fibrovascular stroma). However, osteoblastomas are distinguished by being larger (>2 cm), being locally aggressive (expansile), and causing pain that is typically less responsive to NSAIDs compared to the classic nocturnal, NSAID-responsive pain of osteoid osteoma. The posterior elements of the spine are a classic location.

Question 2476

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphyseal femur lesion showing an 'onion skin' periosteal reaction. Biopsy shows small round blue cells. Which chromosomal translocation is most classically associated with this diagnosis?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. Ewing sarcoma is classically associated with the t(11;22) translocation, creating the EWS-FLI1 fusion protein (found in about 85% of cases). t(X;18) is associated with synovial sarcoma. t(12;16) is associated with myxoid liposarcoma. t(2;13) is associated with alveolar rhabdomyosarcoma. t(9;22) is the Philadelphia chromosome seen in CML and ALL.

Question 2477

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with pain and swelling in his mid-thigh. Radiographs show a diaphyseal permeative lesion with an 'onion skin' periosteal reaction. Biopsy reveals small round blue cells. Which chromosomal translocation is most characteristically associated with this tumor?

. t(11;22)(q24;q12)
. t(X;18)(p11;q11)
. t(12;16)(q13;p11)
. t(9;22)(q22;q12)
. t(2;13)(q35;q14)

Correct Answer & Explanation

. t(11;22)(q24;q12)

Explanation

The clinical and radiographic presentation describes Ewing's sarcoma. The pathognomonic translocation is t(11;22)(q24;q12), which fuses the EWS gene on chromosome 22 with the FLI1 gene on chromosome 11. t(X;18) is associated with synovial sarcoma; t(12;16) with myxoid liposarcoma; and t(2;13) with alveolar rhabdomyosarcoma.

Question 2478

Topic: 10. Pathology and Oncology

A 28-year-old woman undergoes a biopsy of a slow-growing, deep soft-tissue mass in her thigh. Cytogenetics reveal a t(X;18)(p11;q11) chromosomal translocation. Which of the following is the most likely diagnosis?

. Ewing sarcoma
. Clear cell sarcoma
. Synovial sarcoma
. Myxoid liposarcoma
. Alveolar rhabdomyosarcoma

Correct Answer & Explanation

. Synovial sarcoma

Explanation

Synovial sarcoma is classically associated with the t(X;18)(p11;q11) translocation, which results in the SYT-SSX fusion gene. This molecular marker is highly specific and sensitive for synovial sarcoma, a high-grade soft tissue sarcoma commonly found near (but rarely within) large joints of young adults.

Question 2479

Topic: 10. Pathology and Oncology

A 62-year-old male presents with severe thigh pain. Imaging reveals a large, destructive lytic lesion in the proximal femur with an impending fracture (Mirels score of 10). Biopsy confirms multiple myeloma. He undergoes prophylactic intramedullary nailing. What is the most critical next step in the local management of this extremity?

. Observation with serial radiographs
. Post-operative radiation therapy
. Intravenous bisphosphonates alone
. Systemic chemotherapy alone
. Denosumab injections

Correct Answer & Explanation

. Post-operative radiation therapy

Explanation

Plasmacytoma and multiple myeloma lesions are highly radiosensitive. Following prophylactic stabilization of an impending or actual pathologic fracture from myeloma, post-operative radiation therapy is indicated to control local disease progression, alleviate pain, and prevent eventual hardware failure.

Question 2480

Topic: 10. Pathology and Oncology

Which of the following surface variants of osteosarcoma is typically the lowest histological grade, primarily affects the posterior aspect of the distal femur, and carries the best overall prognosis following wide resection?

. Conventional intramedullary osteosarcoma
. Periosteal osteosarcoma
. Parosteal osteosarcoma
. High-grade surface osteosarcoma
. Telangiectatic osteosarcoma

Correct Answer & Explanation

. Parosteal osteosarcoma

Explanation

Parosteal osteosarcoma is a low-grade, surface-based malignant bone-forming tumor that arises from the outer layer of the periosteum. It heavily favors the posterior metaphysis of the distal femur. Because it is usually low-grade, it carries an excellent prognosis (over 90% survival) when treated with wide surgical resection alone, often not requiring chemotherapy unless there is a dedifferentiated component.

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