Mesothelioma Diagnosis Differential Diagnosis 2

Question 1

Peritoneal mesothelioma must be differentiated from primary peritoneal carcinoma by which IHC finding?

Accepted Answer

Calretinin and WT1 positive vs. PAX8 and ER positive in carcinoma

Answer

Peritoneal mesothelioma stains positive for calretinin and WT1 while primary peritoneal serous carcinoma stains positive for PAX8, ER, and Ber-EP4.

Question 2

Pleural involvement by breast carcinoma can be excluded in favor of mesothelioma by the absence of which markers?

Accepted Answer

ER, GATA3, and mammaglobin

Answer

ER, GATA3, and mammaglobin are breast carcinoma markers; their absence, combined with positive mesothelial markers, supports mesothelioma over metastatic breast cancer.

Question 3

Which rare pleural tumor is composed of lipomatous elements and must be distinguished from mesothelioma with lipomatous areas?

Accepted Answer

Well-differentiated liposarcoma

Answer

Well-differentiated liposarcoma of the pleura contains mature fat and atypical lipoblasts, which distinguishes it from any fat-containing mesothelioma variant.

Question 4

Pleural epithelioid hemangioendothelioma (EHE) is distinguished from mesothelioma by positive staining for which marker?

Accepted Answer

CD31 and ERG (endothelial markers)

Answer

EHE is a vascular tumor that stains for endothelial markers CD31 and ERG, which are absent in mesothelioma.

Question 5

A pleural biopsy showing diffuse large B-cell lymphoma cells would be differentiated from mesothelioma by which finding?

Accepted Answer

CD20 positivity and cytokeratin negativity

Answer

DLBCL expresses B-cell marker CD20 and lacks cytokeratin expression, which is the opposite of mesothelioma's keratin-positive, CD20-negative profile.

Mesothelioma Diagnosis Practice Test

Mesothelioma Diagnosis Practice Test

Mesothelioma Diagnosis Differential Diagnosis 2