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10. Pathology and Oncology MCQs

Practice Set 57 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 1121

Topic: 10. Pathology and Oncology

A 35-year-old male presents with mechanical elbow locking and decreased range of motion. Radiographs show multiple, uniform, intra-articular calcified loose bodies. He undergoes arthroscopic removal. The underlying pathophysiology of this specific condition most likely involves:

. Fragmentation of osteophytes from end-stage osteoarthritis
. Synovial metaplasia resulting in cartilaginous nodule formation
. Repetitive microtrauma to the central capitellar articular cartilage
. Septic destruction of the joint space
. Avulsion fractures of the medial epicondyle

Correct Answer & Explanation

. Synovial metaplasia resulting in cartilaginous nodule formation

Explanation

Primary synovial chondromatosis is a benign condition characterized by synovial metaplasia leading to the formation of multiple cartilaginous nodules that may calcify or ossify. It typically presents with mechanical symptoms and uniform loose bodies on imaging.

Question 1122

Topic: 10. Pathology and Oncology

A 35-year-old man presents with chronic multiple loose bodies in the elbow, causing intermittent locking and restricted range of motion. Radiographs show numerous calcified bodies of similar shape and size scattered throughout the joint. A biopsy of the synovium demonstrates metaplasia of synovial tissue into cartilaginous nodules. What is the most likely diagnosis?

. Osteoarthritis with loose bodies
. Primary synovial chondromatosis
. Pigmented villonodular synovitis (PVNS)
. Advanced osteochondritis dissecans
. Rheumatoid arthritis

Correct Answer & Explanation

. Primary synovial chondromatosis

Explanation

Primary synovial chondromatosis is a benign neoplastic process characterized by synovial metaplasia, producing numerous cartilaginous nodules that may detach and ossify. This typically presents as multiple uniform loose bodies throughout the joint.

Question 1123

Topic: 10. Pathology and Oncology

A 55-year-old male presents with persistent, dull pain in his proximal humerus. Radiographs reveal a lytic lesion with punctate and ring-and-arc calcifications, and cortical thickening without clear periosteal reaction. MRI shows a lobulated mass with high signal on T2-weighted images and internal septations enhancing after gadolinium. Core needle biopsy confirms low-grade chondrosarcoma. What is the most appropriate initial surgical management strategy?

. Intralesional curettage with adjuvant cryotherapy or phenol.
. Marginal excision with bone grafting.
. Wide en bloc resection.
. Amputation.
. Percutaneous radiofrequency ablation.

Correct Answer & Explanation

. Wide en bloc resection.

Explanation

Correct Answer: CFor a confirmed low-grade chondrosarcoma, especially in a long bone like the humerus, the standard of care iswide en bloc resection. Intralesional curettage carries a high risk of local recurrence due to the infiltrative nature of chondrosarcomas, even low-grade ones, and the difficulty in achieving clear margins intralesionally. Marginal excision may be considered for juxtacortical or surface lesions but is less appropriate for intramedullary lesions. Amputation is generally reserved for extensive, high-grade tumors where limb salvage is not feasible. Radiofrequency ablation is not an established primary treatment for chondrosarcoma.

Question 1124

Topic: 10. Pathology and Oncology

Which of the following histological features is most indicative of a conventional chondrosarcoma over an enchondroma?

. Presence of cartilaginous matrix.
. Absence of hematopoietic marrow.
. Hypercellularity with plump nuclei and occasional binucleation.
. Peripheral endochondral ossification.
. Presence of necrosis.

Correct Answer & Explanation

. Hypercellularity with plump nuclei and occasional binucleation.

Explanation

Correct Answer: CWhile cartilaginous matrix is present in both, and hematopoietic marrow is absent in both lesions,hypercellularity with plump nuclei and occasional binucleationis a key histological feature distinguishing low-grade chondrosarcoma from enchondroma. Enchondromas typically have bland, sparsely cellular cartilage. Necrosis, while seen in higher-grade chondrosarcomas, is not typically a feature of low-grade tumors and its presence is concerning for higher grade. Peripheral endochondral ossification can be seen in both, especially in benign lesions.

Question 1125

Topic: 10. Pathology and Oncology

A 70-year-old patient presents with a rapidly enlarging, painful mass in the distal femur. Imaging reveals an aggressive lytic lesion with cortical destruction and a soft tissue component. Biopsy shows areas of conventional chondrosarcoma juxtaposed with high-grade pleomorphic spindle cell sarcoma. What is the most likely diagnosis?

. High-grade conventional chondrosarcoma.
. Mesenchymal chondrosarcoma.
. Dedifferentiated chondrosarcoma.
. Clear cell chondrosarcoma.
. Chondroblastic osteosarcoma.

Correct Answer & Explanation

. Dedifferentiated chondrosarcoma.

