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10. Pathology and Oncology MCQs

Practice Set 258 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 5141

Topic: Bone Tumors

Which of the following is considered the most common site for conventional chondrosarcoma?

. Small bones of the hands and feet.
. Distal femur and proximal tibia.
. Pelvis and proximal femur.
. Vertebrae.
. Ribs.

Correct Answer & Explanation

. Pelvis and proximal femur.

Explanation

The pelvis and proximal femur are the most common sites for conventional chondrosarcoma, accounting for a significant proportion of cases. While chondrosarcoma can occur in any bone, including small bones, vertebrae, ribs, and long bones, the large flat bones of the pelvis and proximal long bones are classic locations.

Question 5142

Topic: 10. Pathology and Oncology

A 65-year-old patient with a large, asymptomatic pelvic lesion suspicious for chondrosarcoma is being evaluated. What is the definitive diagnostic procedure?

. CT scan of the pelvis.
. MRI with contrast.
. PET scan.
. Core needle biopsy.
. Bone scintigraphy.

Correct Answer & Explanation

. Core needle biopsy.

Explanation

While imaging (CT, MRI) is crucial for characterizing the lesion and surgical planning, the definitive diagnosis of chondrosarcoma (and all bone tumors) relies on histological examination via biopsy. A core needle biopsy is generally preferred over open biopsy to minimize contamination, especially for a pelvic lesion where surgical access can be challenging. Imaging studies are suggestive but not definitive. PET scans are used for staging and assessing metabolic activity, but not for definitive diagnosis. Bone scintigraphy can show increased uptake but is non-specific.

Question 5143

Topic: Bone Tumors

What is a key difference in the clinical presentation of an enchondroma versus a low-grade chondrosarcoma in an adult?

. Enchondromas are typically painful, while chondrosarcomas are not.
. Low-grade chondrosarcomas are often asymptomatic, while enchondromas usually cause fractures.
. Enchondromas commonly present with pathological fractures; low-grade chondrosarcomas present with localized pain.
. Enchondromas are typically asymptomatic unless complicated by fracture, whereas new or increasing pain in an adult is a red flag for chondrosarcoma.
. Both are typically painful from onset.

Correct Answer & Explanation

. Enchondromas are typically asymptomatic unless complicated by fracture, whereas new or increasing pain in an adult is a red flag for chondrosarcoma.

Explanation

Enchondromas are typically asymptomatic incidental findings unless they cause a pathological fracture. In contrast, new onset or increasing dull, persistent pain in an adult with a cartilaginous lesion, especially in a central location, is a classic warning sign for malignant transformation to chondrosarcoma, even low-grade. While low-grade chondrosarcomas can be asymptomatic initially, pain is a much more common presentation than with enchondromas, which only become painful with complications.

Question 5144

Topic: 10. Pathology and Oncology

A patient is found to have a conventional chondrosarcoma. Which of the following statements about its metastatic potential is true?

. Metastasis is common even in Grade I tumors.
. The most common site of metastasis is regional lymph nodes.
. Metastasis is primarily hematogenous, with the lungs being the most common site.
. Metastasis typically occurs early in the disease course.
. Metastasis is highly responsive to chemotherapy.

Correct Answer & Explanation

. Metastasis is primarily hematogenous, with the lungs being the most common site.

Explanation

Metastasis from conventional chondrosarcoma is primarily hematogenous, and the lungs are the most common site for metastatic disease. Regional lymph node metastasis is rare. Grade I tumors have a very low metastatic potential. Metastasis tends to occur later in the disease course, particularly with higher-grade tumors or after local recurrences. As previously noted, conventional chondrosarcoma metastases are generally chemoresistant.

Question 5145

Topic: 10. Pathology and Oncology

In the context of chondrosarcoma, what is the significance of IDH1/IDH2 mutations?

. They are oncogenic drivers and potential therapeutic targets, frequently found in conventional and dedifferentiated chondrosarcomas.
. They are tumor suppressor genes, and their inactivation leads to malignancy.
. They are primarily found in mesenchymal chondrosarcomas.
. They are genetic markers for differentiating enchondroma from chondrosarcoma, present only in benign lesions.
. They are associated with response to radiation therapy.

