Benign vasoformative tumor composed of endothelial cells.
Cystoscopy shows bluish nodular bladder lesion; can be multifocal.
Mostly are cavernous type and tumor cells lack cytologic atypia (image A).
Some lesions may represent vascular malformation.
Immunohistochemistry: like normal endothelial cells, expresses CD31 and CD34 (rarely necessary for diagnosis).
Malignant vasoformative tumor arising from endothelial cells.
Very rare in the bladder.
Histologically, have more atypical spindle and epithelioid cell features (image B).
Immunohistochemistry: expresses CD31 and CD34 (for confirmation).