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10. Pathology and Oncology MCQs

Practice Set 297 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 5921

Topic: 10. Pathology and Oncology

A 15-year-old male presents with chronic knee pain. Radiographs display a well-circumscribed, eccentrically located lytic lesion with a thin sclerotic margin in the proximal tibial epiphysis. Biopsy shows polygonal mononuclear cells with longitudinally clefted nuclei and areas of "chicken-wire" intercellular calcification. Following extended curettage and bone grafting, what is the most common complication of this lesion?

. Malignant transformation
. Local recurrence
. Metastasis to the lungs
. Pathologic fracture
. Joint stiffness

Correct Answer & Explanation

. Local recurrence

Explanation

The diagnosis is chondroblastoma, a benign but locally aggressive epiphyseal tumor characterized by clefted nuclei and "chicken-wire" calcification. The most common complication following intralesional curettage is local recurrence, occurring in approximately 10-20% of cases.

Question 5922

Topic: Bone Tumors
A 9-year-old girl is evaluated for a limp and a leg-length discrepancy. Physical exam notes large café-au-lait macules with irregular, "coast of Maine" borders. She also has a history of early-onset menses. Radiographs show a polyostotic intramedullary lesion with a hazy, "ground-glass" appearance. This clinical syndrome is associated with a mutation affecting which of the following?
. Tyrosine kinase receptor
. Gs alpha subunit of adenylyl cyclase
. TGF-beta receptor
. Fibroblast growth factor receptor 3
. Parathyroid hormone receptor

Correct Answer & Explanation

. Gs alpha subunit of adenylyl cyclase

Explanation

McCune-Albright syndrome consists of polyostotic fibrous dysplasia, precocious puberty, and café-au-lait spots. It is caused by a somatic activating mutation in the GNAS gene, which encodes the Gs alpha subunit of adenylyl cyclase, leading to continuous cAMP production.

Question 5923

Topic: 10. Pathology and Oncology

A 30-year-old female presents with a slow-growing, mildly painful mass in her anterior shin. Plain radiographs reveal an eccentric, multi-loculated, "soap-bubble" osteolytic lesion in the anterior tibial diaphysis. Histology shows nests of epithelial cells within a fibrous stroma. Which of the following conditions is most frequently considered a precursor or is commonly found coexisting with this specific tumor?

. Non-ossifying fibroma
. Osteofibrous dysplasia
. Fibrous dysplasia
. Paget disease of bone
. Chondromyxoid fibroma

Correct Answer & Explanation

. Osteofibrous dysplasia

Explanation

The patient has an adamantinoma, a rare, low-grade malignant bone tumor that almost exclusively occurs in the anterior tibial diaphysis. It is frequently associated with, or thought to evolve from, osteofibrous dysplasia (Campanacci disease), which shares overlapping clinical and histologic features.

Question 5924

Topic: 10. Pathology and Oncology

A 25-year-old male with a known history of Ollier disease presents with new, rapidly worsening pain and a palpable mass in his proximal humerus. Radiographs show a previously stable enchondroma that now exhibits cortical destruction and a soft tissue mass containing rings-and-arcs calcifications.

What is the most likely diagnosis of this new aggressive lesion?

. Secondary conventional chondrosarcoma
. Ewing sarcoma
. Osteoblastoma
. Aneurysmal bone cyst
. Telangiectatic osteosarcoma

Correct Answer & Explanation

. Secondary conventional chondrosarcoma

Explanation

Patients with Ollier disease (multiple enchondromatosis) have a high risk (up to 30-50%) of malignant transformation. The most common malignancy to arise from a pre-existing enchondroma is a secondary conventional chondrosarcoma, indicated here by cortical destruction and cartilaginous matrix outside the bone.

Question 5925

Topic: 10. Pathology and Oncology

A 72-year-old male presents with new onset back pain, generalized fatigue, and recent unexplained fractures. Laboratory tests show hypercalcemia, anemia, and elevated total protein with a monoclonal M-spike. Which condition should be high on the differential diagnosis?