Correct Answer & Explanation

. They are oncogenic drivers and potential therapeutic targets, frequently found in conventional and dedifferentiated chondrosarcomas.

Explanation

Somatic mutations in isocitrate dehydrogenase 1 (IDH1) and IDH2 genes are frequently found in conventional central chondrosarcomas (up to 70%), dedifferentiated chondrosarcomas, and enchondromas (particularly in Ollier's and Maffucci's diseases). These mutations lead to the production of D-2-hydroxyglutarate (2HG), an oncometabolite, and are considered oncogenic drivers. They represent promising therapeutic targets for specific inhibitors. They are not tumor suppressor genes and are not exclusive to mesenchymal chondrosarcoma, nor are they exclusively found in benign lesions; their presence in enchondromas and low-grade chondrosarcomas highlights the continuum of cartilaginous tumor progression.

Question 5146

Topic: 10. Pathology and Oncology

A 48-year-old male presents with hip pain and a pelvic mass. Biopsy confirms Grade II chondrosarcoma. Surgical planning involves wide resection. Which of the following imaging modalities is most critical for assessing the extent of soft tissue involvement and neurovascular compromise in complex anatomical locations like the pelvis?

. Plain radiographs.
. CT scan with intravenous contrast.
. MRI with gadolinium contrast.
. Bone scintigraphy.
. PET-CT.

Correct Answer & Explanation

. MRI with gadolinium contrast.

Explanation

MRI with gadolinium contrast is the gold standard for assessing soft tissue involvement, defining tumor margins, evaluating neurovascular bundle involvement, and planning surgical approaches in complex anatomical regions like the pelvis for bone and soft tissue tumors. While CT provides excellent bony detail and calcification assessment, MRI is superior for soft tissue contrast. Plain radiographs are initial screening tools. Bone scintigraphy and PET-CT are useful for assessing metabolic activity and metastasis but are less precise for local anatomical detail and margin assessment.

Question 5147

Topic: Bone Tumors
Which histological subtype of chondrosarcoma is known for its relatively indolent course, often affecting the epiphyses of long bones, and may be confused with chondroblastoma?
. Dedifferentiated chondrosarcoma.
. Mesenchymal chondrosarcoma.
. Conventional chondrosarcoma (Grade III).
. Clear cell chondrosarcoma.
. Juxtacortical chondrosarcoma.

Correct Answer & Explanation

. Clear cell chondrosarcoma.

Explanation

Clear cell chondrosarcoma is a rare, low-grade variant typically found in the epiphyses of long bones (e.g., proximal humerus, distal femur, proximal tibia) of young to middle-aged adults. Its histological features (clear cells, reactive bone formation, often epiphyseal location) can lead to misdiagnosis as chondroblastoma. It has a relatively indolent course compared to other malignant chondrosarcoma types, but still requires wide excision.

Question 5148

Topic: 10. Pathology and Oncology

What is the primary reason conventional chondrosarcomas are generally considered radioresistant?

. They are highly vascular tumors.
. They have a low metabolic rate and low mitotic index.
. They are rapidly proliferating tumors.
. They produce a protective cartilaginous matrix that radiation cannot penetrate.
. They have high expression of DNA repair enzymes.

Correct Answer & Explanation

. They have a low metabolic rate and low mitotic index.

Explanation

Conventional chondrosarcomas are typically hypocellular and have a relatively low metabolic rate and low mitotic index compared to many other sarcomas. Radiation therapy is most effective against rapidly dividing cells. This inherent biological characteristic makes them relatively radioresistant. While DNA repair mechanisms contribute, the fundamental biological inertness of the chondrocytes within the tumor is the primary factor.

Question 5149

Topic: 10. Pathology and Oncology

A 58-year-old male with a history of a solitary osteochondroma on his scapula develops a rapidly growing, painful mass. Biopsy reveals features of both chondrosarcoma and undifferentiated pleomorphic sarcoma. What surgical consideration is paramount in this case?

