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10. Pathology and Oncology MCQs

Practice Set 194 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 3861

Topic: 10. Pathology and Oncology

A 35-year-old male presents with chronic hip pain. Radiographs demonstrate a lytic lesion with a sclerotic margin localized specifically to the proximal femoral epiphysis. Histological analysis shows cells with abundant clear cytoplasm and distinct cell membranes, mixed with areas of conventional chondrosarcoma. What is the most likely diagnosis?

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

Correct Answer & Explanation

. Clear cell chondrosarcoma

Explanation

Clear cell chondrosarcoma is a rare, low-grade malignant cartilage tumor that typically occurs in the epiphysis of long bones in adults. Histologically, it features large cells with clear cytoplasm, which differentiates it from chondroblastoma.

Question 3862

Topic: 10. Pathology and Oncology

Which of the following histological features is the most reliable for distinguishing a low-grade conventional chondrosarcoma from a benign enchondroma?

. Presence of binucleated chondrocytes
. Hypercellularity of the cartilage matrix
. Permeation of the tumor through surrounding host lamellar bone
. Myxoid changes in the matrix
. Presence of calcification within the cartilage

Correct Answer & Explanation

. Permeation of the tumor through surrounding host lamellar bone

Explanation

The most reliable histological feature to differentiate low-grade chondrosarcoma from an enchondroma is the permeation of tumor cells into the surrounding normal host trabecular bone. Enchondromas typically have well-defined margins and do not trap or permeate native bony trabeculae.

Question 3863

Topic: 10. Pathology and Oncology

A 25-year-old male presents with multiple enchondromas predominantly affecting the right hand and leg, along with multiple soft-tissue venous malformations. What genetic mutation is most strongly associated with this condition, and what is the approximate risk of malignant transformation of the bone lesions?

. EXT1 mutation; <5% risk
. GNAS1 mutation; 10% risk
. IDH1 or IDH2 mutation; ~30-40% risk
. P53 mutation; >50% risk
. RUNX2 mutation; 1-5% risk

Correct Answer & Explanation

. IDH1 or IDH2 mutation; ~30-40% risk

Explanation

Maffucci syndrome is characterized by multiple enchondromas and soft-tissue hemangiomas, and is linked to somatic IDH1 or IDH2 mutations. Patients have a high risk of malignant transformation to chondrosarcoma (approximately 30-40%), as well as an increased risk of visceral malignancies.

Question 3864

Topic: 10. Pathology and Oncology

A 15-year-old male presents with a painless mass on the proximal humerus. Radiographs demonstrate a 2.5 cm surface lesion with underlying cortical saucerization and a sclerotic rim.

Biopsy is performed. Which of the following histologic features is characteristic of this lesion and must not be overinterpreted as malignancy?

. High cellularity and binucleate cells
. "Chicken-wire" calcifications with multinucleated giant cells
. Permeation into the underlying medullary canal
. Spindle cells in a storiform pattern
. Lace-like osteoid production by atypical cells

Correct Answer & Explanation

. High cellularity and binucleate cells

Explanation

Periosteal (juxtacortical) chondromas often exhibit high cellularity, mild pleomorphism, and binucleate cells. In a small surface lesion (<3 cm) with an intact sclerotic cortex, these features represent a benign periosteal chondroma and should not be mistaken for low-grade chondrosarcoma.

Question 3865

Topic: 10. Pathology and Oncology

A 22-year-old woman presents with chronic, dull pain in her proximal leg. Radiographs reveal an eccentric, heavily scalloped, lytic metaphyseal lesion in the proximal tibia with a distinct sclerotic rim. There is no matrix calcification. What is the most appropriate definitive treatment for this condition?

. Observation with serial radiographs
. Extended intralesional curettage with high-speed burring and bone grafting
. Wide en bloc resection
. Preoperative radiotherapy followed by marginal excision
. Radiofrequency ablation

Correct Answer & Explanation

. Extended intralesional curettage with high-speed burring and bone grafting

Explanation

Chondromyxoid fibroma (CMF) is a rare benign cartilage tumor presenting as an eccentric, scalloped metaphyseal lesion. The standard of care is extended intralesional curettage with adjuvant treatment (e.g., high-speed burr) and bone grafting due to a high local recurrence risk with simple curettage alone.

