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10. Pathology and Oncology MCQs

Practice Set 192 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 3821

Topic: Bone Tumors

Mutations in the isocitrate dehydrogenase 1 and 2 (IDH1/IDH2) genes are pathognomonic and most frequently associated with which of the following skeletal conditions?

. Multiple Hereditary Exostoses
. McCune-Albright syndrome
. Ollier disease and solitary enchondromas
. Osteogenesis imperfecta
. Neurofibromatosis type 1

Correct Answer & Explanation

. Ollier disease and solitary enchondromas

Explanation

IDH1 and IDH2 somatic mutations are heavily implicated in the pathogenesis of Ollier disease, Maffucci syndrome, and solitary enchondromas. They result in abnormal chondrocyte proliferation through oncometabolite accumulation.

Question 3822

Topic: 10. Pathology and Oncology

A 25-year-old male presents with a painful, eccentric, metaphyseal radiolucent lesion in the proximal tibia. Histology shows lobules of myxoid and chondroid tissue separated by fibrous septa containing multinucleated giant cells. What is the recommended treatment?

. Observation
. Intralesional curettage without adjuvant
. Intralesional curettage with local adjuvant (e.g., burring, phenol)
. Wide en bloc resection
. Chemotherapy

Correct Answer & Explanation

. Intralesional curettage with local adjuvant (e.g., burring, phenol)

Explanation

Chondromyxoid fibroma (CMF) is a benign but locally aggressive cartilage tumor. Treatment involves intralesional curettage; adding a local adjuvant (high-speed burr, phenol) decreases the relatively high recurrence rate.

Question 3823

Topic: Bone Tumors

A 55-year-old male is diagnosed with a grade 2 conventional chondrosarcoma of the proximal femur. There is no evidence of metastasis. What is the mainstay of treatment?

. Radiation therapy alone
. Neoadjuvant chemotherapy followed by wide resection
. Wide surgical resection alone
. Intralesional curettage with cementation
. High-dose systemic chemotherapy

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Conventional chondrosarcomas are largely resistant to both chemotherapy and radiation. The mainstay of treatment for intermediate to high-grade lesions is wide surgical resection with negative margins.

Question 3824

Topic: 10. Pathology and Oncology



A 32-year-old female presents with an incidental finding on a hand radiograph obtained after mild trauma. She has no pain at rest or night pain. Radiographs reveal a centrally located, lytic lesion in the proximal phalanx with stippled calcifications and no cortical breakthrough. What is the most appropriate next step in management?

. Curettage and bone grafting
. Core needle biopsy
. Observation with serial radiographs
. Marginal wide excision
. Neoadjuvant chemotherapy

Correct Answer & Explanation

. Observation with serial radiographs

Explanation

This is a classic asymptomatic enchondroma of the hand. Observation with serial radiographs is the standard of care for asymptomatic, non-destructive enchondromas without signs of malignant transformation.

Question 3825

Topic: 10. Pathology and Oncology

A 25-year-old male presents with a painless lump on his proximal humerus. Radiographs demonstrate a surface lesion causing saucerization of the underlying cortex with a well-defined sclerotic margin and no medullary involvement.

What is the most likely diagnosis?

. Periosteal osteosarcoma
. Osteochondroma
. Periosteal chondroma
. Parosteal osteosarcoma
. Chondroblastoma

Correct Answer & Explanation

. Periosteal chondroma

Explanation

Periosteal chondromas are benign, slow-growing cartilage tumors on the bone surface. Radiographically, they characteristically cause saucerization of the underlying cortex with a thick sclerotic margin.

Question 3826

Topic: 10. Pathology and Oncology

Which of the following imaging features is the most reliable indicator for differentiating a low-grade (Grade 1) chondrosarcoma from a benign enchondroma in a long bone?

. Presence of intralesional punctate calcifications
. Lesion size greater than 3 cm
. Location in the diaphysis rather than the metaphysis
. Endosteal scalloping involving greater than two-thirds of the cortical thickness
. Absence of periosteal reaction

Correct Answer & Explanation

. Endosteal scalloping involving greater than two-thirds of the cortical thickness

Explanation

Endosteal scalloping that involves more than 2/3 of the cortical thickness, along with cortical thickening and deep bone pain, highly suggests a low-grade chondrosarcoma over an enchondroma.

Question 3827

Topic: 10. Pathology and Oncology

A 22-year-old male presents with knee pain. Radiographs reveal an eccentric, heavily scalloped lytic lesion in the proximal tibial metaphysis with a sclerotic rim. Histology shows lobules of myxoid and chondroid tissue with stellate cells and hypercellular peripheries. What is the diagnosis?

. Giant cell tumor of bone
. Chondroblastoma
. Chondromyxoid fibroma
. Aneurysmal bone cyst
. Non-ossifying fibroma

Correct Answer & Explanation

. Chondromyxoid fibroma

Explanation

Chondromyxoid fibroma is a rare benign cartilage tumor presenting as an eccentric metaphyseal lesion. Its histology classically shows lobulated areas of stellate or spindle cells in a myxoid background with hypercellular margins.