Explanation

Correct Answer: CThe presence of a conventional chondrosarcoma component adjacent to a high-grade, non-cartilaginous sarcoma (e.g., undifferentiated pleomorphic sarcoma or osteosarcoma-like component) is pathognomonic fordedifferentiated chondrosarcoma. This variant typically presents in older patients with rapid growth and aggressive behavior. Mesenchymal chondrosarcoma is characterized by small, round blue cells and islands of hyaline cartilage. Clear cell chondrosarcoma is a low-grade tumor with distinctive clear cells, typically found in epiphyses. High-grade conventional chondrosarcoma would primarily show high-grade cartilaginous features throughout. Chondroblastic osteosarcoma would show osteoid production by malignant cells.

Question 1126

Topic: 10. Pathology and Oncology

Which of the following pre-existing conditions has the highest risk of malignant transformation to a secondary conventional chondrosarcoma?

. Solitary enchondroma.
. Multiple hereditary exostoses (MHE).
. Solitary osteochondroma.
. Synovial chondromatosis.
. Chondroblastoma.

Correct Answer & Explanation

. Multiple hereditary exostoses (MHE).

Explanation

Correct Answer: BMultiple hereditary exostoses (MHE), also known as hereditary multiple osteochondromas, carries the highest risk of malignant transformation among the listed options, with rates reported between 5-25% (some sources up to 30%) for an osteochondroma within the syndrome. Solitary enchondromas have a very low transformation rate (<1%), whereas enchondromas in syndromes like Ollier's disease or Maffucci's syndrome have a higher, but still lower than MHE, risk. Solitary osteochondromas have a malignant transformation rate of approximately 1%. Synovial chondromatosis and chondroblastoma are benign lesions with extremely rare or no documented malignant transformation to chondrosarcoma, respectively.

Question 1127

Topic: 10. Pathology and Oncology

A 40-year-old male with Ollier's disease presents with increasing pain in his distal femur. Radiographs show a large intramedullary lesion with aggressive features. Biopsy reveals a Grade II chondrosarcoma. Which of the following statements regarding the genetics of this patient's condition is most accurate?

. It is primarily associated with mutations in the EXT1 or EXT2 genes.
. It is typically linked to somatic mutations in IDH1 or IDH2 genes.
. It is an autosomal dominant disorder.
. It primarily involves a germline mutation in the TP53 gene.
. It is associated with mutations in the COL2A1 gene.

Correct Answer & Explanation

. It is typically linked to somatic mutations in IDH1 or IDH2 genes.

Explanation

Correct Answer: BOllier's disease and Maffucci's syndrome are non-hereditary, sporadic disorders characterized by multiple enchondromas (and hemangiomas in Maffucci's). They are primarily associated withsomatic mutations in the IDH1 or IDH2 genes, which are also frequently found in solitary enchondromas and conventional chondrosarcomas. EXT1/EXT2 mutations are associated with Multiple Hereditary Exostoses (MHE). TP53 is associated with Li-Fraumeni syndrome. COL2A1 is associated with various skeletal dysplasias, but not directly with Ollier's or Maffucci's disease transformation risk to chondrosarcoma.

Question 1128

Topic: 10. Pathology and Oncology

What is the primary role of systemic chemotherapy in the treatment of conventional chondrosarcoma?

. Adjuvant therapy for all high-grade tumors.
. Neoadjuvant therapy to downstage primary tumors.
. Palliative treatment for unresectable or metastatic disease.
. Primary treatment for mesenchymal chondrosarcoma.
. Primary treatment for low-grade tumors.

Correct Answer & Explanation

. Palliative treatment for unresectable or metastatic disease.

Explanation

Correct Answer: CConventional chondrosarcoma is notoriously resistant to conventional chemotherapy due to its relatively hypocellular and avascular nature. Therefore, systemic chemotherapy has a very limited role. It may be considered forpalliative treatment in cases of unresectable or metastatic disease, but its efficacy is generally poor. Chemotherapy is, however, an important component in the treatment of mesenchymal chondrosarcoma (due to its small round cell component) and dedifferentiated chondrosarcoma (due to the high-grade non-cartilaginous component), but this question specifically asks about 'conventional chondrosarcoma'.

Question 1129

Topic: 10. Pathology and Oncology

A 35-year-old patient presents with a lesion in the epiphysis of the proximal tibia. Radiographs show a lytic lesion with ill-defined margins and punctate calcifications. Biopsy reveals a tumor composed of epithelioid-like chondrocytes with clear cytoplasm, typically arranged in lobules, with prominent reactive bone formation at the periphery. What is the most likely diagnosis?

. Conventional chondrosarcoma, Grade I.
. Clear cell chondrosarcoma.
. Chondroblastoma.
. Osteosarcoma, chondroblastic type.
. Giant cell tumor of bone.

