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10. Pathology and Oncology MCQs

Practice Set 180 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 3581

Topic: 10. Pathology and Oncology

A 45-year-old male presents with a deep, painless thigh mass. Histopathologic examination reveals uniform, small round cells in a myxoid stroma with a prominent, arborizing "crow's feet" capillary network. Which of the following cytogenetic abnormalities is pathognomonic for this tumor?

. t(X;18) SYT-SSX
. t(12;16) FUS-DDIT3
. t(11;22) EWS-FLI1
. MDM2 and CDK4 amplification
. t(2;13) PAX3-FOXO1

Correct Answer & Explanation

. t(12;16) FUS-DDIT3

Explanation

The diagnosis is myxoid liposarcoma, characterized by small round cells, a myxoid background, and a delicate arborizing capillary network. The defining genetic alteration is the t(12;16) translocation, which creates the FUS-DDIT3 fusion protein.

Question 3582

Topic: 10. Pathology and Oncology

A 60-year-old patient undergoes resection of a massive retroperitoneal tumor. Histology shows mature adipose tissue with scattered highly atypical, hyperchromatic stromal cells. Fluorescence in situ hybridization (FISH) confirms the diagnosis of a well-differentiated liposarcoma. Which gene amplification was detected?

. MDM2
. c-MYC
. HER2/neu
. RB1
. TP53

Correct Answer & Explanation

. MDM2

Explanation

Well-differentiated liposarcomas (and their dedifferentiated counterparts) are characterized by supernumerary ring chromosomes that result in the amplification of MDM2 and CDK4 on chromosome 12q13-15. This amplification helps differentiate it from benign lipomas.

Question 3583

Topic: 10. Pathology and Oncology

A 17-year-old male undergoes curettage of a distal femur chondroblastoma. Two years later, routine surveillance imaging reveals three small pulmonary nodules. Biopsy of a lung nodule confirms cells identical to the primary tumor. What is the expected clinical behavior of these lung lesions?

. Rapid progression causing respiratory failure within 6 months
. Resolution following high-dose systemic chemotherapy
. Spontaneous regression over several years without intervention
. Benign metastasizing implants that can be cured with surgical resection
. Transformation into high-grade chondrosarcoma

Correct Answer & Explanation

. Benign metastasizing implants that can be cured with surgical resection

Explanation

Chondroblastoma is a benign tumor but is unique in its ability to rarely produce "benign pulmonary metastases." These implants are histologically identical to the primary tumor and are typically successfully treated with complete surgical resection, yielding excellent long-term survival.

Question 3584

Topic: 10. Pathology and Oncology

A 35-year-old male is newly diagnosed with myxoid liposarcoma of the posterior thigh. When planning staging workup for this specific histologic subtype, which of the following is true regarding its metastatic pattern?

. It primarily metastasizes to regional lymph nodes.
. Metastatic spread is overwhelmingly confined to the lungs.
. It has a high propensity to metastasize to the liver, bypassing pulmonary circulation.
. It frequently metastasizes to extrapulmonary sites, such as the spine and retroperitoneum.
. It typically metastasizes exclusively via the central nervous system (CNS).

Correct Answer & Explanation

. It frequently metastasizes to extrapulmonary sites, such as the spine and retroperitoneum.

Explanation

Unlike most other high-grade soft tissue sarcomas that metastasize primarily to the lungs, myxoid liposarcoma is unique for its tendency to metastasize to extrapulmonary bone and soft tissues, particularly the spine. Staging protocols typically include an MRI of the entire spine.

Question 3585

Topic: Bone Tumors

Histological evaluation of a curettage specimen from a proximal humerus lesion reveals sheets of mononuclear cells with "coffee-bean" nuclei, interspersed osteoclast-like giant cells, and delicate pericellular calcifications.

This constellation of findings is diagnostic for:

. Chondroblastoma
. Giant cell tumor of bone
. Clear cell chondrosarcoma
. Chondromyxoid fibroma
. Aneurysmal bone cyst

Correct Answer & Explanation

. Chondroblastoma

Explanation

The histological triad of mononuclear cells with clefted ("coffee-bean") nuclei, scattered osteoclast-like giant cells, and "chicken-wire" (pericellular) calcifications is pathognomonic for chondroblastoma.

Question 3586

Topic: 10. Pathology and Oncology

A 65-year-old female presents with a massive, painless thigh mass. Core biopsy reveals an abrupt transition from a well-differentiated, lipoma-like tumor to a high-grade, non-lipogenic sarcoma.