Question 3866

Topic: Bone Tumors

A 35-year-old man presents with a hard mass on the distal femur. Imaging shows a 6 cm lobulated surface mass with dense ring-and-arc calcifications. The lesion is elevating the periosteum but the underlying cortex is intact without medullary involvement.

What radiographic feature most strongly differentiates this from a periosteal chondroma?

. Intact underlying cortex
. Presence of ring-and-arc calcification
. Lack of medullary involvement
. Size of the lesion > 3 cm
. Soft tissue extension

Correct Answer & Explanation

. Size of the lesion > 3 cm

Explanation

Periosteal chondromas and periosteal chondrosarcomas both occur on the bone surface with an intact cortex and absent medullary involvement. A primary differentiating factor is size; lesions greater than 3 cm are highly suspicious for periosteal chondrosarcoma.

Question 3867

Topic: 10. Pathology and Oncology

A 40-year-old patient undergoes an MRI for a suspected meniscal tear. An incidental intramedullary lesion is found in the distal femur. It demonstrates a serpentine, well-demarcated border with a low-signal rim on both T1 and T2 sequences. How is this lesion radiographically distinct from an enchondroma?

. Enchondromas typically display "popcorn" calcifications rather than a serpentine sclerotic border.
. Enchondromas show low signal on T2-weighted MRI, unlike this lesion.
. This lesion is typical of fibrous dysplasia, which has a ground-glass appearance on X-ray.
. This lesion requires immediate biopsy to rule out dedifferentiated chondrosarcoma.
. Enchondromas typically expand the bone cortex circumferentially.

Correct Answer & Explanation

. Enchondromas typically display "popcorn" calcifications rather than a serpentine sclerotic border.

Explanation

The MRI description of a serpentine border with a low-signal rim is classic for a bone infarct. In contrast, enchondromas typically present as lobulated hyperintense lesions on T2 MRI with stippled, "popcorn" or rings-and-arcs matrix calcifications on radiographs.

Question 3868

Topic: 10. Pathology and Oncology

A 55-year-old male presents with worsening thigh pain. Biopsy of a proximal femur lesion reveals a bimorphic histological pattern showing a low-grade hyaline cartilage tumor abruptly juxtaposed with a high-grade spindle cell sarcoma. Which of the following is the most likely diagnosis?

. Mesenchymal chondrosarcoma
. Clear cell chondrosarcoma
. Dedifferentiated chondrosarcoma
. Osteosarcoma
. Chondroblastoma

Correct Answer & Explanation

. Dedifferentiated chondrosarcoma

Explanation

Dedifferentiated chondrosarcoma classically presents with a low-grade cartilage tumor adjacent to a highly malignant, non-cartilaginous spindle cell sarcoma. This abrupt transition is the histological hallmark and portends a very poor prognosis.

Question 3869

Topic: 10. Pathology and Oncology

A 45-year-old male presents with chronic, mild hip pain. Radiographs reveal a lytic lesion in the epiphysis of the proximal femur. Histological examination shows large cells with distinct borders, abundant clear cytoplasm, and interspersed woven bone. What is the diagnosis?

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

Correct Answer & Explanation

. Clear cell chondrosarcoma

Explanation

Clear cell chondrosarcoma is a low-grade malignant tumor that classically occurs in the epiphysis of long bones in adults (30-50 years). Although chondroblastoma is also epiphyseal, it typically occurs in skeletally immature patients and lacks the abundant clear cytoplasm seen here.

Question 3870

Topic: 10. Pathology and Oncology

A 16-year-old male undergoes curettage and bone grafting for an epiphyseal lesion in the proximal humerus. Histopathology reveals mononuclear cells with clefted, "coffee-bean" nuclei and areas of fine, pericellular "chicken-wire" calcification. Despite its benign nature, what complication must be monitored for?

