Menu

10. Pathology and Oncology MCQs

Practice Set 263 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 5241

Topic: 10. Pathology and Oncology

A 35-year-old female presents with shoulder pain and a lesion in her proximal humerus. Radiographs show a lytic lesion with an 'O-ring' sign (sclerotic rim). MRI reveals heterogeneous signal intensity with internal calcifications. Biopsy demonstrates polygonal cells with clear cytoplasm and giant cells. What is the most likely diagnosis?

. Conventional central chondrosarcoma
. Chondroblastoma
. Clear cell chondrosarcoma
. Giant cell tumor of bone
. Aneurysmal bone cyst

Correct Answer & Explanation

. Clear cell chondrosarcoma

Explanation

The patient's age (younger than typical for conventional chondrosarcoma), epiphyseal location (proximal humerus epiphysis), 'O-ring' sign on X-ray, and biopsy findings of polygonal cells with clear cytoplasm and giant cells are highly characteristic of clear cell chondrosarcoma. While chondroblastoma can also occur in epiphyses and have giant cells, clear cell chondrosarcoma is the more appropriate diagnosis with clear cell features and less prominent chondroid matrix. Giant cell tumor lacks the chondroid features. Conventional chondrosarcoma typically presents in older patients and is medullary. Aneurysmal bone cyst is cystic.

Question 5242

Topic: 10. Pathology and Oncology

When assessing a potential chondrosarcoma, which imaging modality is best for evaluating cortical integrity and tumor mineralization?

. Magnetic Resonance Imaging (MRI)
. Computed Tomography (CT)
. Plain Radiographs
. Bone Scintigraphy (Technetium-99m)
. Ultrasound

Correct Answer & Explanation

. Computed Tomography (CT)

Explanation

Computed Tomography (CT) is superior to other modalities for evaluating cortical integrity (e.g., expansion, erosion, destruction) and precisely characterizing chondroid matrix calcifications. While plain radiographs are initial screening, CT offers much greater detail. MRI is excellent for soft tissue extension and marrow involvement but less precise for fine cortical changes and small calcifications. Bone scintigraphy assesses metabolic activity but not structural detail. Ultrasound has limited utility for intraosseous lesions.

Question 5243

Topic: Bone Tumors

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

. 0-10 years
. 10-20 years
. 20-30 years
. 30-60 years
. 70+ years

Correct Answer & Explanation

. 30-60 years

Explanation

Conventional central chondrosarcoma typically presents in adults, most commonly in the 3rd to 6th decades of life (30-60 years). It is rare in children and adolescents. While it can occur in older individuals, the peak incidence is within this range. Other variants like mesenchymal chondrosarcoma can occur in younger individuals.

Question 5244

Topic: 10. Pathology and Oncology

A patient with a presumed enchondroma develops local recurrence after intralesional curettage. Histopathology of the recurrent lesion shows increased cellularity, nuclear atypia, and mitotic activity compared to the initial biopsy. What does this suggest?

. The initial diagnosis was incorrect, and it was always a high-grade chondrosarcoma.
. The recurrent lesion is likely a dedifferentiated chondrosarcoma.
. The initial tumor was likely a low-grade chondrosarcoma that recurred due to inadequate excision.
. This is a benign recurrence, indicating a reactive process.
. The patient requires immediate systemic chemotherapy.

Correct Answer & Explanation

. The initial tumor was likely a low-grade chondrosarcoma that recurred due to inadequate excision.

Explanation

Recurrence of a presumed enchondroma after intralesional curettage with increased cellularity, nuclear atypia, and mitotic activity strongly suggests that the initial lesion was either a low-grade chondrosarcoma that recurred due to inadequate excision, or that the initial biopsy missed the malignant focus, or that the lesion underwent dedifferentiation. Given the description, it points to the initial lesion being a low-grade chondrosarcoma (which can be hard to differentiate from enchondroma) that recurred aggressively. While dedifferentiation is possible, simple recurrence of an inadequately treated low-grade lesion is more direct. However, the question asks what it 'suggests', and the change to higher grade features indicates it was not benign and suggests an upgrade in malignancy. Of the choices, it suggests that the original diagnosis was likely a low-grade chondrosarcoma that recurred. The increased aggressiveness points away from benign recurrence. Option C is the most accurate description of the situation given the recurrence and the histological changes.

Question 5245

Topic: Bone Tumors

What is the primary reason for the resistance of conventional chondrosarcoma to conventional chemotherapy and external beam radiation therapy?

