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10. Pathology and Oncology MCQs

Practice Set 43 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 841

Topic: 10. Pathology and Oncology

A 30-year-old male presents with a painful mass in the distal radius. Radiographs show a lytic, eccentric lesion in the epiphysis. MRI confirms the lesion, which appears locally aggressive. A core needle biopsy is performed. Histology reveals multinucleated giant cells and mononuclear stromal cells. What is the MOST appropriate next step given these findings?

. Proceed directly to surgical excision, as this is pathognomonic for Giant Cell Tumor.
. Repeat the biopsy with a larger needle to ensure adequate sampling.
. Correlate the biopsy findings with clinical presentation and imaging; if discordant, consider repeat biopsy or open biopsy.
. Initiate chemotherapy immediately due to the aggressive nature.
. Prescribe analgesics and observe for 6 months.

Correct Answer & Explanation

. Correlate the biopsy findings with clinical presentation and imaging; if discordant, consider repeat biopsy or open biopsy.

Explanation

Correct Answer: CThe description (multinucleated giant cells and mononuclear stromal cells in an epiphyseal lytic lesion) is highly suggestive of Giant Cell Tumor of Bone (GCT). However, it's crucial to correlate biopsy findings with clinical presentation and imaging. While suggestive, this appearance can rarely be seen in other lesions (e.g., brown tumor of hyperparathyroidism, aneurysmal bone cyst, even chondroblastoma). If the clinical and imaging picture strongly supports GCT, this biopsy result is generally sufficient. If there's any discordance, or if there's concern about sampling error missing a higher-grade component, repeat biopsy or open biopsy may be considered to confirm. Directly proceeding to surgery is often appropriate if the diagnosis is clear. Immediate chemotherapy is incorrect as GCT is typically treated surgically. Observation is inappropriate for an aggressive lesion.

Question 842

Topic: 10. Pathology and Oncology

A biopsy report for a suspected bone tumor returns as 'benign reactive bone'. However, the clinical and radiological picture remains highly suspicious for malignancy. What is the MOST appropriate next action?

. Reassure the patient and discharge, relying on the biopsy result.
. Immediately initiate empiric chemotherapy.
. Refer for radiation therapy based on imaging findings.
. Repeat the biopsy, potentially with an open technique or different imaging guidance, after reviewing all clinical and imaging data.
. Prescribe pain medication and monitor with serial radiographs.

Correct Answer & Explanation

. Repeat the biopsy, potentially with an open technique or different imaging guidance, after reviewing all clinical and imaging data.

Explanation

Correct Answer: DWhen there is a significant discordance between the biopsy results and the clinical/radiological findings (often termed 'clinicopathologic discordance'), the biopsy result should not be blindly accepted. 'Benign reactive bone' could be due to sampling error (e.g., biopsying surrounding reactive bone instead of the tumor), or the lesion might be a low-grade malignancy difficult to diagnose. The most appropriate next step is to carefully review all available data (imaging, clinical history, initial biopsy pathology) and, if suspicion for malignancy remains high, repeat the biopsy, potentially using an open technique to obtain a larger, more representative sample, or re-target with different imaging guidance.

Question 843

Topic: 10. Pathology and Oncology

A 35-year-old male presents with incidental discovery of a lucent lesion with punctate calcifications in the metadiaphysis of the proximal phalanx of his hand. No pain or swelling.
Based on the provided image, what is the most likely diagnosis?

. Chondrosarcoma
. Osteochondroma
. Enchondroma
. Fibrous Dysplasia
. Giant Cell Tumor

Correct Answer & Explanation

. Enchondroma

Explanation

Correct Answer: CEnchondromas are the most common benign cartilaginous tumors of the small bones of the hands and feet. Their classic radiographic appearance includes a lucent, intramedullary lesion with characteristic punctate or rings-and-arcs calcifications. The asymptomatic nature and typical location (proximal phalanx) strongly favor enchondroma. Chondrosarcoma is less likely given the benign radiographic features and lack of symptoms. Osteochondroma is an exostosis, not intramedullary. Fibrous dysplasia has a ground-glass matrix. Giant cell tumor is typically epiphyseal and purely lytic.