. Marginal excision to preserve function.
. Intralesional curettage to remove the cartilaginous component.
. Wide en bloc resection with aggressive margins.
. Preoperative radiation therapy to shrink the tumor.
. Neoadjuvant chemotherapy to address the undifferentiated component.

Correct Answer & Explanation

. Wide en bloc resection with aggressive margins.

Explanation

The description of chondrosarcoma alongside an undifferentiated pleomorphic sarcoma component points to dedifferentiated chondrosarcoma. This is an extremely aggressive variant with a high propensity for metastasis and local recurrence. Therefore, wide en bloc resection with aggressive margins is paramount to achieve local control. Marginal excision or intralesional curettage would be grossly inadequate. While neoadjuvant chemotherapy may be considered for the undifferentiated component, surgical resection with clear margins remains the cornerstone of treatment. Radiation therapy is not typically curative for these lesions as a primary treatment.

Question 5150

Topic: 10. Pathology and Oncology

Which of the following conditions is most likely to be confused with a low-grade chondrosarcoma on imaging and biopsy, particularly in the short tubular bones?

. Osteochondroma.
. Giant cell tumor.
. Enchondroma.
. Fibrous dysplasia.
. Chondroblastoma.

Correct Answer & Explanation

. Enchondroma.

Explanation

Enchondroma is the most challenging differential diagnosis for low-grade chondrosarcoma, especially in the short tubular bones (hands and feet). The distinction can be particularly difficult on biopsy, requiring careful assessment of cellularity, nuclear atypia, and matrix patterns. Osteochondromas are exophytic lesions with a clear bony cortex. Giant cell tumors are typically epiphyseal/metaphyseal, lytic, and lack cartilaginous matrix. Fibrous dysplasia has a characteristic ground-glass matrix. Chondroblastoma is epiphyseal.

Question 5151

Topic: Bone Tumors
What is the defining characteristic of a low-grade (Grade I) conventional chondrosarcoma on histological examination?
. High mitotic activity and extensive necrosis.
. Marked cellular pleomorphism and prominent spindle cell component.
. Mildly increased cellularity with plump nuclei, occasional binucleation, and permeation of marrow spaces.
. Sheets of small, round blue cells with interspersed cartilage islands.
. Epithelioid cells with clear cytoplasm in an epiphyseal location.

Correct Answer & Explanation

. Mildly increased cellularity with plump nuclei, occasional binucleation, and permeation of marrow spaces.

Explanation

Grade I conventional chondrosarcoma is characterized by mildly increased cellularity compared to enchondroma, with plump nuclei, occasional binucleation, and a hallmark feature is the permeation of marrow fat spaces by tumor cells. High mitotic activity, necrosis, and marked pleomorphism are features of higher grades (II and III). Small round blue cells and cartilage islands define mesenchymal chondrosarcoma. Epithelioid clear cells define clear cell chondrosarcoma.

Question 5152

Topic: 10. Pathology and Oncology
Regarding chondrosarcoma staging, which system is most commonly used by orthopedic oncologists and provides prognostic information primarily based on tumor grade and local extent?
. TNM staging system (AJCC/UICC).
. Enneking Staging System (Musculoskeletal Tumor Society).
. Duke's staging system.
. Ann Arbor staging system.
. Federation Nationale des Centres de Lutte Contre le Cancer (FNCLCC) grading system.

Correct Answer & Explanation

. Enneking Staging System (Musculoskeletal Tumor Society).

Explanation

The Enneking Staging System (Musculoskeletal Tumor Society) is widely used by orthopedic oncologists for primary bone and soft tissue sarcomas. It classifies tumors based on grade (G), local extent (T, Intracapsular/Intracompartmental/Extracompartmental), and presence of metastasis (M). The TNM system (AJCC) is also used but the Enneking system specifically addresses the unique considerations of musculoskeletal sarcomas for surgical planning. Duke's is for colorectal cancer, Ann Arbor for lymphoma, and FNCLCC is a grading system primarily for soft tissue sarcomas.

