TABLE 1.

Malignant pleural mesothelioma subtype and the associated histologic features (2).

Mesothelioma subtype	Histolopathologic features
Epithelioid	Polygonal, oval, or cuboidal cells arranged in various growth patterns including papillary, tubular/acinar (glandular), tubulopapillary, adenomatoid, deciduoid, solid. Psammoma bodies and necrosis may be present.
Sarcomatoid	Pleomorphic spindled cells arranged in fascicles, whorls or in a haphazard fashion. Heterologous elements (cartilage or bone) may be present. Pleomorphic spindled cells may be entrapped in a dense sclerotic stroma (desmoplastic variant).
Biphasic	Combination of epithelioid and sarcomatoid features.