Question 844

Topic: 10. Pathology and Oncology

When differentiating a solitary enchondroma from a low-grade chondrosarcoma in a long bone, which of the following radiographic features, as potentially depicted in the image, is most concerning for malignancy?

. Endosteal scalloping > 2/3 cortical thickness
. Punctate calcifications
. Intralesional fat signal on MRI
. Well-defined sclerotic border
. Absence of periosteal reaction

Correct Answer & Explanation

. Endosteal scalloping > 2/3 cortical thickness

Explanation

Correct Answer: ASignificant endosteal scalloping, particularly when it exceeds 2/3 of the cortical thickness, is a key radiographic indicator that suggests a more aggressive lesion, such as a low-grade chondrosarcoma, rather than a benign enchondroma. This indicates active erosion of the inner cortex. Punctate calcifications are typical for both benign and malignant chondroid lesions. Intralesional fat is often seen in bone infarcts or areas of marrow, not typically a chondroid tumor. A well-defined sclerotic border and absence of periosteal reaction are features more consistent with a benign lesion.

Question 845

Topic: 10. Pathology and Oncology

A 40-year-old female has an asymptomatic enchondroma incidentally found in her proximal humerus during a shoulder MRI for rotator cuff impingement. The lesion measures 2x3cm, shows typical chondroid matrix calcifications, and no cortical breach or periosteal reaction, as seen in the representative image. What is the most appropriate initial management?

. Immediate curettage and bone grafting
. Prophylactic internal fixation
. Annual radiographic follow-up
. Biopsy
. Systemic chemotherapy

Correct Answer & Explanation

. Annual radiographic follow-up

Explanation

Correct Answer: CFor an asymptomatic, radiographically benign-appearing enchondroma in a low-stress location like the proximal humerus, observation with serial radiographic follow-up (typically annual for 2-3 years) is the standard initial management. This approach monitors for any changes that might suggest malignant transformation or complications. Surgical intervention, biopsy, or more aggressive treatments are reserved for symptomatic lesions, those with concerning radiographic features (e.g., significant growth, cortical destruction, new pain), or evidence of progression.

Question 846

Topic: 10. Pathology and Oncology
A 12-year-old boy presents with multiple enchondromas affecting the long bones of one limb and multiple cutaneous hemangiomas, as suggested by the clinical image. This presentation is most consistent with:
. Ollier's disease
. Maffucci's syndrome
. McCune-Albright syndrome
. Neurofibromatosis Type 1
. Gorlin syndrome

Correct Answer & Explanation

. Maffucci's syndrome

Explanation

Maffucci's syndrome is characterized by the presence of multiple enchondromas and cutaneous (or visceral) hemangiomas. This combination is pathognomonic for the syndrome. Ollier's disease involves multiple enchondromas but without associated hemangiomas. McCune-Albright syndrome involves fibrous dysplasia, café-au-lait spots, and endocrine dysfunction. Neurofibromatosis Type 1 features neurofibromas and café-au-lait spots. Gorlin syndrome (Basal Cell Nevus Syndrome) involves multiple basal cell carcinomas and jaw keratocysts.

Question 847

Topic: 10. Pathology and Oncology

On MRI, a benign enchondroma typically demonstrates which of the following signal characteristics, as shown in the representative T1 and T2 images?

. Low signal on T1, very high signal on T2 with internal septations
. High signal on T1, low signal on T2 with solid enhancement
. Isointense on T1 and T2
. Heterogeneous signal with a fluid-fluid level
. Perilesional edema with cortical destruction

Correct Answer & Explanation

. Low signal on T1, very high signal on T2 with internal septations

Explanation

Correct Answer: ABenign hyaline cartilage, as seen in an enchondroma, typically appears low signal on T1-weighted images and very high signal on T2-weighted images due to its high water content. It often shows a lobulated configuration with internal septations and peripheral enhancement after contrast, but typically not solid or aggressive enhancement. Fluid-fluid levels are characteristic of aneurysmal bone cysts, and perilesional edema with cortical destruction is indicative of malignancy or infection.