. Rapid proliferation rate of chondrocytes
. Lack of specific growth factor receptors
. Poor vascularity and hypoxic environment of cartilage
. High expression of multi-drug resistance proteins
. Inability of drugs to penetrate the cartilaginous matrix

Correct Answer & Explanation

. Poor vascularity and hypoxic environment of cartilage

Explanation

The primary reason for chondrosarcoma's resistance to chemotherapy and radiation therapy is attributed to the inherent poor vascularity and hypoxic environment of cartilaginous tissue, which limits drug delivery and the effectiveness of radiation. Chondrosarcomas generally have a slow growth rate, and while multi-drug resistance proteins can play a role, the fundamental nature of cartilage is key.

Question 5246

Topic: Bone Tumors

Which of the following is typically a feature of Grade 1 conventional chondrosarcoma on histopathology?

. Prominent spindle cell component
. High cellularity with significant nuclear atypia and numerous mitotic figures
. Bland chondrocytes with small, uniform nuclei and rare mitotic figures, often with increased cellularity compared to enchondroma
. Areas of osteoid or bone formation within the cartilaginous matrix
. Large areas of necrosis

Correct Answer & Explanation

. Bland chondrocytes with small, uniform nuclei and rare mitotic figures, often with increased cellularity compared to enchondroma

Explanation

Grade 1 conventional chondrosarcoma is characterized by bland chondrocytes with small, uniform nuclei, often increased cellularity compared to an enchondroma, and rare or absent mitotic figures. It can be challenging to distinguish from enchondroma. Prominent spindle cells, high cellularity with significant atypia and mitoses, and necrosis are features of higher-grade chondrosarcomas or other sarcomas. Osteoid/bone formation would suggest osteosarcoma or dedifferentiated chondrosarcoma if it were an anaplastic component.

Question 5247

Topic: 10. Pathology and Oncology

A 58-year-old male undergoes routine chest X-ray and a solitary pulmonary nodule is discovered. He has a history of a resected Grade 2 conventional chondrosarcoma of the proximal tibia 3 years ago. What is the most appropriate next step in managing the pulmonary nodule?

. Biopsy the nodule immediately
. Observation with serial chest X-rays
. PET scan for metabolic activity
. High-resolution CT chest to characterize the nodule
. Empiric chemotherapy

Correct Answer & Explanation

. High-resolution CT chest to characterize the nodule

Explanation

Given the patient's history of Grade 2 chondrosarcoma, a solitary pulmonary nodule is highly suspicious for metastatic disease. A high-resolution CT chest is the most appropriate next step to fully characterize the nodule in terms of size, morphology, and number. This will help determine the likelihood of malignancy and guide subsequent management, which may include biopsy or surgical resection depending on the findings. PET scan can also be useful to assess metabolic activity but CT is usually first-line for detailed morphology. Observation is inappropriate. Biopsy is premature without full characterization. Empiric chemotherapy is not indicated without definitive diagnosis.

Question 5248

Topic: 10. Pathology and Oncology

Which anatomical location for a chondrosarcoma is associated with the worst prognosis?

. Proximal humerus
. Distal femur
. Proximal tibia
. Pelvis
. Small bones of the hand

Correct Answer & Explanation

. Pelvis

Explanation

Chondrosarcomas of the pelvis (and sacrum) are often large at presentation, can be difficult to diagnose early, and are challenging to resect with wide margins due to complex anatomy and proximity to vital neurovascular structures. This often leads to incomplete resections, high local recurrence rates, and ultimately a worse prognosis compared to tumors in more amenable appendicular sites. Small bones of the hand generally have a good prognosis as they are usually low-grade and easily resectable.

Question 5249

Topic: 10. Pathology and Oncology

What is the role of cryoablation or radiofrequency ablation in the treatment of chondrosarcoma?

. Primary treatment for all chondrosarcomas
. Effective for Grade 2 and 3 chondrosarcomas as a standalone therapy
. May be used as an adjuvant to intralesional curettage for low-grade, well-contained lesions
. Used primarily for metastatic disease to the lung
. Has no role in the management of chondrosarcoma

Correct Answer & Explanation

. May be used as an adjuvant to intralesional curettage for low-grade, well-contained lesions

Explanation

While surgical resection is the primary treatment, cryoablation or radiofrequency ablation can be used as an adjuvant therapy to intralesional curettage for low-grade (Grade 1), well-contained conventional chondrosarcomas to improve local control and reduce recurrence rates. These ablative techniques are not suitable as primary standalone treatments for higher-grade lesions or those with cortical breach/soft tissue extension, nor are they a primary treatment for metastatic lung disease (which typically involves surgical resection or systemic therapy if diffuse). Option 3 indicates it's useful for lung mets, which is incorrect. Option 2 states it's useful for Grade 2 and 3 as standalone, which is also incorrect. Option C is the correct answer.

Question 5250

Topic: 10. Pathology and Oncology

A 72-year-old female presents with a lesion in her calcaneus. Biopsy reveals clear cell chondrosarcoma. Compared to conventional chondrosarcoma, what is a key differentiating feature of clear cell chondrosarcoma in terms of prognosis and management?