Correct Answer & Explanation

. Clear cell chondrosarcoma.

Explanation

Correct Answer: BThe description of a lytic epiphyseal lesion with epithelioid-like chondrocytes with clear cytoplasm and reactive bone formation at the periphery is classic forclear cell chondrosarcoma. Chondroblastoma is also epiphyseal but typically has polygonal cells with distinct cell membranes and often multinucleated giant cells. Conventional chondrosarcoma usually occurs in the metaphysis or diaphysis. Chondroblastic osteosarcoma is highly aggressive and shows malignant osteoid. Giant cell tumor lacks cartilaginous differentiation.

Question 1130

Topic: 10. Pathology and Oncology

Which of the following surgical margins is generally considered curative for a low-grade (Grade I) conventional chondrosarcoma of the appendicular skeleton, assuming no cortical breach?

. Intralesional.
. Marginal.
. Wide.
. Radical.
. Contaminant.

Correct Answer & Explanation

. Marginal.

Explanation

Correct Answer: BWhile wide excision is the gold standard for most chondrosarcomas, some low-grade (Grade I) conventional chondrosarcomas that are well-contained within the bone and have no cortical breach can potentially be cured with amarginal excision, where the tumor is removed with a rim of healthy tissue. However, this is a nuanced decision often requiring careful intraoperative assessment and frozen sections. Intralesional curettage alone is associated with higher recurrence rates even for low-grade lesions. Wide is always preferred if anatomically feasible. Radical implies removal of the entire compartment, which is usually for very high-grade or extensive lesions. Contaminant is not a surgical margin definition.

Question 1131

Topic: 10. Pathology and Oncology

A 60-year-old patient undergoes an en bloc resection for a Grade II chondrosarcoma of the proximal tibia. What is the most critical prognostic factor for local recurrence and survival in this patient?

. Patient's age.
. Tumor size.
. Presence of IDH1 mutation.
. Adequacy of surgical margins.
. Histological subtype.

Correct Answer & Explanation

. Adequacy of surgical margins.

Explanation

Correct Answer: DFor resectable chondrosarcoma, theadequacy of surgical marginsis the single most critical prognostic factor for both local recurrence and overall survival. Positive surgical margins are strongly associated with higher recurrence rates and poorer outcomes. While tumor size, patient age, histological subtype, and IDH mutations can also have prognostic implications, achieving clear surgical margins is paramount in preventing local disease progression and subsequent metastasis.

Question 1132

Topic: 10. Pathology and Oncology

A lesion is identified in the sacrum of a 45-year-old male. Biopsy confirms chondrosarcoma. What characteristic features might be seen on MRI that distinguish it from a chordoma, which can also occur in the sacrum?

. Predominantly T1 hypointense and T2 hyperintense signal.
. Presence of calcifications.
. Extension into the pre-sacral space.
. Lobulated morphology.
. Intralesional hemorrhage.

Correct Answer & Explanation

. Presence of calcifications.

Explanation

Correct Answer: BBoth chondrosarcoma and chordoma can occur in the sacrum and can be T1 hypointense and T2 hyperintense, and can show lobulated morphology and pre-sacral extension. However, thepresence of calcificationsis a key distinguishing feature of chondrosarcoma, reflecting the cartilaginous matrix. Chordomas rarely calcify. While intralesional hemorrhage can occur in any tumor, it's not a primary distinguishing feature between these two.

Question 1133

Topic: 10. Pathology and Oncology

A 62-year-old female presents with a destructive lesion in the proximal femur. Imaging shows a heavily calcified cartilaginous lesion contiguous with a highly aggressive, uncalcified lytic component destroying the cortex. What is the most likely diagnosis?

. Clear cell chondrosarcoma
. Mesenchymal chondrosarcoma
. Dedifferentiated chondrosarcoma
. Metastatic breast carcinoma
. Chondroblastic osteosarcoma

Correct Answer & Explanation

. Dedifferentiated chondrosarcoma

Explanation

Dedifferentiated chondrosarcoma typically presents as a low-grade cartilaginous lesion juxtaposed with a high-grade, non-cartilaginous sarcoma, giving a "bimorphic" appearance on imaging. It carries a poor prognosis and requires aggressive surgical treatment.

Question 1134

Topic: 10. Pathology and Oncology

A 45-year-old male presents with chronic shoulder pain. Radiographs reveal a lytic lesion in the epiphysis of the proximal humerus. Biopsy shows large cells with abundant clear cytoplasm and central nuclei, interspersed with trabecular bone and chondroid matrix. What is the most likely diagnosis?

. Chondroblastoma
. Clear cell chondrosarcoma
. Giant cell tumor of bone
. Aneurysmal bone cyst
. Enchondroma

Correct Answer & Explanation

. Clear cell chondrosarcoma

Explanation

Clear cell chondrosarcoma is a rare, low-grade epiphyseal lesion typically affecting adults (30-50 years). This distinguishes it from chondroblastoma, which typically affects skeletally immature patients in similar epiphyseal locations.