Question 848

Topic: 10. Pathology and Oncology
A 60-year-old male presents with dull, constant pain in his distal femur. Radiographs show a 4 cm intramedullary lesion with a lobulated contour, speckled calcifications, and mild endosteal scalloping (<1/3 cortical thickness), as shown in the X-ray. A recent MRI shows no clear cortical breach or soft tissue mass, but increased tracer uptake on bone scan compared to previous studies. What is the most appropriate next step?
. Continued observation with annual X-rays
. PET scan for metabolic activity
. Open biopsy
. Prophylactic internal fixation
. Radiation therapy

Correct Answer & Explanation

. Open biopsy

Explanation

New onset or worsening pain in a chondroid lesion, especially in a long bone of an older patient, coupled with increased tracer uptake on a bone scan (suggesting metabolic activity), are concerning signs for malignant transformation to chondrosarcoma, even if other radiographic features are subtle. While a PET scan could also assess metabolic activity, a definitive diagnosis requires a biopsy (either open or image-guided core biopsy if sufficient tissue can be obtained) to assess the histology and grade the tumor. Observation is inappropriate given the symptoms and bone scan findings. Prophylactic fixation and radiation therapy are not initial diagnostic steps.

Question 849

Topic: 10. Pathology and Oncology

An enchondroma-like lesion in which of the following locations, as exemplified by the image, carries the highest intrinsic risk of being a low-grade chondrosarcoma, even if radiographically benign-appearing?

. Phalanges of the hand
. Distal femur
. Proximal humerus
. Pelvis
. Distal tibia

Correct Answer & Explanation

. Pelvis

Explanation

Correct Answer: DChondroid lesions in the axial skeleton (pelvis, scapula, sternum, ribs) and proximal long bones (femur, humerus) carry a higher intrinsic risk of being a low-grade chondrosarcoma compared to those in the small bones of the hands and feet or more distal long bones, even when imaging features appear benign. Lesions in the pelvis, in particular, are notorious for challenging differentiation and a higher index of suspicion for malignancy is warranted due to the difficulty in assessing subtle changes and the potential for significant morbidity if mismanaged.

Question 850

Topic: 10. Pathology and Oncology

What feature, potentially seen in the image, is least suggestive of a benign enchondroma and more concerning for a low-grade chondrosarcoma?

. Smooth, intact periosteum
. Sharp interface with normal marrow
. Absence of soft tissue mass
. Extensive bone destruction and cortical breakthrough
. Lobulated growth pattern

Correct Answer & Explanation

. Extensive bone destruction and cortical breakthrough

Explanation

Correct Answer: DExtensive bone destruction and cortical breakthrough with an associated soft tissue mass are definitive signs of an aggressive, malignant process, such as a chondrosarcoma. Benign enchondromas typically have an intact, smooth periosteum, a sharp interface with normal marrow, and do not extend into the soft tissues. A lobulated growth pattern is characteristic of cartilaginous tumors, both benign and malignant, and thus is not a distinguishing feature for malignancy on its own.

Question 851

Topic: Bone Tumors

A 12-year-old boy presents with a painless, firm mass on the medial aspect of his distal femur. Plain radiographs are obtained. Which specific feature on the X-ray confirms the diagnosis of an osteochondroma and differentiates it from other surface lesions?

. A 'sunburst' periosteal reaction
. A lytic lesion with a sclerotic rim
. Continuity of the cortex and medullary bone of the lesion with the parent bone
. A purely cartilaginous mass
. Presence of internal calcifications

Correct Answer & Explanation

. Continuity of the cortex and medullary bone of the lesion with the parent bone

Explanation

Correct Answer: CThe hallmark radiographic feature of an osteochondroma is the continuity of the cortical and medullary bone of the exostosis with that of the underlying parent bone. This is crucial for differentiation. 'Sunburst' reaction suggests osteosarcoma. Lytic lesions with sclerotic rims are seen in osteoid osteoma. A purely cartilaginous mass is not typical for an osteochondroma, which is osteocartilaginous. Internal calcifications can be seen in various cartilaginous lesions.

Question 852

Topic: 10. Pathology and Oncology

A 45-year-old man, with a known osteochondroma of the proximal tibia since childhood, reports a recent increase in size and new dull aching pain over the past 6 months. Radiographs are equivocal for changes, but an MRI shows a heterogeneous cartilage cap measuring 2.8 cm. What is the most appropriate next management step?