Question 5153

Topic: 10. Pathology and Oncology

A 75-year-old male presents with persistent sacral pain. Imaging shows a large, destructive lesion in the sacrum with amorphous calcifications. Biopsy confirms Grade II chondrosarcoma. Due to the size and location, a complete en bloc resection would be highly morbid. What is a potential adjuvant therapy that might be considered if clear surgical margins are difficult to obtain?

. Standard fractionated external beam radiation therapy.
. High-dose systemic chemotherapy.
. Immunotherapy.
. Proton beam therapy or carbon ion therapy.
. Targeted therapy against IDH mutations.

Correct Answer & Explanation

. Proton beam therapy or carbon ion therapy.

Explanation

While conventional chondrosarcoma is generally radioresistant, advanced radiation techniques like proton beam therapy or carbon ion therapy offer superior dose conformity and allow for higher doses to be delivered to the tumor while sparing critical adjacent structures (like the spinal cord or bowel in sacral tumors). These can be considered, particularly in cases where complete surgical resection with clear margins is challenging or impossible. Standard fractionated external beam radiation has limited efficacy. Systemic chemotherapy and immunotherapy have limited roles for conventional chondrosarcoma. Targeted IDH inhibitors are emerging but are not yet standard adjuvant therapy and depend on specific mutations.

Question 5154

Topic: 10. Pathology and Oncology

Which of the following is characteristic of a mesenchymal chondrosarcoma?

. Predominantly affects elderly patients in the flat bones.
. Has a biphasic histology with small round cells and islands of hyaline cartilage.
. Is typically a low-grade tumor with excellent prognosis.
. Is resistant to both chemotherapy and radiation therapy.
. Usually presents in the epiphysis of long bones.

Correct Answer & Explanation

. Has a biphasic histology with small round cells and islands of hyaline cartilage.

Explanation

Mesenchymal chondrosarcoma is characterized by its distinct biphasic histology. It tends to affect younger patients (2nd-3rd decades), can occur in various locations including the axial skeleton and soft tissues, and is considered high-grade. Unlike conventional chondrosarcoma, it can be sensitive to chemotherapy and, to a lesser extent, radiation, due to its small round cell component. It does not typically present in the epiphysis.

Question 5155

Topic: Bone Tumors

A 30-year-old patient has a suspected chondrosarcoma in the femoral shaft. Which imaging characteristic on MRI would be most concerning for a high-grade lesion rather than a low-grade one?

. Endosteal scalloping of the cortex.
. Lobulated growth pattern with internal septa.
. Well-defined sclerotic border.
. Cortical destruction and extraosseous extension.
. Punctate calcifications within the matrix.

Correct Answer & Explanation

. Cortical destruction and extraosseous extension.

Explanation

Cortical destruction and extraosseous extension into surrounding soft tissues are hallmark signs of an aggressive, higher-grade chondrosarcoma. Endosteal scalloping, lobulated growth pattern, and punctate calcifications can be seen in both low-grade chondrosarcomas and even some enchondromas, though more pronounced scalloping and lobulation suggest malignancy. A well-defined sclerotic border is usually a feature of a benign lesion or a very indolent process, not a high-grade chondrosarcoma.

Question 5156

Topic: 10. Pathology and Oncology

Which of the following is NOT typically considered a primary treatment modality for resectable conventional chondrosarcoma?

. Wide surgical resection.
. Marginal surgical resection (in select low-grade cases).
. Intralesional curettage with adjuvant therapy (e.g., cryoablation) for specific low-grade lesions.
. Systemic chemotherapy.
. Amputation (for extensive disease).

Correct Answer & Explanation

. Systemic chemotherapy.

Explanation

Systemic chemotherapy has a very limited role in the primary treatment of resectable conventional chondrosarcoma due to its chemoresistance. The primary treatment modalities are surgical: wide resection is the gold standard, marginal resection may be considered for very select low-grade lesions, and intralesional curettage with adjuvants is sometimes used for specific low-grade central lesions in expendable bones. Amputation is reserved for extensive, high-grade, or recurrent tumors where limb salvage is not feasible. The question asks what is NOT typically considered primary treatment, making chemotherapy the correct answer.