Which of the following statements is true regarding this specific entity?

. It lacks the MDM2/CDK4 gene amplification seen in well-differentiated liposarcoma.
. It shares the same MDM2/CDK4 gene amplification as well-differentiated liposarcoma.
. It carries the t(12;16) translocation.
. It typically responds better to chemotherapy than myxoid liposarcoma.
. It is derived from a pre-existing lipoma in 90% of cases.

Correct Answer & Explanation

. It shares the same MDM2/CDK4 gene amplification as well-differentiated liposarcoma.

Explanation

This describes dedifferentiated liposarcoma, which represents high-grade progression of a well-differentiated liposarcoma. Importantly, both well-differentiated and dedifferentiated liposarcomas share the exact same genetic hallmark: amplification of the MDM2 and CDK4 genes.

Question 3587

Topic: Soft Tissue Tumors & Metastasis

Among the main histological subtypes of liposarcoma, which carries the worst overall prognosis, highest rate of metastasis, and is characterized by a complex karyotype lacking a specific, defining chromosomal translocation?

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

Correct Answer & Explanation

. Pleomorphic liposarcoma

Explanation

Pleomorphic liposarcoma is the rarest and most aggressive subtype. It presents as a high-grade pleomorphic sarcoma with complex karyotypes (lacking specific translocations or MDM2 amplifications) and has the highest rate of distant metastasis and lowest survival.

Question 3588

Topic: 10. Pathology and Oncology

When evaluating a deep soft tissue mass of the thigh on MRI, which of the following imaging characteristics is highly suggestive of a well-differentiated liposarcoma rather than a benign lipoma?

. T1 hyperintensity with thick (>2mm), nodular, enhancing septations
. Homogeneous T1 hyperintensity without any internal septations
. T1 hypointensity with homogeneous T2 hyperintensity
. A complete lack of fat signal on all sequences
. Multiple fluid-fluid levels within a cystic cavity

Correct Answer & Explanation

. T1 hyperintensity with thick (>2mm), nodular, enhancing septations

Explanation

Well-differentiated liposarcoma shares the bright T1 signal of fat seen in benign lipomas but is distinguished by the presence of thick (>2mm), nodular, and contrast-enhancing internal septations.

Question 3589

Topic: 10. Pathology and Oncology

A 14-year-old patient presents with a large joint effusion and severe shoulder pain. Radiographs demonstrate a radiolucent lesion in the proximal humeral epiphysis. MRI confirms the lesion and surrounding bone marrow edema.

Which local complication is highly associated with chondroblastoma and likely causing the profound joint effusion?

. Malignant transformation to chondrosarcoma
. Secondary aneurysmal bone cyst (ABC) formation and severe reactive synovitis
. Invasion into the axillary nerve
. Direct intra-articular seeding of tumor cells
. Avascular necrosis of the humeral head

Correct Answer & Explanation

. Secondary aneurysmal bone cyst (ABC) formation and severe reactive synovitis

Explanation

Chondroblastomas are intensely inflammatory tumors that cause extensive surrounding marrow edema and reactive joint effusions. Additionally, up to 15-20% of chondroblastomas develop secondary aneurysmal bone cysts (ABCs), exacerbating pain and swelling.

Question 3590

Topic: 10. Pathology and Oncology

A 55-year-old male presents with a large, deep intramuscular mass in the vastus lateralis. Core needle biopsy confirms dedifferentiated liposarcoma. Staging scans show no evidence of distant metastasis.

What is the most appropriate definitive management?

. Marginal excision followed by systemic chemotherapy
. Amputation at the hip joint level
. Wide surgical excision and radiation therapy
. Primary radiation therapy without surgical intervention
. Isolated limb perfusion with TNF-alpha

Correct Answer & Explanation

. Marginal excision followed by systemic chemotherapy

Explanation

Dedifferentiated liposarcoma of the extremity is a high-grade soft tissue sarcoma. The gold standard for localized high-grade extremity soft tissue sarcoma is wide surgical resection (negative margins) combined with neoadjuvant or adjuvant radiation therapy to optimize local control.

Question 3591

Topic: 10. Pathology and Oncology

A pathologist is evaluating a curettage specimen from a distal femur epiphyseal lesion. The differential diagnosis is primarily between chondroblastoma and giant cell tumor of bone. Which of the following combinations of immunohistochemical markers and genetic mutations is highly specific for chondroblastoma?