. Osteoporosis
. Ankylosing Spondylitis
. Metastatic prostate cancer
. Multiple Myeloma
. Renal Osteodystrophy

Correct Answer & Explanation

. Multiple Myeloma

Explanation

The constellation of new-onset back pain, generalized fatigue, unexplained fractures, hypercalcemia, anemia, and a monoclonal M-spike (on serum protein electrophoresis) is highly suggestive of Multiple Myeloma. This plasma cell dyscrasia leads to lytic bone lesions, pain, and can cause pathological fractures. While osteoporosis causes fractures, it doesn't typically present with hypercalcemia, anemia, or an M-spike. Ankylosing spondylitis has inflammatory back pain features. Metastatic prostate cancer typically causes osteoblastic lesions (though can be lytic) and may cause anemia and hypercalcemia, but the M-spike is more specific to myeloma. Renal osteodystrophy is related to kidney disease.

Question 5926

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with knee pain. Radiographs show a sunburst periosteal reaction in the distal femur, and biopsy confirms conventional osteosarcoma. Which of the following histologic findings following neoadjuvant chemotherapy is the most important prognostic factor?

. Initial mitotic rate
. Presence of skip metastases
. Tumor necrosis greater than 90%
. Presence of vascular invasion
. Degree of chondroblastic matrix

Correct Answer & Explanation

. Tumor necrosis greater than 90%

Explanation

The degree of tumor necrosis following neoadjuvant chemotherapy is one of the most reliable prognostic indicators in osteosarcoma. Necrosis greater than 90% is associated with significantly improved long-term survival.

Question 5927

Topic: 10. Pathology and Oncology



A 55-year-old male presents with a large, slow-growing, painless mass deep in his thigh. MRI shows a predominantly fatty mass with thick septations. Which genetic abnormality confirms the diagnosis of an atypical lipomatous tumor (ALT)?

. t(11;22) translocation
. SYT-SSX fusion
. Amplification of MDM2 and CDK4
. t(12;16) translocation
. Mutation of the EXT1 gene

Correct Answer & Explanation

. Amplification of MDM2 and CDK4

Explanation

Atypical lipomatous tumors (ALT) and well-differentiated liposarcomas are characterized by the amplification of MDM2 and CDK4 genes on chromosome 12q13-15. This genetic finding firmly distinguishes ALT from benign lipomas.

Question 5928

Topic: 10. Pathology and Oncology



A 28-year-old male with a known history of Hereditary Multiple Exostoses (HME) presents with new, progressive pain in his pelvis. Which of the following MRI findings is most concerning for malignant transformation?

. Cartilage cap thickness of 0.5 cm
. Cartilage cap thickness of 2.5 cm
. Medullary continuity with the host bone
. Presence of a bursa over the exostosis
. Migration of the exostosis away from the joint line

Correct Answer & Explanation

. Cartilage cap thickness of 2.5 cm

Explanation

In adults with HME, a cartilage cap thickness greater than 1.5 to 2.0 cm on MRI is highly suspicious for secondary chondrosarcoma. Pain and lesion growth after skeletal maturity are the hallmark clinical signs of malignant transformation.

Question 5929

Topic: 10. Pathology and Oncology

Which of the following osteosarcoma subtypes is typically characterized as low-grade, occurs primarily on the posterior aspect of the distal femur, and is often associated with MDM2 and CDK4 amplification?

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

Correct Answer & Explanation

. Parosteal osteosarcoma

Explanation

Parosteal osteosarcoma is a low-grade surface osteosarcoma that typically arises on the posterior distal femur. Like atypical lipomatous tumors, it is frequently driven by MDM2 and CDK4 amplification and requires wide surgical excision without neoadjuvant chemotherapy.

Question 5930

Topic: Bone Tumors

A 16-year-old boy undergoes resection of a distal femur conventional osteosarcoma.

What is the standard neoadjuvant chemotherapy regimen utilized for this malignancy?

. Vincristine, doxorubicin, and cyclophosphamide
. Methotrexate, doxorubicin, and cisplatin
. Ifosfamide and etoposide
. Imatinib mesylate
. Isolated limb perfusion with TNF-alpha

Correct Answer & Explanation

. Methotrexate, doxorubicin, and cisplatin

Explanation

The standard first-line chemotherapy regimen for conventional osteosarcoma is MAP, which stands for high-dose Methotrexate, Adriamycin (doxorubicin), and Platinol (cisplatin). This regimen is typically administered both before (neoadjuvant) and after (adjuvant) surgical resection.