. Observe for another 6 months.
. Prescribe NSAIDs and physiotherapy.
. Refer for percutaneous core needle biopsy.
. Perform a local curettage of the lesion.
. Recommend prophylactic amputation.

Correct Answer & Explanation

. Refer for percutaneous core needle biopsy.

Explanation

Correct Answer: CThe new pain, recent growth in an adult, and a cartilage cap thickness greater than 2 cm are highly suspicious for malignant transformation to a secondary peripheral chondrosarcoma. A percutaneous core needle biopsy is the most appropriate next step to confirm the diagnosis and determine the grade of the tumor, which will guide definitive surgical planning. Observation or conservative treatment is inappropriate given the suspicion. Prophylactic amputation is never indicated without confirmed malignancy and extensive disease.

Question 853

Topic: 10. Pathology and Oncology

A 7-year-old child presents with multiple bony masses and a family history of similar lesions. Genetic testing is considered. Which of the following genetic mutations is most commonly associated with Hereditary Multiple Exostoses (HME)?

. TP53
. EXT1 or EXT2
. COL1A1
. IDH1 or IDH2
. SMAD3

Correct Answer & Explanation

. EXT1 or EXT2

Explanation

Correct Answer: BHereditary Multiple Exostoses (HME), also known as Multiple Osteochondromas, is an autosomal dominant disorder caused by germline mutations in either the EXT1 or EXT2 genes. These genes encode glycosyltransferases involved in heparan sulfate synthesis, a critical component of the extracellular matrix. TP53 is associated with sarcomas (e.g., Li-Fraumeni). COL1A1 is linked to osteogenesis imperfecta. IDH1/IDH2 mutations are seen in some chondrosarcomas (including dedifferentiated). SMAD3 is not directly linked to HME.

Question 854

Topic: 10. Pathology and Oncology

A 30-year-old patient with a known osteochondroma is being evaluated for new onset pain and potential malignant transformation. Which imaging modality is most effective for evaluating the cartilage cap thickness of an osteochondroma, especially when assessing for malignant transformation?

. Plain Radiographs
. Computed Tomography (CT)
. Magnetic Resonance Imaging (MRI)
. Bone Scintigraphy
. Ultrasound

Correct Answer & Explanation

. Magnetic Resonance Imaging (MRI)

Explanation

Correct Answer: CMagnetic Resonance Imaging (MRI) is the gold standard for evaluating the cartilage cap thickness of an osteochondroma. The cartilage cap appears as a high signal intensity on T2-weighted images. A cap thickness greater than 2 cm in an adult is a strong indicator of malignant transformation to a secondary chondrosarcoma. Plain radiographs and CT are excellent for bony morphology but poor for cartilage visualization. Bone scintigraphy can show increased uptake but is not specific for cap thickness. Ultrasound can sometimes visualize the cap but is less reliable and quantitative than MRI.

Question 855

Topic: 10. Pathology and Oncology

A 16-year-old active athlete presents with a painful, enlarging mass over a known osteochondroma on the posterior aspect of his distal femur. Examination reveals a fluctuant, tender swelling. What is the most likely complication?

. Malignant transformation
. Fracture through the stalk
. Pseudoaneurysm formation
. Symptomatic bursitis
. Nerve compression

Correct Answer & Explanation

. Symptomatic bursitis

Explanation

Correct Answer: DThe development of a painful, enlarging, fluctuant mass over an osteochondroma, particularly in an area subject to friction or repetitive motion, is highly suggestive of symptomatic bursa formation. The bursa develops in response to irritation from the osteochondroma. While other complications are possible, the description best fits bursitis. Malignant transformation typically presents with a hard, rapidly enlarging mass and increased pain, but less often fluctuant. Fracture causes acute, sharp pain. Pseudoaneurysm would have pulsatile swelling. Nerve compression causes neurological symptoms.

Question 856

Topic: 10. Pathology and Oncology

Which of the following statements regarding the malignant transformation of a solitary osteochondroma is FALSE?