Question 5157

Topic: 10. Pathology and Oncology

What is the typical prognosis for patients with dedifferentiated chondrosarcoma compared to conventional Grade I chondrosarcoma?

. Dedifferentiated chondrosarcoma has a significantly better prognosis.
. Both have similar excellent prognoses.
. Dedifferentiated chondrosarcoma has a significantly worse prognosis.
. Dedifferentiated chondrosarcoma has a better prognosis only if treated with chemotherapy.
. The prognosis is solely dependent on tumor size, not subtype.

Correct Answer & Explanation

. Dedifferentiated chondrosarcoma has a significantly worse prognosis.

Explanation

Dedifferentiated chondrosarcoma has a significantly worse prognosis than conventional Grade I chondrosarcoma. It is an aggressive, high-grade tumor with a high metastatic rate and poor overall survival, despite aggressive surgical and often systemic therapy. Conventional Grade I chondrosarcoma, if adequately resected, has an excellent prognosis with very low metastatic potential.

Question 5158

Topic: 10. Pathology and Oncology

A 40-year-old female presents with a slowly growing, painful mass in her chest wall. Imaging shows a rib lesion with chondroid matrix and cortical expansion. Biopsy confirms Grade II chondrosarcoma. What surgical principle is most important for local control in this patient?

. Achieving an intralesional margin to remove the bulk of the tumor.
. Performing a wide en bloc resection of the affected rib with clear margins.
. Debulking the tumor followed by radiation therapy.
. Administering neoadjuvant chemotherapy before surgery.
. Performing a marginal excision without bone reconstruction.

Correct Answer & Explanation

. Performing a wide en bloc resection of the affected rib with clear margins.

Explanation

For a Grade II chondrosarcoma of the rib, wide en bloc resection with clear margins is essential for local control. This typically involves removing the entire affected rib section, including surrounding soft tissue. Intralesional margins are inadequate and lead to high recurrence rates. Debulking followed by radiation is generally not effective for conventional chondrosarcoma. Neoadjuvant chemotherapy is not standard for conventional chondrosarcoma. Marginal excision might be considered for very low-grade, non-aggressive lesions, but for Grade II, wide margins are critical, and bone reconstruction is a separate consideration for stability.

Question 5159

Topic: 10. Pathology and Oncology

Which of the following syndromes is associated with an increased risk of multiple enchondromas and subsequent malignant transformation to chondrosarcoma, often presenting with soft tissue hemangiomas?

. Multiple Hereditary Exostoses (MHE).
. Li-Fraumeni syndrome.
. Ollier's disease.
. Maffucci's syndrome.
. Paget's disease of bone.

Correct Answer & Explanation

. Maffucci's syndrome.

Explanation

Maffucci's syndrome is characterized by the presence of multiple enchondromas (similar to Ollier's disease) and soft tissue spindle cell hemangiomas. Both Ollier's disease and Maffucci's syndrome carry a significant risk of malignant transformation of enchondromas into chondrosarcoma, with Maffucci's often cited as having a higher risk (20-50%). MHE is associated with osteochondromas. Li-Fraumeni is associated with various sarcomas and carcinomas (TP53 mutation). Paget's disease increases the risk of osteosarcoma, not chondrosarcoma primarily.

Question 5160

Topic: Bone Tumors

What is the typical age range for the presentation of conventional chondrosarcoma?

. Childhood (0-10 years).
. Adolescence (10-20 years).
. Young adults (20-40 years).
. Middle to older adulthood (40-70+ years).
. Any age, with no clear peak.

Correct Answer & Explanation

. Middle to older adulthood (40-70+ years).

Explanation

Conventional chondrosarcoma typically presents in middle to older adulthood, with a peak incidence in the 5th to 7th decades of life (40-70+ years). While it can occur in younger individuals, especially in the setting of syndromes like Ollier's or Maffucci's, it is rare in childhood and adolescence. Other variants like mesenchymal chondrosarcoma may affect younger populations.

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