Question 5931

Topic: 10. Pathology and Oncology

A 45-year-old female presents with a soft tissue mass in her subcutaneous forearm. MRI reveals a homogeneous mass that is hyperintense on T1-weighted images and demonstrates complete suppression on STIR sequences. What is the most likely diagnosis?

. Myxoid liposarcoma
. Pleomorphic liposarcoma
. Intramuscular hemangioma
. Benign lipoma
. Atypical lipomatous tumor

Correct Answer & Explanation

. Benign lipoma

Explanation

A mass that is uniformly bright on T1 and completely suppresses on fat-saturated sequences (like STIR) is composed purely of mature adipose tissue. This is characteristic of a benign lipoma, which typically lacks the thick septations or nodularity seen in liposarcomas.

Question 5932

Topic: 10. Pathology and Oncology

Hereditary Multiple Exostoses (HME) is an autosomal dominant disorder caused by mutations in the EXT1 or EXT2 genes. What is the primary function of the proteins encoded by these genes?

. Regulating p53 tumor suppression
. Synthesis of heparan sulfate
. Chondrocyte apoptosis pathway regulation
. Type II collagen synthesis
. Regulating MDM2 degradation

Correct Answer & Explanation

. Synthesis of heparan sulfate

Explanation

The EXT1 and EXT2 genes encode glycosyltransferases responsible for the synthesis of heparan sulfate. A deficiency in heparan sulfate disrupts normal Indian hedgehog (Ihh) signaling, leading to abnormal chondrocyte proliferation and the formation of multiple osteochondromas.

Question 5933

Topic: 10. Pathology and Oncology



An 18-year-old presents with acute thigh pain. Radiographs show a purely lytic, expansile lesion in the distal femur. MRI demonstrates multiple fluid-fluid levels. Biopsy reveals high-grade malignant cells producing osteoid. What is the most likely diagnosis?

. Aneurysmal bone cyst
. Telangiectatic osteosarcoma
. Chondroblastoma
. Giant cell tumor of bone
. Ewing sarcoma

Correct Answer & Explanation

. Telangiectatic osteosarcoma

Explanation

Telangiectatic osteosarcoma is an aggressive variant characterized by large blood-filled cystic spaces with fluid-fluid levels on MRI, closely mimicking an aneurysmal bone cyst (ABC). The presence of high-grade malignant cells producing osteoid differentiates it from a benign ABC.

Question 5934

Topic: 10. Pathology and Oncology

A 60-year-old man has a biopsy-proven atypical lipomatous tumor (ALT) in his posterior thigh.

There is no clinical or histologic evidence of dedifferentiation. Which of the following is the most appropriate surgical management?

. Radical compartment resection
. Marginal excision with careful follow-up
. Preoperative radiation followed by wide excision
. Intralesional curettage
. Above-knee amputation

Correct Answer & Explanation

. Marginal excision with careful follow-up

Explanation

Marginal excision is generally acceptable for ALT in the extremities because they do not metastasize unless they undergo dedifferentiation. While wide margins are ideal if functionally acceptable, function-sparing marginal resection is the standard of care with close monitoring for local recurrence.

Question 5935

Topic: 10. Pathology and Oncology

A 14-year-old girl is diagnosed with a conventional osteosarcoma of the proximal tibia. As part of her local staging, an MRI of the entire tibia is ordered. What is the primary purpose of imaging the entire involved bone?

. To assess the size of the extraosseous soft tissue mass
. To detect the presence of skip metastases
. To measure the thickness of the periosteal reaction
. To evaluate for deep venous thrombosis
. To determine the degree of joint effusion

Correct Answer & Explanation

. To detect the presence of skip metastases

Explanation

A skip metastasis is a separate focus of tumor within the same bone or a transarticular adjacent bone, occurring in a small percentage of osteosarcomas. A whole-bone MRI is essential to detect these lesions because their presence significantly worsens the prognosis and alters surgical planning.

