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10. Pathology and Oncology MCQs

Practice Set 256 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 5101

Topic: 10. Pathology and Oncology

A patient presents with a slowly growing, painless, soft mass adjacent to the knee joint. MRI shows a well-circumscribed fatty lesion within the joint capsule but external to the synovium. This is most consistent with:

. Lipoma arborescens
. Intra-articular lipoma
. Bursitis
. Ganglion cyst
. Meniscal cyst

Correct Answer & Explanation

. Intra-articular lipoma

Explanation

An intra-articular lipoma refers to a benign, circumscribed collection of mature adipose tissue located within the joint capsule. This differentiates it from lipoma arborescens, which is a diffuse, villous, lipomatous proliferation of the synovial membrane itself. The description specifies a 'well-circumscribed fatty lesion within the joint capsule but external to the synovium', making intra-articular lipoma the best fit.

Question 5102

Topic: 10. Pathology and Oncology

Which of the following features on MRI is LEAST indicative of a malignant fatty tumor (liposarcoma) in an extremity?

. Presence of thick septations (>2mm)
. Nodular non-adipose components
. Size greater than 10 cm
. Diffuse signal suppression on fat-suppressed sequences
. Peritumoral edema

Correct Answer & Explanation

. Diffuse signal suppression on fat-suppressed sequences

Explanation

Diffuse signal suppression on fat-suppressed sequences (e.g., STIR, fat-saturated T2) indicates that the lesion is composed primarily of fat. This is characteristic of a benign lipoma. While some well-differentiated liposarcomas are predominantly fat, the presence of non-adipose components, thick septations, nodularity, or peritumoral edema are much stronger and more specific indicators of malignancy within a fatty tumor. Therefore, uniform fat suppression is least indicative of malignancy.

Question 5103

Topic: 10. Pathology and Oncology

A 50-year-old develops a deep-seated, painful, slowly enlarging mass within the quadriceps muscle. Biopsy confirms an intramuscular lipoma. What is the recommended treatment?

. Observation and reassurance
. Physical therapy
. Steroid injection
. Marginal excision
. Wide local excision

Correct Answer & Explanation

. Marginal excision

Explanation

Intramuscular lipomas are benign but can be infiltrative and cause symptoms such as pain or functional impairment due to their location and growth within muscle. Due to their infiltrative nature, simple enucleation may be difficult or lead to incomplete removal. Therefore, marginal excision (removing the tumor with a thin cuff of macroscopically normal tissue) is the recommended treatment to alleviate symptoms and reduce the risk of local recurrence. Wide local excision is reserved for malignant tumors, and observation is not appropriate for symptomatic or enlarging lesions.

Question 5104

Topic: 10. Pathology and Oncology

True or False: A benign subcutaneous lipoma frequently undergoes malignant transformation into a liposarcoma.

. True
. False

Correct Answer & Explanation

. False

Explanation

False. Benign subcutaneous lipomas very rarely, if ever, undergo malignant transformation into liposarcoma. When a fatty mass in an adult appears to have 'transformed,' it is far more likely that the lesion was a well-differentiated liposarcoma (atypical lipomatous tumor) from the outset that was either misdiagnosed, grew over time, or recurred. Clinically, a rapidly growing or deep-seated fatty mass should always prompt suspicion for malignancy rather than benign transformation.

Question 5105

Topic: Soft Tissue Tumors & Metastasis

Which liposarcoma subtype is characterized by prominent pleomorphic lipoblasts, bizarre giant cells, and atypical spindle cells, often without a significant myxoid component?

. Well-differentiated liposarcoma
. Dedifferentiated liposarcoma
. Myxoid liposarcoma
. Round cell liposarcoma
. Pleomorphic liposarcoma

Correct Answer & Explanation

. Pleomorphic liposarcoma

Explanation

Pleomorphic liposarcoma is a high-grade sarcoma characterized by significant cellular pleomorphism, with highly atypical, bizarre giant cells and pleomorphic lipoblasts. It often lacks the prominent myxoid stroma of myxoid liposarcoma or the low-grade fatty components of well-differentiated liposarcoma. Distinguishing it from other undifferentiated pleomorphic sarcomas often relies on the definitive identification of pleomorphic lipoblasts.