. CD34 positivity and t(X;18)
. H3F3A G34W mutation and negative S-100
. Positive S-100 and H3.3 K36M mutation
. SOX9 negativity and MDM2 amplification
. Desmin positivity and t(2;13)

Correct Answer & Explanation

. Positive S-100 and H3.3 K36M mutation

Explanation

Chondroblastomas are of cartilaginous origin and express S-100. More specifically, recent molecular pathology has identified the H3.3 K36M mutation (a histone H3.3 gene mutation) as highly specific for chondroblastoma, differentiating it from giant cell tumor of bone (which has the H3F3A G34W mutation).

Question 3592

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with chronic right knee pain. Radiographs reveal a well-circumscribed, lytic lesion with a thin sclerotic rim located centrally in the distal femoral epiphysis. Biopsy demonstrates mononuclear cells with longitudinal nuclear grooves and scattered multinucleated giant cells within a background of pericellular 'chicken-wire' calcification. What is the most appropriate primary surgical treatment for this lesion?

. En bloc resection with endoprosthetic reconstruction
. Extended intralesional curettage, burring, and bone grafting
. Neoadjuvant radiation therapy followed by marginal excision
. Cryoablation without mechanical curettage
. Observation with serial MRI every 6 months

Correct Answer & Explanation

. Extended intralesional curettage, burring, and bone grafting

Explanation

The clinical and histologic findings are diagnostic of chondroblastoma, a benign but locally aggressive epiphyseal tumor. Extended intralesional curettage with high-speed burring and filling the defect with bone graft or cement is the standard of care to minimize recurrence while preserving the joint.

Question 3593

Topic: 10. Pathology and Oncology

A 45-year-old male presents with a painless, deep thigh mass. MRI reveals a multinodular intramuscular mass with high T2 signal and linear septations. Core needle biopsy confirms myxoid liposarcoma. Which of the following chromosomal translocations is most characteristic of this tumor?

. t(X;18) (p11;q11)
. t(11;22) (q24;q12)
. t(12;16) (q13;p11)
. t(2;13) (q35;q14)
. t(9;22) (q22;q12)

Correct Answer & Explanation

. t(12;16) (q13;p11)

Explanation

Myxoid liposarcoma is classically associated with the t(12;16) translocation, which results in the FUS-DDIT3 fusion gene in over 90% of cases. Identifying this translocation is crucial for definitive diagnosis and helps differentiate it from other myxoid soft tissue tumors.

Question 3594

Topic: 10. Pathology and Oncology

A 15-year-old male undergoes extended curettage of a proximal humeral epiphyseal lesion confirmed as chondroblastoma.

During his 2-year follow-up, a routine chest CT reveals a solitary 1.2 cm pulmonary nodule. A biopsy of the nodule shows identical histology to the primary bone tumor. What is the most appropriate management?

. Palliative multi-agent chemotherapy
. High-dose external beam radiation therapy to the chest
. Surgical resection of the pulmonary nodule
. Initiation of long-term Denosumab therapy
. Observation with serial CT scans every 3 months

Correct Answer & Explanation

. Surgical resection of the pulmonary nodule

Explanation

Chondroblastoma can occasionally produce 'benign' pulmonary metastases, occurring in 1-2% of cases. These metastases typically behave indolently, and surgical resection of the lung nodules is frequently curative, providing an excellent long-term prognosis.

Question 3595

Topic: 10. Pathology and Oncology

An asymptomatic 60-year-old woman undergoes imaging for a suspected hematoma, revealing a deep intramuscular lipomatous mass in her anterior thigh measuring 12 cm. Core needle biopsy demonstrates mature adipocytes with focal hyperchromatic nuclei and nuclear atypia. Molecular testing is most likely to show amplification of which of the following?

. MYC
. MDM2
. EWSR1
. SYT-SSX
. COL1A1-PDGFB

Correct Answer & Explanation

. MDM2

Explanation

Well-differentiated liposarcoma (atypical lipomatous tumor) is characterized by the amplification of the MDM2 and CDK4 genes on chromosome 12q13-15. This molecular finding reliably distinguishes it from benign deep lipomas.

Question 3596

Topic: 10. Pathology and Oncology

A 32-year-old female presents with a slowly enlarging, firm mass in her posterior thigh.

