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10. Pathology and Oncology MCQs

Practice Set 179 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 3561

Topic: 10. Pathology and Oncology

You are treating a 45-year-old patient diagnosed with myxoid liposarcoma of the proximal thigh. In addition to local imaging and a chest CT, what additional imaging modality is uniquely indicated for staging this specific sarcoma subtype?

. Bone scintigraphy (Bone scan)
. PET/CT scan
. Whole spine MRI
. Abdominal ultrasound
. Brain MRI

Correct Answer & Explanation

. Whole spine MRI

Explanation

Myxoid liposarcoma has a unique propensity to metastasize to extrapulmonary sites, particularly the spine and bone, even before lung metastases appear. Whole spine MRI is recommended as part of the initial staging workup for this subtype.

Question 3562

Topic: 10. Pathology and Oncology

Histological examination of a well-differentiated liposarcoma (atypical lipomatous tumor) reveals hyperchromatic, atypical stromal cells within mature adipose tissue. By what primary mechanism does the characteristic gene amplification in this tumor promote oncogenesis?

. Inhibition of the p53 tumor suppressor pathway
. Activation of the Wnt/beta-catenin pathway
. Constitutive activation of tyrosine kinases
. Inhibition of apoptosis via BCL-2 overexpression
. Creation of a fusion transcription factor

Correct Answer & Explanation

. Inhibition of the p53 tumor suppressor pathway

Explanation

Well-differentiated liposarcomas feature MDM2 amplification. The MDM2 protein binds to and ubiquitinates p53, leading to its degradation and functionally inhibiting the p53 tumor suppressor pathway, promoting unchecked cell proliferation.

Question 3563

Topic: 10. Pathology and Oncology

A 55-year-old man presents with a deep intramuscular mass in his vastus lateralis. MRI demonstrates a predominantly lipomatous mass with several thick, nodular septations measuring 4 mm in width that show enhancement. What is the most appropriate management strategy?

. Marginal excision without prior biopsy
. Core needle biopsy to rule out atypical lipomatous tumor/well-differentiated liposarcoma
. Observation and repeat MRI in 12 months
. Immediate intralesional curettage
. Neoadjuvant radiation therapy followed by amputation

Correct Answer & Explanation

. Core needle biopsy to rule out atypical lipomatous tumor/well-differentiated liposarcoma

Explanation

Thick (>2 mm), nodular, and enhancing septations in a lipomatous mass on MRI are highly suspicious for an atypical lipomatous tumor (ALT) / well-differentiated liposarcoma. A core needle biopsy is required to confirm the diagnosis prior to definitive wide surgical resection.

Question 3564

Topic: Bone Tumors

A 15-year-old male undergoes intralesional curettage of a pathologically confirmed chondroblastoma of the proximal tibial epiphysis.

During the procedure, a secondary cystic, hemorrhagic, and multiloculated cavity is encountered adjacent to the primary tumor. What is the most likely diagnosis of this secondary lesion?

. Unicameral bone cyst
. Osteosarcoma
. Aneurysmal bone cyst
. Giant cell tumor of bone
. Enchondroma

Correct Answer & Explanation

. Aneurysmal bone cyst

Explanation

Secondary aneurysmal bone cysts (ABCs) occur in up to 15-20% of chondroblastomas. They present as blood-filled, multiloculated cavities that often require concurrent aggressive curettage to prevent recurrence.

Question 3565

Topic: 10. Pathology and Oncology

Myxoid liposarcoma has a distinct clinical response to neoadjuvant therapy compared to most other high-grade soft tissue sarcomas. Which of the following best describes this characteristic response?

. Extreme resistance to radiation therapy, necessitating amputation
. High sensitivity to radiation therapy, often resulting in significant tumor shrinkage
. Complete pathological response to targeted MDM2 inhibitors
. Rapid progression when treated with anthracycline-based chemotherapy
. Spontaneous regression upon cessation of weight-bearing

Correct Answer & Explanation

. High sensitivity to radiation therapy, often resulting in significant tumor shrinkage

Explanation

Myxoid liposarcoma is uniquely radiosensitive among soft tissue sarcomas. Preoperative radiation therapy often leads to dramatic tumor shrinkage, improved surgical margins, and extensive hyalinization/necrosis on the final pathology specimen.