Question 5106

Topic: 10. Pathology and Oncology

An 8 cm fatty tumor in the retroperitoneum is diagnosed as an Atypical Lipomatous Tumor (ALT) via core biopsy. What is the most appropriate management, considering its location?

. Observation with yearly MRI
. Marginal excision
. Wide local excision with negative margins, possibly with neoadjuvant or adjuvant radiotherapy
. Chemotherapy followed by excision
. Referral for cryoablation

Correct Answer & Explanation

. Wide local excision with negative margins, possibly with neoadjuvant or adjuvant radiotherapy

Explanation

In retroperitoneal, mediastinal, and spermatic cord locations, Atypical Lipomatous Tumor (ALT) is synonymous with well-differentiated liposarcoma (WDLPS) and has a significant risk of local recurrence and dedifferentiation into a higher-grade sarcoma, which then carries metastatic potential. Therefore, aggressive wide local excision with negative margins is crucial. Due to the anatomical constraints and high local recurrence rates, adjuvant radiotherapy is often considered for retroperitoneal WDLPS/DDLPS, even after seemingly complete resection.

Question 5107

Topic: 10. Pathology and Oncology

Which histological subtype of liposarcoma is most prone to distant metastasis, especially to unusual sites like bone and brain?

. Well-differentiated liposarcoma
. Atypical lipomatous tumor
. Dedifferentiated liposarcoma
. Myxoid liposarcoma (high-grade round cell variant)
. Pleomorphic liposarcoma

Correct Answer & Explanation

. Myxoid liposarcoma (high-grade round cell variant)

Explanation

Myxoid liposarcoma, particularly its high-grade variant (often referred to as 'round cell' or myxoid liposarcoma with a high round cell component), has a distinctive pattern of metastasis that includes extracompartmental sites such as the lungs, bone, and brain. This propensity for bone and brain metastasis is a key feature distinguishing it from other high-grade sarcomas that primarily metastasize to the lungs.

Question 5108

Topic: Soft Tissue Tumors & Metastasis

A 40-year-old woman presents with a soft, mobile, painless, subcutaneous mass on her forearm that has been present for several years and has not changed significantly in size. This description is most consistent with:

. Liposarcoma
. Ganglion cyst
. Epidermoid cyst
. Benign lipoma
. Neurofibroma

Correct Answer & Explanation

. Benign lipoma

Explanation

This clinical presentation is classic for a benign subcutaneous lipoma: a soft, mobile, painless, superficial mass that has been stable or slowly growing over a long period. Liposarcomas are more commonly deep, firm, and progressively enlarging. Ganglion and epidermoid cysts have different textures and etiologies. Neurofibromas can be soft but often have specific associated nerve symptoms or 'bag of worms' consistency.

Question 5109

Topic: 10. Pathology and Oncology

On post-contrast MRI, which finding in a primarily fatty soft tissue mass is most concerning for malignancy?

. Diffuse, homogeneous enhancement of the entire lesion
. No enhancement within the fatty components
. Enhancement of only thin, smooth septa (<2mm)
. Nodular or thick (>2mm) enhancing non-adipose components
. Peripheral rim enhancement

Correct Answer & Explanation

. Nodular or thick (>2mm) enhancing non-adipose components

Explanation

The presence of nodular or thick (>2mm) enhancing non-adipose components within a fatty tumor is the most concerning feature for malignancy, strongly suggesting a dedifferentiated component within a liposarcoma, or the non-lipogenic components of a myxoid liposarcoma. While thin, non-enhancing septa can be seen in benign lipomas, any enhancement of septa or nodularity should raise suspicion for ALT/WDLPS or higher-grade liposarcoma.

Question 5110

Topic: 10. Pathology and Oncology

For a classic, superficial, mobile, painless, and stable subcutaneous mass highly suggestive of a benign lipoma on clinical exam, what is the generally accepted recommendation regarding biopsy prior to excision?