. Higher rate of metastasis to regional lymph nodes
. Generally has a more aggressive clinical course and poorer prognosis
. Tends to occur in an older age group
. Metastasizes more commonly to the liver
. Lower metastatic potential but higher rate of local recurrence

Correct Answer & Explanation

. Lower metastatic potential but higher rate of local recurrence

Explanation

Clear cell chondrosarcoma is generally considered a low-grade malignant tumor with a lower metastatic potential compared to high-grade conventional chondrosarcoma, but it has a relatively high rate of local recurrence due to its often infiltrative nature and challenging locations (e.g., epiphyses, small bones). It also tends to occur in younger individuals than conventional chondrosarcoma. It does not typically metastasize to regional lymph nodes or the liver more commonly than other sites. While local recurrence is high, its metastatic potential is low compared to higher-grade conventional types.

Question 5251

Topic: 10. Pathology and Oncology

Which of the following describes a 'skip lesion' in chondrosarcoma?

. A metastatic lesion in a distant organ, such as the lung.
. A second, distinct tumor focus within the same bone, discontinuous from the primary tumor.
. A lesion involving adjacent soft tissues only, without bone involvement.
. A benign cartilaginous lesion mimicking chondrosarcoma.
. A recurrence at the surgical incision site.

Correct Answer & Explanation

. A second, distinct tumor focus within the same bone, discontinuous from the primary tumor.

Explanation

A 'skip lesion' refers to a second, distinct tumor focus within the same bone or even in a different bone, discontinuous from the primary tumor. These must be identified preoperatively or intraoperatively as they require wider resection to prevent local recurrence. Distant metastases are simply metastases. Local soft tissue involvement is direct extension. Benign mimics are differential diagnoses. Recurrence at the incision is a local recurrence.

Question 5252

Topic: 10. Pathology and Oncology

What immunohistochemical marker is commonly used to support a diagnosis of chondrosarcoma, particularly in distinguishing it from other spindle cell lesions?

. S100 protein
. CD31
. Desmin
. Pan-cytokeratin
. CD34

Correct Answer & Explanation

. S100 protein

Explanation

S100 protein is a highly sensitive and relatively specific immunohistochemical marker for cartilaginous differentiation, making it very useful in supporting the diagnosis of chondrosarcoma and distinguishing it from other spindle cell or undifferentiated sarcomas. CD31 and CD34 are endothelial markers. Desmin indicates muscle differentiation. Pan-cytokeratin indicates epithelial differentiation.

Question 5253

Topic: 10. Pathology and Oncology

A 65-year-old male with a solitary osteochondroma of the scapula presents with increasing pain and a palpable mass. Imaging shows a 3 cm thick cartilaginous cap. Biopsy confirms secondary peripheral chondrosarcoma. What is the appropriate surgical margin for this lesion?

. Intralesional
. Marginal
. Wide (at least 1 cm of normal tissue)
. Palliative debulking
. Frozen section control only

Correct Answer & Explanation

. Wide (at least 1 cm of normal tissue)

Explanation

For a secondary peripheral chondrosarcoma, especially of this size and location, a wide surgical margin (typically at least 1-2 cm of normal tissue in all directions) is critical to achieve local control and prevent recurrence. Intralesional and marginal resections are associated with high recurrence rates for chondrosarcoma. Palliative debulking is not appropriate for a resectable lesion. Frozen section control can be useful for margin assessment but does not define the surgical principle.

Question 5254

Topic: Bone Tumors

Which of the following is most commonly associated with the highest rate of local recurrence after intralesional treatment?

. Grade 1 conventional chondrosarcoma of the phalanx
. Grade 2 conventional chondrosarcoma of the proximal humerus
. Clear cell chondrosarcoma of the proximal tibia
. Mesenchymal chondrosarcoma of the sacrum
. Grade 3 conventional chondrosarcoma of the ilium

Correct Answer & Explanation

. Grade 3 conventional chondrosarcoma of the ilium

Explanation

Intralesional treatment is generally contraindicated for any chondrosarcoma due to high recurrence rates, but its application to Grade 3 conventional chondrosarcoma of the ilium would yield the highest local recurrence rate due to the tumor's aggressive nature, high-grade histology, and the inherent difficulty of achieving true intralesional margins in the pelvis without contamination. Even Grade 2 lesions treated intralesionally would have high recurrence, but Grade 3 is worse. Phalanx lesions are often low-grade and more amenable to marginal excision. Mesenchymal chondrosarcoma and clear cell chondrosarcoma are distinct entities with their own characteristics.

Question 5255

Topic: 10. Pathology and Oncology

A patient undergoing evaluation for a possible chondrosarcoma has a Tc-99m MDP bone scan showing increased uptake in the lesion. What does this finding indicate?