Question 3566

Topic: 10. Pathology and Oncology

A 16-year-old male athlete presents with chronic ankle pain. Radiographs show a lytic, geographically distinct lesion within the calcaneal apophysis.

Histology demonstrates mononuclear cells with longitudinal nuclear grooves ('coffee bean' nuclei). Which highly specific epigenetic mutation is most strongly associated with this neoplasm?

. IDH1 R132C
. H3F3A G34W
. H3F3B K36M
. GNAS R201C
. EXT1 truncation

Correct Answer & Explanation

. H3F3B K36M

Explanation

Chondroblastoma is driven by a highly specific histone H3 mutation: H3F3B K36M, which is present in over 90% of cases. The other options refer to different tumors (IDH1 in enchondroma/chondrosarcoma, G34W in giant cell tumor, GNAS in fibrous dysplasia).

Question 3567

Topic: 10. Pathology and Oncology

A 65-year-old woman presents with a rapidly enlarging, painless mass in her posterior thigh. Core needle biopsy demonstrates a high-grade sarcoma with pleomorphic lipoblasts, severe nuclear atypia, and a complex karyotype lacking any specific gene fusions or MDM2 amplification. What is the most likely diagnosis?

. Well-differentiated liposarcoma
. Myxoid liposarcoma
. Dedifferentiated liposarcoma
. Pleomorphic liposarcoma
. Lipoma with fat necrosis

Correct Answer & Explanation

. Pleomorphic liposarcoma

Explanation

Pleomorphic liposarcoma is the rarest and most aggressive subtype. Unlike other subtypes, it lacks specific translocations (like t(12;16) in myxoid) or amplifications (MDM2 in well-differentiated/dedifferentiated) and is characterized by a complex karyotype and high metastatic potential.

Question 3568

Topic: 10. Pathology and Oncology

Which anatomical location carries the highest risk for an atypical lipomatous tumor (ALT) to undergo transformation into a dedifferentiated liposarcoma?

. Subcutaneous tissue of the back
. Deep intramuscular compartment of the thigh
. Retroperitoneum
. Superficial fascia of the upper extremity
. Dermis of the abdominal wall

Correct Answer & Explanation

. Retroperitoneum

Explanation

Atypical lipomatous tumors (ALTs) and well-differentiated liposarcomas (WDLPS) are morphologically identical. The retroperitoneum carries the highest risk (up to 20%) of dedifferentiation due to the difficulty in achieving complete surgical margins and longer times to symptomatic presentation.

Question 3569

Topic: Soft Tissue Tumors & Metastasis

Which of the following chromosomal translocations is highly characteristic of myxoid liposarcoma?

. t(11;22) EWSR1-FLI1
. t(X;18) SYT-SSX
. t(12;16) FUS-DDIT3
. t(2;13) PAX3-FOXO1
. t(9;22) BCR-ABL

Correct Answer & Explanation

. t(12;16) FUS-DDIT3

Explanation

Myxoid liposarcoma is characterized by the t(12;16)(q13;p11) translocation, resulting in the FUS-DDIT3 fusion gene in over 90% of cases. A variant t(2;12) EWSR1-DDIT3 translocation is seen in the remaining cases.

Question 3570

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with right knee pain. Radiographs reveal a well-defined lytic lesion in the proximal tibial epiphysis with a thin sclerotic margin. Biopsy demonstrates mononuclear cells, scattered multinucleated giant cells, and areas of pericellular calcification. What is the most appropriate initial management?

