Irregular epithelioid cells in small groups lie in a fibromyxoid backgroud that contains small vessels. Image

The cells are mesothlial and are haphazardly arranged in a cohesive manner. Some glandular appearing lumina are apparent. Image

Small clusters, some of which appear gland like, are seen. In some areas the cells line up and form a glomeruloid shape. Image

Strong nuclear WT-1 staining is evident. Image

calretinin highlights the infiltrating mesothelioma Image

Mesotheliomas can assume a wide range of morphologies, and thus, a broad range of differential diagnoses must be considered (as noted in the above chart).

Epithelioid mesotheliomas are composed of polygonal or round cells with a paracentric nuclei, a small nucleoli and a moderate amount of cytoplasm.