Fine‐Needle aspiration cytology of primary renal angiosarcoma with histopathologic and immunocytochemical correlation

Primary renal angiosarcoma is an extremely rare neoplasm, with fewer than 28 cases reported thus far in the English literature. We report for the first time the cytomorphology and immunocytochemistry of this tumor in liquid-based (ThinPrep) fine-needle aspiration (FNA) samples in correlation with the conventional cytologic and histopathologic findings. Conventional smears showed pleomorphic tumor cells focally arranged in structures suggesting anastomosing vascular channels, while ThinPrep smears were less cellular with fewer and smaller tumor cells arranged in clusters or rosette-like formations. Immunocytochemical staining demonstrated positive results for vimentin, CD31, and CD34 and negative staining for epithelial markers, thus supporting the diagnosis of a mesenchymal tumor of vascular origin. The diagnosis of primary renal angiosarcoma was established after histopathologic evaluation of a metastatic liver nodule. The cytological differential diagnosis of this neoplasm and the utility of the ThinPrep method as a diagnostic adjunct to conventional FNA cytology are further discussed.