. Wide en bloc resection
. Intralesional curettage and bone grafting
. Neoadjuvant chemotherapy followed by limb salvage
. Primary radiation therapy
. Observation with serial radiographs

Correct Answer & Explanation

. Intralesional curettage and bone grafting

Explanation

The clinical and histological presentation is classic for a chondroblastoma. The standard of care is aggressive intralesional curettage, burring, and bone grafting, which offers high cure rates while preserving the joint.

Question 3571

Topic: 10. Pathology and Oncology

A deep-seated, 8 cm thigh mass in a 60-year-old man is biopsied, revealing an atypical lipomatous tumor (well-differentiated liposarcoma). Which of the following molecular markers is most consistently amplified in this pathology?

. HER2
. MDM2
. c-MYC
. BRAF
. APC

Correct Answer & Explanation

. MDM2

Explanation

Well-differentiated liposarcomas (atypical lipomatous tumors) and dedifferentiated liposarcomas are characterized by ring chromosomes and giant rod chromosomes leading to the amplification of MDM2 and CDK4 on chromosome 12q13-15.

Question 3572

Topic: 10. Pathology and Oncology

What is the primary definitive treatment for a 10 cm dedifferentiated liposarcoma located deep within the posterior compartment of the thigh without evidence of systemic metastasis?

. Excisional biopsy alone
. Wide surgical resection with radiation therapy
. Systemic chemotherapy alone
. Intralesional curettage
. Marginal excision

Correct Answer & Explanation

. Wide surgical resection with radiation therapy

Explanation

Dedifferentiated liposarcoma is a high-grade soft tissue sarcoma. The standard of care for a localized, deep, high-grade soft tissue sarcoma of the extremity is wide surgical resection typically combined with (neoadjuvant or adjuvant) radiation therapy.

Question 3573

Topic: 10. Pathology and Oncology

A 17-year-old male undergoes curettage for a proximal femur chondroblastoma. Two years later, routine imaging reveals asymptomatic 1 cm bilateral pulmonary nodules. Biopsy of a nodule confirms benign-appearing chondroblastoma. What is the most appropriate management?

. Palliative care
. Systemic multi-agent chemotherapy
. Surgical resection of the pulmonary nodules
. Whole-lung irradiation
. High-dose methotrexate

Correct Answer & Explanation

. Surgical resection of the pulmonary nodules

Explanation

Chondroblastoma can occasionally produce "benign" pulmonary metastases (occurring in 1-2% of cases) that are histologically identical to the primary tumor. Surgical resection of these nodules is the treatment of choice and carries an excellent prognosis.

Question 3574

Topic: Soft Tissue Tumors & Metastasis



A 55-year-old presents with a painless, enlarging thigh mass. Histology demonstrates mature adipocytes with variation in cell size, scattered hyperchromatic stromal cells, and lipoblasts. Molecular testing is positive for CDK4 amplification. What is the most likely diagnosis?

. Lipoma
. Myxoid liposarcoma
. Pleomorphic liposarcoma
. Well-differentiated liposarcoma
. Angiolipoma

Correct Answer & Explanation

. Well-differentiated liposarcoma

Explanation

The histological description of mature fat with hyperchromatic, atypical stromal cells and lipoblasts, combined with CDK4 (and MDM2) amplification, is diagnostic of well-differentiated liposarcoma (atypical lipomatous tumor).

Question 3575

Topic: 10. Pathology and Oncology

A 16-year-old female presents with hip pain. Radiographs reveal a well-circumscribed, lytic lesion in the greater trochanter with a thin sclerotic rim. Which of the following immunohistochemical markers is characteristically positive in the mononuclear cells of this tumor?

. Cytokeratin
. Epithelial Membrane Antigen (EMA)
. S-100
. CD34
. Desmin

Correct Answer & Explanation

. S-100

Explanation

The lesion is a chondroblastoma (presenting in an apophyseal equivalent of an epiphysis). The mononuclear cells in chondroblastoma are characteristically positive for S-100 and DOG1.