. Always perform core needle biopsy
. Always perform FNA
. Biopsy is not routinely required if excision is planned for symptomatic or cosmetic reasons
. Perform excisional biopsy
. Perform open incisional biopsy

Correct Answer & Explanation

. Biopsy is not routinely required if excision is planned for symptomatic or cosmetic reasons

Explanation

For classic subcutaneous lipomas that are clinically unambiguous (soft, mobile, painless, superficial, stable over time), and if removal is requested for cosmetic reasons or mild symptoms, a pre-operative biopsy is not routinely required. The surgeon can usually confirm the benign nature at the time of excision. However, any atypical features (deep location, rapid growth, firmness, pain, large size, or suspicious imaging) mandate a pre-operative core needle biopsy.

Question 5111

Topic: 10. Pathology and Oncology

A histopathological report describes a fatty tumor composed of mature adipocytes with abundant capillaries and admixed spindle cells, often arranged in parallel arrays. What benign lipoma variant is being described?

. Fibrolipoma
. Angiolipoma
. Spindle cell lipoma
. Pleomorphic lipoma
. Chondroid lipoma

Correct Answer & Explanation

. Spindle cell lipoma

Explanation

Spindle cell lipoma is a benign lipomatous tumor characterized by a proliferation of mature adipocytes intermixed with uniform, slender spindle cells that are often arranged in fascicles, within a myxoid to collagenous matrix. It is typically found in the posterior neck, shoulder, and back of older men. Angiolipomas are painful and vascular. Fibrolipomas have a prominent fibrous component. Pleomorphic lipomas contain characteristic floret-type giant cells.

Question 5112

Topic: 10. Pathology and Oncology

The most significant predictor of local recurrence in resected liposarcoma is:

. Patient age
. Tumor size
. Histological subtype
. Margin status of excision
. Adjuvant chemotherapy regimen

Correct Answer & Explanation

. Margin status of excision

Explanation

Margin status is consistently the most critical factor influencing local recurrence rates for all types of soft tissue sarcomas, including liposarcomas. Achieving negative surgical margins (R0 resection) is paramount for local disease control. While tumor size and histological subtype (especially higher grade) impact overall prognosis and risk of recurrence, the adequacy of surgical excision is the primary determinant of local control.

Question 5113

Topic: Soft Tissue Tumors & Metastasis

Which subtype of liposarcoma is generally considered most radiosensitive?

. Well-differentiated liposarcoma
. Dedifferentiated liposarcoma
. Myxoid liposarcoma
. Pleomorphic liposarcoma
. Spindle cell lipoma

Correct Answer & Explanation

. Myxoid liposarcoma

Explanation

Myxoid liposarcoma is recognized as being particularly radiosensitive compared to other sarcoma subtypes. This characteristic makes radiotherapy a crucial component of its management, often utilized in neoadjuvant (pre-operative) or adjuvant (post-operative) settings to improve local control and facilitate limb salvage.

Question 5114

Topic: 10. Pathology and Oncology

A deep, large fatty mass in the posterior thigh of a 70-year-old male is confirmed to be a well-differentiated liposarcoma (atypical lipomatous tumor). Which of the following benign entities is most likely to be confused with this lesion on imaging, necessitating careful evaluation or biopsy?

. Intramuscular hemangioma
. Benign lipoma
. Ganglion cyst
. Myxoma
. Neurofibroma

Correct Answer & Explanation

. Benign lipoma

Explanation

Well-differentiated liposarcoma (WDLPS) and atypical lipomatous tumor (ALT) are composed primarily of mature fat and, especially when well-circumscribed, can closely mimic benign lipomas on imaging. The distinction often requires careful scrutiny of subtle imaging features (septal thickening, nodularity, non-fatty components) and ultimately a biopsy with histological and sometimes molecular analysis. Other listed entities have distinct imaging characteristics.

Question 5115

Topic: 10. Pathology and Oncology

For soft tissue sarcoma surgery, what defines a "wide" margin?

. Resection with a 1 cm cuff of normal tissue
. Resection directly on the pseudocapsule
. Resection through the pseudocapsule but within the tumor
. Resection with at least 2 cm of normal tissue in all directions
. Resection within normal tissue in all directions, often requiring removal of adjacent muscle or bone

Correct Answer & Explanation

. Resection within normal tissue in all directions, often requiring removal of adjacent muscle or bone

Explanation

A 'wide' margin in soft tissue sarcoma surgery implies resection of the tumor with a substantial cuff of healthy, uninvolved tissue in all directions, often extending into an adjacent normal anatomical compartment (e.g., resecting surrounding muscle, periosteum) to achieve oncologically clear margins. While a 2 cm margin is often cited as a target, the principle is more about achieving an R0 resection within unaffected tissue rather than a strict measurement, as the required margin varies based on tumor type, grade, location, and surrounding anatomy.