. Definitive evidence of malignancy
. Increased metabolic activity, suggestive of a tumor or inflammatory process
. Presence of a benign enchondroma only
. Sclerosis within the lesion
. Absence of metastatic disease

Correct Answer & Explanation

. Increased metabolic activity, suggestive of a tumor or inflammatory process

Explanation

Increased uptake on a Tc-99m MDP bone scan indicates increased osteoblastic activity or blood flow, which can be seen in various conditions including tumors (both benign and malignant), fractures, infections, and inflammatory processes. It is not definitive evidence of malignancy, nor does it exclude benign enchondroma, as some benign lesions can also show uptake. It primarily suggests increased metabolic activity within the bone at the site of the lesion. It cannot comment on the absence of metastatic disease elsewhere without further imaging.

Question 5256

Topic: 10. Pathology and Oncology

What is the primary site of metastasis for conventional chondrosarcoma?

. Regional lymph nodes
. Liver
. Brain
. Lungs
. Bone marrow

Correct Answer & Explanation

. Lungs

Explanation

The primary site of metastasis for conventional chondrosarcoma, like most sarcomas, is the lungs. Metastasis to regional lymph nodes is rare, and while other sites can be involved, the lungs are by far the most common target for hematogenous dissemination.

Question 5257

Topic: Bone Tumors

Which of the following features on a plain radiograph is most concerning for a low-grade central chondrosarcoma over an enchondroma?

. Expansile remodeling of the bone
. Presence of an intact sclerotic rim
. Punctate or ring-and-arc calcifications
. Diffuse cortical thickening and endosteal scalloping >2/3 of cortical thickness
. Well-defined lucent lesion in the diaphysis

Correct Answer & Explanation

. Diffuse cortical thickening and endosteal scalloping >2/3 of cortical thickness

Explanation

Diffuse cortical thickening and endosteal scalloping greater than 2/3 of the cortical thickness are strong indicators of a low-grade chondrosarcoma, signifying an infiltrative and slowly aggressive growth pattern. While expansile remodeling and calcifications can be seen in both, and an intact sclerotic rim usually favors benignity, significant cortical erosion/scalloping points towards malignancy. A well-defined lucent lesion is non-specific.

Question 5258

Topic: 10. Pathology and Oncology

A 50-year-old patient with a history of Grade 1 chondrosarcoma of the rib, treated with wide resection, presents with a new, rapidly growing mass at the previous surgical site. Biopsy reveals a high-grade pleomorphic sarcoma. What is the most likely diagnosis?

. Recurrent Grade 1 chondrosarcoma
. Post-radiation sarcoma
. Dedifferentiated chondrosarcoma
. Metastatic sarcoma from another primary site
. A new primary osteosarcoma

Correct Answer & Explanation

. Dedifferentiated chondrosarcoma

Explanation

The scenario describes a recurrence of a previously resected low-grade chondrosarcoma, but this time with a high-grade, pleomorphic sarcomatous component. This abrupt change in histology from a low-grade chondrosarcoma to a high-grade non-cartilaginous sarcoma is the hallmark of dedifferentiated chondrosarcoma. Post-radiation sarcoma would require a history of radiation to the area, which is not mentioned. A new primary osteosarcoma or metastatic sarcoma from another site is less likely than dedifferentiation given the history of chondrosarcoma at the same site. Recurrent Grade 1 would not show high-grade pleomorphic features.

Question 5259

Topic: Bone Tumors

What is the most common subtype of chondrosarcoma?

. Mesenchymal chondrosarcoma
. Clear cell chondrosarcoma
. Dedifferentiated chondrosarcoma
. Conventional central chondrosarcoma
. Juxtacortical chondrosarcoma

Correct Answer & Explanation

. Conventional central chondrosarcoma

Explanation

Conventional central chondrosarcoma accounts for the vast majority (approximately 85-90%) of all chondrosarcomas. The other subtypes listed are rare variants.

Question 5260

Topic: 10. Pathology and Oncology

Which factor makes the diagnosis of low-grade chondrosarcoma challenging histologically?

. Lack of S100 expression
. Abundant mitotic figures
. High cellularity and significant nuclear pleomorphism
. Close resemblance to benign enchondroma
. Presence of osteoid formation

Correct Answer & Explanation

. Close resemblance to benign enchondroma

Explanation

The histological differentiation between a benign enchondroma and a low-grade (Grade 1) conventional chondrosarcoma is notoriously challenging. Both can have similar features, and grading often relies on subtle differences in cellularity, nuclear atypia, and the presence of myxoid change. High cellularity, significant pleomorphism, and abundant mitoses are features of higher-grade tumors. Lack of S100 would argue against chondroid differentiation. Osteoid formation points away from pure chondrosarcoma.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page