Malignant Mesothelioma : Solid pattern
Solid pattern of epithelioid malignant mesothelioma consists of nests, cords, or sheets of atypical mesothelial cells. The tumor cells are fairly uniform, round, oval, or polygonal in shape and have moderate to abundant quantity of eosinophilic cytoplasm. The nuclei are large and vesicular with prominent nucleoli. Mitotic activity is not increased. The differential diagnosis in such cases includes solid adenocarcinoma and squamous cell carcinoma. Some cases of solid, poorly differentiated malignant mesotheliomas contain discohesive polygonal tumor cells. In such cases, lymphomas and poorly differentiated carcinomas need to be excluded.