Question 3828

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with chronic right knee pain. Radiographs show a well-circumscribed lytic lesion in the distal femoral epiphysis. Histological examination reveals mononuclear cells with longitudinal nuclear grooves and areas of "chicken-wire" calcification. What is the most likely diagnosis?

. Clear cell chondrosarcoma
. Chondroblastoma
. Giant cell tumor
. Eosinophilic granuloma
. Osteomyelitis

Correct Answer & Explanation

. Chondroblastoma

Explanation

Chondroblastoma is a benign cartilaginous tumor characteristically found in the epiphysis of skeletally immature patients. Histology typically reveals chondroblasts with grooved nuclei and pericellular "chicken-wire" calcification.

Question 3829

Topic: 10. Pathology and Oncology

In a skeletally mature patient with a solitary osteochondroma, malignant transformation to secondary chondrosarcoma is best indicated on MRI by a cartilage cap thickness greater than:

. 0.5 cm
. 1.0 cm
. 2.0 cm
. 4.0 cm
. 5.0 cm

Correct Answer & Explanation

. 2.0 cm

Explanation

A cartilage cap thickness greater than 2.0 cm in a skeletally mature adult is highly suspicious for malignant transformation to a secondary chondrosarcoma. Growth of the lesion after skeletal maturity is also a strong clinical indicator.

Question 3830

Topic: 10. Pathology and Oncology

Which of the following is the histological hallmark of a dedifferentiated chondrosarcoma?

. A gradual transition from benign enchondroma to low-grade chondrosarcoma
. An abrupt transition between a low-grade cartilage tumor and a high-grade, non-cartilaginous spindle cell sarcoma
. Bimorphic presence of well-differentiated cartilage islands surrounded by small blue round cells
. Mononuclear cells with grooved nuclei intermixed with osteoclast-like giant cells
. Clear cells with distinct cytoplasmic membranes and central cartilaginous matrix

Correct Answer & Explanation

. An abrupt transition between a low-grade cartilage tumor and a high-grade, non-cartilaginous spindle cell sarcoma

Explanation

Dedifferentiated chondrosarcoma is characterized by a bimorphic histological pattern featuring a well-differentiated (low-grade) cartilaginous component lying adjacent to a high-grade, non-cartilaginous sarcoma, with an abrupt transition between the two.

Question 3831

Topic: 10. Pathology and Oncology

A 35-year-old male is noted to have an asymptomatic, 1.5 cm well-circumscribed lesion in the proximal phalanx with stippled calcifications found incidentally on X-ray for a sprained finger.

What is the most appropriate management?

. Observation with serial radiographs
. Intralesional curettage and bone grafting
. Wide excision
. Core needle biopsy
. Prophylactic internal fixation

Correct Answer & Explanation

. Observation with serial radiographs

Explanation

Asymptomatic enchondromas discovered incidentally require only observation and serial radiographs to confirm stability. Surgical intervention is reserved for symptomatic lesions, enlarging lesions, or impending pathologic fractures.

Question 3832

Topic: Bone Tumors

Mutations in the EXT1 and EXT2 genes, seen in multiple hereditary exostoses (MHE), lead to the impaired synthesis of which of the following?

. Hyaluronic acid
. Heparan sulfate
. Chondroitin sulfate
. Keratan sulfate
. Type II collagen

Correct Answer & Explanation

. Heparan sulfate

Explanation

EXT1 and EXT2 gene mutations affect the EXT-polymerase complex, leading to impaired synthesis of heparan sulfate. This disruption alters normal Indian hedgehog (Ihh) signaling at the growth plate, leading to osteochondroma formation.

Question 3833

Topic: 10. Pathology and Oncology

What is the recommended surgical management for a biopsy-proven atypical cartilaginous tumor (Grade 1 chondrosarcoma) contained entirely within the medullary canal of the distal femur?

. Observation
. Extensive intralesional curettage with local adjuvant therapy (e.g., phenol, cryotherapy)
. Wide local excision with endoprosthetic reconstruction
. Above-knee amputation
. Radiation therapy

Correct Answer & Explanation

. Extensive intralesional curettage with local adjuvant therapy (e.g., phenol, cryotherapy)

Explanation

Atypical cartilaginous tumors (Grade 1 chondrosarcomas) in the long bones of the appendicular skeleton are safely and effectively treated with extensive intralesional curettage and local adjuvants. Wide resection is reserved for higher grade tumors or pelvic lesions.