. Leukemic transformation
. Pulmonary metastasis
. Skip lesions within the same bone
. Hypercalcemia
. Renal failure

Correct Answer & Explanation

. Pulmonary metastasis

Explanation

The histology describes a chondroblastoma. Though considered benign, chondroblastomas have a recognized potential (1-2%) to metastasize to the lungs.

Question 3871

Topic: Bone Tumors

A 24-year-old female presents with a painless, eccentric, expansile metaphyseal lesion in her proximal tibia. Histopathology demonstrates a lobular architecture with stellate and spindle cells embedded in a myxoid background, with multinucleated giant cells clustered at the lobular peripheries. What is the most likely diagnosis?

. Non-ossifying fibroma
. Aneurysmal bone cyst
. Chondromyxoid fibroma
. Myxoid chondrosarcoma
. Chondroblastoma

Correct Answer & Explanation

. Chondromyxoid fibroma

Explanation

Chondromyxoid fibroma typically presents as an eccentric metaphyseal lesion in young adults. Its classic histology features lobules of myxoid tissue containing stellate cells, with giant cells localized at the periphery of these lobules.

Question 3872

Topic: 10. Pathology and Oncology

A 30-year-old male presents with a destructive lesion in the mandible. Biopsy reveals a bimorphic pattern consisting of islands of well-differentiated hyaline cartilage surrounded by sheets of highly cellular, undifferentiated small round blue cells with hemangiopericytoma-like vessels. What is the diagnosis?

. Mesenchymal chondrosarcoma
. Ewing sarcoma
. Dedifferentiated chondrosarcoma
. Osteosarcoma
. Multiple myeloma

Correct Answer & Explanation

. Mesenchymal chondrosarcoma

Explanation

Mesenchymal chondrosarcoma is an aggressive tumor often found in the jaw, spine, or ribs. Its hallmark is a bimorphic histological appearance featuring cartilage islands intermixed with small round blue cells and staghorn vasculature.

Question 3873

Topic: Bone Tumors

A 14-year-old boy with multiple hemangiomas and venous malformations is found to have multiple asymmetric cartilaginous lesions in his hands and long bones. He is diagnosed with Maffucci syndrome. Compared to Ollier disease, he is at an inherently higher risk for which of the following?

. Retinoblastoma
. Astrocytoma and gastrointestinal malignancies
. Multiple myeloma
. Osteosarcoma
. Thyroid carcinoma

Correct Answer & Explanation

. Astrocytoma and gastrointestinal malignancies

Explanation

Maffucci syndrome is characterized by multiple enchondromas and vascular malformations. In addition to a near 100% risk of chondrosarcoma, these patients have a significantly higher risk of extraskeletal malignancies, notably astrocytomas and GI tract carcinomas, compared to Ollier disease.

Question 3874

Topic: 10. Pathology and Oncology

In evaluating an intramedullary cartilaginous lesion of the proximal humerus, which of the following clinical or radiographic features is the most reliable indicator of malignant transformation to a chondrosarcoma?

. Patient age over 30 years
. Presence of "popcorn" calcifications
. Deep, unrelenting pain in the absence of fracture
. Lesion size greater than 2 cm
. Lobulated T2 hyperintensity on MRI

Correct Answer & Explanation

. Deep, unrelenting pain in the absence of fracture

Explanation

In the absence of a fracture or other mechanical cause, new or unrelenting rest pain in a previously asymptomatic cartilaginous lesion is the most sensitive and reliable clinical indicator of malignant transformation to chondrosarcoma.

Question 3875

Topic: 10. Pathology and Oncology

An asymptomatic 45-year-old male has an incidental finding on a hand radiograph.

The image shows a well-circumscribed, central lucent lesion in the proximal phalanx with focal stippled calcifications. No cortical destruction is noted. What is the recommended management?