Question 1135

Topic: 10. Pathology and Oncology

A 28-year-old male with Multiple Hereditary Exostoses presents with a newly enlarging mass on his distal femur. MRI reveals a sessile osteochondroma with a cartilage cap thickness of 2.5 cm. What is the most appropriate management?

. Observation with serial MRIs in 6 months
. Intralesional curettage and bone grafting
. Wide surgical resection
. Neoadjuvant chemotherapy followed by excision
. Primary radiation therapy

Correct Answer & Explanation

. Wide surgical resection

Explanation

In adults, a cartilage cap thicker than 1.5-2.0 cm on MRI is highly suspicious for malignant transformation to secondary peripheral chondrosarcoma. Conventional chondrosarcomas are resistant to chemotherapy and radiation, making wide surgical resection the standard of care.

Question 1136

Topic: 10. Pathology and Oncology

A 55-year-old male sustains a midshaft femur fracture after a minor fall. Radiographs show a transverse fracture through a permeative lytic lesion with stippled calcifications. What is the most appropriate next step in management?

. Immediate reamed intramedullary nailing
. Open reduction and internal fixation with plates
. Closed reduction and casting
. Core needle biopsy prior to any definitive fixation
. Prophylactic radiation therapy to the femur

Correct Answer & Explanation

. Core needle biopsy prior to any definitive fixation

Explanation

In a pathologic fracture suspected to be a primary bone sarcoma (such as chondrosarcoma), biopsy must be performed before definitive fixation to avoid contaminating the medullary canal. Intramedullary nailing is strictly contraindicated for suspected primary bone sarcomas.

Question 1137

Topic: Bone Tumors

Which subtype of chondrosarcoma is characterized histologically by a "biphasic" pattern of highly cellular areas of small, round blue cells admixed with islands of well-differentiated hyaline cartilage, and is known to be responsive to chemotherapy and radiation?

. Conventional chondrosarcoma
. Dedifferentiated chondrosarcoma
. Clear cell chondrosarcoma
. Mesenchymal chondrosarcoma
. Secondary peripheral chondrosarcoma

Correct Answer & Explanation

. Mesenchymal chondrosarcoma

Explanation

Mesenchymal chondrosarcoma is a rare, highly aggressive subtype presenting with a biphasic histology of small blue cells and cartilage. Unlike conventional chondrosarcoma, it is often sensitive to adjuvant chemotherapy and radiation.

Question 1138

Topic: 10. Pathology and Oncology

A 30-year-old female with multiple enchondromas and soft tissue hemangiomas presents with increasing pain in her proximal tibia. Biopsy confirms secondary chondrosarcoma. Which genetic mutation is most commonly associated with her underlying syndrome?

. EXT1
. IDH1
. GNAS
. RB1
. TP53

Correct Answer & Explanation

. IDH1

Explanation

The patient has Maffucci syndrome, characterized by multiple enchondromas and soft tissue hemangiomas. Enchondromatosis syndromes (Ollier and Maffucci) are strongly associated with somatic mutations in the IDH1 and IDH2 genes.

Question 1139

Topic: 10. Pathology and Oncology

A 65-year-old male is diagnosed with a grade II conventional chondrosarcoma of the right ilium with cortical breakthrough. What is the most appropriate definitive management?

. Intralesional curettage, burring, and cementation
. Wide local excision with negative margins
. Primary radiation therapy followed by curettage
. Neoadjuvant chemotherapy followed by wide excision
. Radiofrequency ablation

Correct Answer & Explanation

. Wide local excision with negative margins

Explanation

Grade II conventional chondrosarcomas have significant metastatic potential and high local recurrence rates if not resected entirely. Wide local excision with negative margins is the gold standard, especially in the pelvis where recurrence is difficult to manage.

Question 1140

Topic: 10. Pathology and Oncology

A 40-year-old asymptomatic male is found incidentally to have a 4 cm intramedullary lesion with popcorn calcifications in his distal femur. MRI shows no cortical breakthrough or soft tissue extension. Biopsy confirms an atypical cartilaginous tumor (Grade I chondrosarcoma). What is the preferred treatment?

. Wide en bloc resection and endoprosthetic reconstruction
. Amputation
. Extended intralesional curettage and local adjuvant therapy
. Definitive radiation therapy
. Systemic chemotherapy

Correct Answer & Explanation

. Extended intralesional curettage and local adjuvant therapy

Explanation

Atypical cartilaginous tumors (Grade I chondrosarcoma) in the appendicular skeleton are commonly treated with extended intralesional curettage and local adjuvants (e.g., burring, phenol, cryotherapy). This preserves bone stock while maintaining excellent local control rates.

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