FOSB and vascular neoplasm: Interestingly, there is diffuse nuclear positivity for FOSB in 96% of cases, a very helpful finding since FOSB is expressed in only a couple of other vascular tumors: epithelioid hemangioma (54% of cases), which is not a histological differential diagnosis of PMHE, and some rare cases of epithelioid angiosarcoma (5%), spindle-cell angiosarcoma (10%), or epithelioid hemangioendothelioma (5%) [104].