. Immediate wide resection
. Core needle biopsy
. Serial observation with clinical and radiographic follow-up
. Intralesional steroid injection
. Prophylactic internal fixation

Correct Answer & Explanation

. Serial observation with clinical and radiographic follow-up

Explanation

The image demonstrates a classic benign enchondroma of the hand. For an asymptomatic, structurally sound enchondroma without concerning features, the standard of care is serial clinical and radiographic observation.

Question 3876

Topic: 10. Pathology and Oncology

A 50-year-old male with a known history of multiple hereditary exostoses (MHE) reports rapid growth of a previously stable osteochondroma on his pelvis. On MRI, what cartilage cap thickness threshold is most highly suspicious for secondary chondrosarcoma in an adult?

. > 0.5 cm
. > 1.0 cm
. > 2.0 cm
. < 1.0 cm
. Any presence of an uncalcified cap

Correct Answer & Explanation

. > 2.0 cm

Explanation

In skeletally mature adults, a cartilage cap thickness greater than 2.0 cm on MRI or CT is highly suspicious for malignant transformation of an osteochondroma to a secondary chondrosarcoma.

Question 3877

Topic: 10. Pathology and Oncology

Primary chondrosarcoma most frequently arises in which of the following anatomic locations, which also happens to present significant surgical challenges and carries a poorer prognosis?

. Distal femur
. Proximal humerus
. Pelvis
. Hands and feet
. Skull base

Correct Answer & Explanation

. Pelvis

Explanation

The pelvis is the most common anatomic site for primary chondrosarcoma. Because these tumors often grow quite large before detection and are difficult to resect with wide margins in the pelvis, they generally carry a poorer prognosis.

Question 3878

Topic: 10. Pathology and Oncology

A 50-year-old male is diagnosed with an Atypical Cartilaginous Tumor (Grade 1 Chondrosarcoma) confined within the medullary canal of the proximal femur, without cortical breakthrough. Which surgical treatment strategy is currently favored for this specific presentation?

. Amputation
. Wide en bloc resection with massive endoprosthesis
. Extended intralesional curettage with local adjuvant application
. Palliative radiation therapy
. Preoperative chemotherapy followed by marginal excision

Correct Answer & Explanation

. Extended intralesional curettage with local adjuvant application

Explanation

For central atypical cartilaginous tumors (Grade 1 chondrosarcomas) of the long bones without cortical destruction, extended intralesional curettage with high-speed burring and local adjuvants (e.g., phenol, cryotherapy) is increasingly favored over wide resection, demonstrating low recurrence rates and superior functional outcomes.

Question 3879

Topic: 10. Pathology and Oncology

Histological evaluation of a curettage specimen from a benign hand enchondroma is most likely to demonstrate which of the following?

. Abundant hyaline cartilage with distinct single small nuclei and no atypia
. Binucleated chondrocytes in multiple lacunae with marked pleomorphism
. Spindle cells arranged in a herringbone pattern
. Multinucleated giant cells interspersed with mononuclear stromal cells
. Osteoid production directly from malignant cartilage cells

Correct Answer & Explanation

. Abundant hyaline cartilage with distinct single small nuclei and no atypia

Explanation

Benign enchondromas consist of lobules of mature hyaline cartilage. The chondrocytes reside in well-defined lacunae with small, single, uniform nuclei and lack significant atypia, hypercellularity, or prominent binucleation.

Question 3880

Topic: 10. Pathology and Oncology

A patient with a presumed cartilaginous bone tumor undergoes molecular testing, revealing an H3F3B (Histone H3.3) mutation. This finding is virtually pathognomonic for which of the following tumors?

. Enchondroma
. Chondroblastoma
. Chondromyxoid fibroma
. Clear cell chondrosarcoma
. Mesenchymal chondrosarcoma

Correct Answer & Explanation

. Chondroblastoma

Explanation

Mutations in the H3F3B gene are highly specific to chondroblastoma (found in up to 95% of cases). In contrast, H3F3A mutations are classically seen in giant cell tumors of bone.

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