Question 3576

Topic: 10. Pathology and Oncology

A 45-year-old patient presents with a large retroperitoneal mass identified as a dedifferentiated liposarcoma. Compared to well-differentiated liposarcoma, the dedifferentiated subtype is most strongly associated with which of the following?

. A higher rate of distant metastasis and local recurrence
. The presence of the t(12;16) translocation
. A benign clinical course without need for wide margins
. Favorable response to single-agent doxorubicin
. Presentation exclusively in pediatric populations

Correct Answer & Explanation

. A higher rate of distant metastasis and local recurrence

Explanation

Dedifferentiated liposarcoma represents progression to a high-grade, non-lipogenic sarcoma. It behaves far more aggressively than well-differentiated liposarcoma, with significantly higher rates of both local recurrence and distant metastasis.

Question 3577

Topic: Soft Tissue Tumors & Metastasis

Pleomorphic liposarcoma is the rarest and most aggressive subtype of liposarcoma. Unlike well-differentiated and myxoid liposarcomas, molecular analysis of a pleomorphic liposarcoma typically exhibits:

. MDM2 gene amplification
. t(12;16)(q13;p11) translocation
. Complex and unbalanced karyotypes without a specific signature translocation
. Extrachromosomal ring chromosomes
. A uniform response to targeted MDM2 inhibitors

Correct Answer & Explanation

. Complex and unbalanced karyotypes without a specific signature translocation

Explanation

Pleomorphic liposarcoma is a high-grade sarcoma characterized by complex, chaotic, and unbalanced karyotypes. It lacks the specific MDM2 amplifications seen in well-differentiated/dedifferentiated types and the FUS-DDIT3 translocations seen in the myxoid type.

Question 3578

Topic: 10. Pathology and Oncology



A 38-year-old female presents with a deep thigh mass that is confirmed by biopsy to be a myxoid liposarcoma. This specific sarcoma subtype has a unique predilection for metastasis to which of the following locations, necessitating specific staging studies?

. Lungs exclusively
. Brain and central nervous system
. Extrapulmonary sites, particularly the spine and retroperitoneum
. Liver and gastrointestinal tract
. Regional lymph nodes

Correct Answer & Explanation

. Extrapulmonary sites, particularly the spine and retroperitoneum

Explanation

Unlike most other soft tissue sarcomas which metastasize primarily to the lungs, myxoid liposarcoma has a strong predilection for extrapulmonary metastasis, particularly to other soft tissue sites, the retroperitoneum, and the axial skeleton (spine). Staging must include whole spine/pelvis MRI.

Question 3579

Topic: Soft Tissue Tumors & Metastasis

Which subtype of liposarcoma is characterized histologically by a prominent branching capillary network resembling a "chicken-wire" vascular pattern, abundant mucinous stroma, and small lipoblasts?

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

Correct Answer & Explanation

. Myxoid liposarcoma

Explanation

Myxoid liposarcoma is histologically characterized by a rich, delicate, arborizing capillary network often described as a "chicken-wire" or "crow's feet" vascular pattern, set in a myxoid (mucinous) stroma with lipoblasts.

Question 3580

Topic: 10. Pathology and Oncology

A 15-year-old male presents with chronic knee pain. Radiographs reveal an eccentric, lytic epiphyseal lesion in the proximal tibia with a sclerotic rim. Biopsy reveals mononuclear cells with clefted nuclei and a distinct "chicken-wire" pattern of calcification.

What is the most appropriate management for this lesion?

. Observation with serial radiographs
. Wide surgical resection and endoprosthetic reconstruction
. Neoadjuvant chemotherapy followed by curettage
. Extended curettage with high-speed burr and bone grafting
. Primary radiation therapy

Correct Answer & Explanation

. Extended curettage with high-speed burr and bone grafting

Explanation

This is a classic presentation of a chondroblastoma, an epiphyseal lesion found in skeletally immature patients. Histology demonstrates mononuclear cells with grooved nuclei and "chicken-wire" calcifications. The gold standard treatment is aggressive extended curettage (often with chemical/mechanical adjuvants) and bone grafting.

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