. The risk of malignant transformation is higher in Hereditary Multiple Exostoses (HME) than in solitary osteochondromas.
. Malignant transformation most commonly results in a secondary peripheral chondrosarcoma.
. Increased pain, rapid growth, and a cartilage cap thickness > 2 cm in an adult are warning signs.
. The risk of malignant transformation for a solitary osteochondroma is generally less than 1%.
. Malignant transformation typically occurs in children under the age of 10.

Correct Answer & Explanation

. Malignant transformation typically occurs in children under the age of 10.

Explanation

Correct Answer: EMalignant transformation of osteochondromas typically occurs in adults, usually after skeletal maturity, not in children under 10. The average age for secondary chondrosarcoma is 30-40 years. The other statements are true: HME carries a higher risk (5-25%) than solitary lesions (<1%), it transforms into peripheral chondrosarcoma, and the described signs are indeed warning signs.

Question 857

Topic: 10. Pathology and Oncology

A 6-year-old boy is diagnosed with an osteochondroma of the distal femur. His parents are concerned about its future growth. Which of the following describes the typical growth pattern of an osteochondroma?

. Rapidly invasive growth throughout life
. Slow growth, typically stopping at skeletal maturity
. Growth that accelerates after skeletal maturity
. Growth independent of the adjacent growth plate
. Cycles of growth and regression throughout childhood

Correct Answer & Explanation

. Slow growth, typically stopping at skeletal maturity

Explanation

Correct Answer: BOsteochondromas typically grow slowly during childhood, mimicking the growth of the adjacent growth plate. Their growth usually ceases with the closure of the adjacent physis at skeletal maturity. Any growth or enlargement after skeletal maturity, particularly if accompanied by pain, raises suspicion for malignant transformation. Rapid invasive growth or cycles of regression are not typical.

Question 858

Topic: 10. Pathology and Oncology

A 40-year-old patient with a history of Hereditary Multiple Exostoses (HME) presents with a new, rapidly enlarging, painful mass in the pelvic region. Given the patient's history, what is the approximate risk of malignant transformation for a patient with HME?

. Less than 1%
. 1-2%
. 5-25%
. 50%
. Nearly 100%

Correct Answer & Explanation

. 5-25%

Explanation

Correct Answer: CThe risk of malignant transformation in patients with Hereditary Multiple Exostoses (HME) is significantly higher than in solitary osteochondromas. Estimates range from 5% to 25%, depending on the study and diagnostic criteria. Solitary lesions have a risk of less than 1%. The clinical scenario strongly suggests malignant transformation, reinforcing the importance of knowing the increased risk in HME.

Question 859

Topic: Bone Tumors

A 13-year-old female presents with a painful osteochondroma of the distal femur that impinges on the vastus medialis muscle during knee flexion, causing significant functional limitation. Which of the following is the most appropriate treatment?

. Physical therapy to improve flexibility
. NSAIDs and activity modification
. Surgical excision of the osteochondroma
. Steroid injection into the lesion
. Observation until skeletal maturity

Correct Answer & Explanation

. Surgical excision of the osteochondroma

Explanation

Correct Answer: CWhen an osteochondroma causes mechanical symptoms such as muscle impingement and pain during movement, surgical excision is the definitive treatment. Conservative measures like physical therapy, NSAIDs, or steroid injections are unlikely to resolve mechanical impingement. Observation would allow symptoms to persist or worsen. Surgical excision relieves the mechanical obstruction.

Question 860

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with a pathologic fracture of the distal femur through a mixed lytic and blastic metaphyseal lesion. Radiographs reveal aggressive periosteal reaction. What is the most appropriate initial management?

. Immediate open reduction and internal fixation to restore mechanical alignment
. Immediate intramedullary nailing to prevent further displacement
. Splinting, cross-sectional imaging, and staging followed by biopsy
. Above-knee amputation
. Excisional biopsy and frozen section analysis

Correct Answer & Explanation

. Splinting, cross-sectional imaging, and staging followed by biopsy

Explanation

Pathologic fractures through suspected primary malignant bone tumors should be immobilized pending complete staging and planned biopsy. Immediate internal fixation contaminates the entire compartment, potentially jeopardizing future limb salvage.

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