Question 3834

Topic: 10. Pathology and Oncology
A 55-year-old male presents with deep pelvic pain. Radiographs show a large destructive mass in the ilium with "popcorn" calcifications. Core biopsy confirms Grade II chondrosarcoma. What is the most appropriate treatment?
. Neoadjuvant chemotherapy followed by wide resection
. Intralesional curettage with cementation
. Radiation therapy alone
. Wide surgical resection
. Radiofrequency ablation

Correct Answer & Explanation

. Wide surgical resection

Explanation

Intermediate to high-grade chondrosarcomas (Grades II and III), as well as any grade of chondrosarcoma in the pelvis, are treated with wide surgical resection. Chondrosarcomas are generally resistant to both standard chemotherapy and radiation.

Question 3835

Topic: 10. Pathology and Oncology

A 28-year-old female presents with multiple hard, bony swellings in her hands and several bluish soft-tissue nodules on her forearm that contain phleboliths on X-ray. What is her most likely diagnosis?

. Ollier disease
. Multiple hereditary exostoses
. Maffucci syndrome
. McCune-Albright syndrome
. Klippel-Trenaunay syndrome

Correct Answer & Explanation

. Maffucci syndrome

Explanation

Maffucci syndrome is characterized by the presence of multiple enchondromas associated with soft-tissue venous malformations (hemangiomas), which frequently contain calcified phleboliths. It carries a high risk of malignant transformation.

Question 3836

Topic: Bone Tumors

A 17-year-old boy presents with a firm mass on the surface of his proximal tibia. Imaging demonstrates a subperiosteal lesion causing saucerization of the outer cortex, bordered by solid reactive sclerosis.

There is no marrow invasion. What is the most likely diagnosis?

. Periosteal chondroma
. Parosteal osteosarcoma
. Osteoid osteoma
. Periosteal osteosarcoma
. Osteochondroma

Correct Answer & Explanation

. Periosteal chondroma

Explanation

Periosteal chondromas develop under the periosteum, characteristically eroding the underlying cortex (saucerization) while inducing a dense sclerotic margin. They lack the perpendicular "hair-on-end" periosteal reaction seen in periosteal osteosarcoma.

Question 3837

Topic: 10. Pathology and Oncology

Which of the following distinct histological patterns is characteristic of mesenchymal chondrosarcoma?

. Abrupt transition from well-differentiated cartilage to a high-grade spindle cell sarcoma
. Lobules of hypocellular hyaline cartilage permeating through pre-existing lamellar bone
. Epiphyseal clear cells interspersed with osteoclast-like giant cells
. Stellate cells in a myxoid background with hypercellular peripheries
. A highly cellular proliferation of small round blue cells with interspersed islands of well-differentiated hyaline cartilage

Correct Answer & Explanation

. A highly cellular proliferation of small round blue cells with interspersed islands of well-differentiated hyaline cartilage

Explanation

Mesenchymal chondrosarcoma is defined by a bimorphic histology featuring undifferentiated small blue round cells surrounding discrete islands of relatively well-differentiated benign-appearing hyaline cartilage.

Question 3838

Topic: Bone Tumors

The IDH1 and IDH2 mutations commonly found in central chondrosarcomas and enchondromatosis syndromes promote tumorigenesis by producing which of the following oncometabolites?

. Fumarate
. Succinate
. D-2-hydroxyglutarate (D-2-HG)
. Alpha-ketoglutarate
. Citrate

Correct Answer & Explanation

. D-2-hydroxyglutarate (D-2-HG)

Explanation

Mutant IDH1/2 enzymes gain a neomorphic activity that converts alpha-ketoglutarate into the oncometabolite D-2-hydroxyglutarate (D-2-HG). This leads to DNA hypermethylation and altered cellular differentiation.

Question 3839

Topic: 10. Pathology and Oncology

A 45-year-old male presents with hip pain. Radiographs reveal a lytic lesion in the proximal femoral epiphysis. Biopsy reveals cells with distinct borders, clear cytoplasm, and central round nuclei in a background of cartilaginous matrix with scattered giant cells. Diagnosis?

. Chondroblastoma
. Clear cell chondrosarcoma
. Chondromyxoid fibroma
. Metastatic renal cell carcinoma
. Giant cell tumor of bone

Correct Answer & Explanation

. Clear cell chondrosarcoma

Explanation

Clear cell chondrosarcoma typically occurs in the epiphyses of adults (resembling chondroblastoma radiographically, but in an older age group). Histologically, it displays large cells with clear cytoplasm and distinct boundaries alongside a cartilaginous matrix.

Question 3840

Topic: 10. Pathology and Oncology

Patients with Multiple Hereditary Exostoses (MHE) have an increased lifetime risk of malignant transformation compared to the general population. What is the approximate rate of malignant transformation in MHE?

. Less than 1%
. 1% to 5%
. 10% to 15%
. 25% to 30%
. Greater than 50%

Correct Answer & Explanation

. 1% to 5%

Explanation

While solitary osteochondromas have a malignant transformation risk of <1%, patients with Multiple Hereditary Exostoses (MHE) have a higher lifetime risk, typically estimated between 1% and 5%.

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