Question 5116

Topic: 10. Pathology and Oncology

What is the approximate relative incidence of liposarcoma among all adult soft tissue sarcomas?

. Less than 5%
. 5-10%
. 10-15%
. 15-20%
. Greater than 20%

Correct Answer & Explanation

. 15-20%

Explanation

Liposarcoma is one of the most common subtypes of soft tissue sarcoma in adults, accounting for approximately 15-20% (and some sources state up to 24%) of all adult soft tissue sarcomas. This makes it a significant entity in orthopedic oncology.

Question 5117

Topic: 10. Pathology and Oncology

On MRI, a retroperitoneal mass shows a large fatty component with areas identical to subcutaneous fat. Adjacent to this, there is a distinct, large, non-lipomatous, solid enhancing nodule. This combination of findings is highly suggestive of:

. Benign lipoma with reactive changes
. Myxoid liposarcoma
. Dedifferentiated liposarcoma
. Pleomorphic liposarcoma
. Angiolipoma

Correct Answer & Explanation

. Dedifferentiated liposarcoma

Explanation

The characteristic imaging finding of a dedifferentiated liposarcoma (DDLPS) is the presence of a well-differentiated liposarcoma (fatty) component juxtaposed with a distinct, often larger, non-lipomatous, solid enhancing component. This solid component represents the dedifferentiated, high-grade sarcoma. This bimodal appearance is highly specific for DDLPS.

Question 5118

Topic: 10. Pathology and Oncology

A 60-year-old presents with a 7cm, deep-seated, fatty mass in the proximal thigh. Biopsy confirms a well-differentiated liposarcoma (ALT). If adequately excised with negative margins, what is the most likely long-term outcome for this patient?

. High risk of distant metastasis and poor survival.
. Good prognosis with a low risk of local recurrence and no metastatic potential.
. High risk of local recurrence but no distant metastasis.
. Requires adjuvant chemotherapy due to metastatic risk.
. Will likely dedifferentiate into a high-grade sarcoma rapidly.

Correct Answer & Explanation

. Good prognosis with a low risk of local recurrence and no metastatic potential.

Explanation

Well-differentiated liposarcomas (ALTs) in the extremities or trunk wall, when adequately excised with wide negative margins, have an excellent prognosis. They are locally aggressive but do not metastasize unless they dedifferentiate, which is a rare event in extremity ALTs compared to retroperitoneal lesions. The primary risk is local recurrence if margins are inadequate.

Question 5119

Topic: 10. Pathology and Oncology

When considering the removal of a symptomatic benign lipoma for cosmetic reasons, what is a potential disadvantage of liposuction compared to surgical excision?

. Higher risk of infection
. Longer recovery time
. Higher likelihood of incomplete removal and recurrence
. Greater scar burden
. Not effective for large lipomas

Correct Answer & Explanation

. Higher likelihood of incomplete removal and recurrence

Explanation

While liposuction can be utilized for cosmetic removal of smaller, superficial lipomas, a significant disadvantage compared to conventional surgical excision is the higher likelihood of incomplete removal, which predisposes to local recurrence. Surgical excision allows for complete enucleation of the encapsulated lipoma, ensuring lower recurrence rates.

Question 5120

Topic: 10. Pathology and Oncology

Lipomas, along with epidermal cysts, osteomas, and desmoid tumors, are associated with which genetic syndrome?

. Neurofibromatosis Type 1
. Li-Fraumeni Syndrome
. Gardner Syndrome
. Multiple Endocrine Neoplasia Type 2A
. Von Hippel-Lindau Disease

Correct Answer & Explanation

. Gardner Syndrome

Explanation

Gardner syndrome is an autosomal dominant disorder, a variant of Familial Adenomatous Polyposis (FAP), characterized by intestinal polyps that have a high risk of malignant transformation to colorectal cancer. Extracolonic manifestations include multiple osteomas, epidermoid cysts, desmoid tumors, and various soft tissue tumors, including lipomas and fibromas.

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