Question 5936

Topic: 10. Pathology and Oncology

When evaluating a soft-tissue mass suspected to be lipomatous, which of the following features on MRI is most indicative of an atypical lipomatous tumor (ALT) or liposarcoma rather than a simple lipoma?

. Size less than 3 cm
. Superficial subcutaneous location
. Thick, nodular septations greater than 2 mm
. Complete loss of signal on fat-saturated images
. Homogeneous hyperintensity on T1 sequences

Correct Answer & Explanation

. Thick, nodular septations greater than 2 mm

Explanation

Features suggesting a liposarcoma or ALT over a benign lipoma include deep subfascial location, size greater than 5 cm, and the presence of thick (>2 mm) or nodular septations. Benign lipomas are typically superficial, homogeneous, and suppress completely on fat-saturated MRI.

Question 5937

Topic: 10. Pathology and Oncology
A 15-year-old male presents with distal femur pain. Imaging reveals a mixed lytic/sclerotic lesion with a 'sunburst' periosteal reaction. Biopsy confirms conventional high-grade osteosarcoma. After initiating multi-agent neoadjuvant chemotherapy, what is the most important histologic prognostic factor evaluated at the time of wide surgical resection?
. Percentage of chondroblastic differentiation
. Tumor necrosis greater than 90%
. Presence of skip metastases
. Decreased mitotic rate to less than 5 per HPF
. Lymphocytic infiltration grading

Correct Answer & Explanation

. Tumor necrosis greater than 90%

Explanation

The most important prognostic factor for conventional osteosarcoma (after the presence of metastases) is the percentage of tumor necrosis following neoadjuvant chemotherapy. Necrosis greater than 90% (Huvos Grade III/IV) is associated with significantly improved overall survival.

Question 5938

Topic: 10. Pathology and Oncology

A 58-year-old man presents with a large, slow-growing mass deep in his right thigh. MRI demonstrates a predominantly lipomatous mass with thick, nodular septations.

Core needle biopsy confirms an Atypical Lipomatous Tumor (ALT). Which of the following genetic alterations is diagnostic for this lesion?

. t(11;22) translocation
. t(12;16) translocation
. MDM2 and CDK4 gene amplification
. GNAS mutation
. Loss of heterozygosity of RB1

Correct Answer & Explanation

. MDM2 and CDK4 gene amplification

Explanation

Atypical lipomatous tumors (ALT) and well-differentiated liposarcomas (WDLPS) are characterized by ring chromosomes or giant marker chromosomes leading to the amplification of MDM2 and CDK4 genes on chromosome 12q13-15.

Question 5939

Topic: 10. Pathology and Oncology

A 22-year-old female presents with a painless mass on the posterior aspect of her distal femur. Radiographs show a dense, lobulated, heavily ossified mass on the surface of the bone with a radiolucent cleft between the tumor and the underlying cortex.

What is the most likely diagnosis?

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

Correct Answer & Explanation

. Parosteal osteosarcoma

Explanation

Parosteal osteosarcoma classically presents as a densely ossified, lobulated mass on the posterior distal femur in young adults. The radiolucent cleft separating the tumor from the cortex is known as the 'string sign'.

Question 5940

Topic: 10. Pathology and Oncology

A 32-year-old male with a known history of Hereditary Multiple Exostoses (HME) presents with new, increasing pain and enlargement of an osteochondroma on his left ilium.

Which of the following MRI findings is most indicative of malignant transformation to a secondary chondrosarcoma?

. Cartilage cap thickness of 1.2 cm
. Cartilage cap thickness greater than 2.0 cm
. Presence of marrow continuity with the host bone
. Peripheral ring-and-arc calcifications
. Absence of surrounding soft tissue edema

Correct Answer & Explanation

. Cartilage cap thickness greater than 2.0 cm

Explanation

In skeletally mature patients with HME, a cartilage cap thickness greater than 1.5 to 2.0 cm on MRI is highly suspicious for malignant transformation to secondary chondrosarcoma. The pelvis is the most common site for this transformation.

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