Histology shows uniform spindle cells in a collagenous stroma without significant atypia or necrosis. Immunohistochemistry is strongly positive for nuclear beta-catenin. Given the diagnosis, what is the preferred initial management strategy?

. Radical en bloc surgical excision
. Neoadjuvant radiation therapy followed by wide excision
. Active observation with serial imaging
. Above-knee amputation
. Doxorubicin-based multi-agent chemotherapy

Correct Answer & Explanation

. Active observation with serial imaging

Explanation

The diagnosis is extra-abdominal aggressive fibromatosis (desmoid tumor), confirmed by nuclear beta-catenin positivity. Because these tumors lack metastatic potential, frequently recur after surgery, and often spontaneously stabilize or regress, active observation is now the first-line management for asymptomatic patients.

Question 3597

Topic: 10. Pathology and Oncology

A 65-year-old man presents with a rapidly growing, painful soft tissue mass in his left thigh.

Histological examination reveals highly atypical, bizarre, multinucleated giant cells and lipoblasts with no well-differentiated areas. There are no specific genetic translocations identified. Which of the following statements regarding this subtype of liposarcoma is true?

. It represents the most common subtype of liposarcoma.
. It is characterized by amplification of the CDK4 gene.
. It is an indolent tumor with a low propensity for distant spread.
. It is a high-grade sarcoma with a high rate of early pulmonary metastasis.
. It is pathognomonic for a germline TP53 mutation (Li-Fraumeni syndrome).

Correct Answer & Explanation

. It is a high-grade sarcoma with a high rate of early pulmonary metastasis.

Explanation

Pleomorphic liposarcoma is the least common but most aggressive subtype of liposarcoma. It is a high-grade tumor with complex karyotypes (lacking specific translocations or MDM2/CDK4 amplifications) and carries a high risk of early pulmonary metastasis and poor overall survival.

Question 3598

Topic: 10. Pathology and Oncology

When attempting to differentiate a chondroblastoma from a giant cell tumor of bone on core needle biopsy, which of the following histological or immunohistochemical features is most specific for chondroblastoma?

. Presence of abundant, evenly distributed multinucleated osteoclast-like giant cells
. Detection of a somatic H3F3A G34W mutation
. Diffuse S-100 protein positivity and pericellular calcification
. Spindle cell stroma with more than 10 mitotic figures per high-power field
. High expression of RANK ligand in the mononuclear cells

Correct Answer & Explanation

. Diffuse S-100 protein positivity and pericellular calcification

Explanation

Chondroblastoma is characterized by S-100 positive mononuclear chondroblasts and 'chicken-wire' pericellular calcification. Giant cell tumor of bone, conversely, is characterized by the H3F3A G34W mutation and lacks typical chondroid matrix or S-100 positivity.

Question 3599

Topic: 10. Pathology and Oncology

A 5-year-old boy with metaphyseal chondrodysplasia has recurrent pneumonia. A sweat chloride test is normal, but stool elastase is abnormally low. Radiographs show symmetrical metaphyseal widening primarily affecting the hips and knees. He is at highest risk for developing which of the following complications?

. Osteosarcoma
. Myelodysplastic syndrome or leukemia
. Progressive sensorineural hearing loss
. Atlantoaxial instability
. Pathologic fractures of the diaphysis

Correct Answer & Explanation

. Myelodysplastic syndrome or leukemia

Explanation

This patient has Shwachman-Diamond syndrome, characterized by pancreatic insufficiency and metaphyseal dysplasia. These patients have bone marrow dysfunction and carry a high risk of malignant transformation to myelodysplastic syndrome or acute myeloid leukemia.

Question 3600

Topic: 10. Pathology and Oncology

A 7-year-old boy presents with right groin pain and a limp. Radiographs demonstrate a solitary lytic lesion in the proximal femur with endosteal scalloping. A biopsy is performed, revealing a proliferation of histiocytes with folded, "coffee-bean" nuclei mixed with eosinophils. Immunohistochemical staining will most likely be positive for which of the following pairs of markers?

. CD1a and S-100
. CD20 and PAX5
. Cytokeratin and EMA
. Desmin and MyoD1
. Vimentin and SMA

Correct Answer & Explanation

. CD1a and S-100

Explanation

The biopsy findings describe Langerhans cell histiocytosis (eosinophilic granuloma). The pathologic Langerhans cells characteristically stain positive for CD1a, S-100, and Langerin (CD207).

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