Epithelioid angiomyolipoma of the kidney - a new case with prominent multinucleated giant cells

Epitheloid angiomyolipoma is a recently recognized tumor entity, of which 9 tumors are documented in the literature. We report a case that occurred in a 19 years old patient. The tumor consisted of epithelioid cells ranging f rom medium sized and polygonal to giant cells with prominent nucleoli. Rema rkably, there were many multinucleated giant cells. Hemorrhage, necrosis, a nd clusters of foamy macrophages were also present. Obvious elements of typ ical angiomyolipoma, especially fatty tissue was not found. Flow cytometry revealed diploid tumor cells with a high S-phase fraction of 9.7%. Melanoma -associated antigen HMB-45 and CD 68 was detected in the epithelioid and sp indle cells. The multinucleated giant cells stained for desmin and KPl,and to a lesser extent for HMB-45 and vimentin. There was no expression of cyto keratin or epithelial membrane antigen. Epithelioid angiomyolipoma often po se problems in diagnosis, particularly with regard to distinction from rena l cell carcinoma. Previous reports in the literature suggest that epithelio id angiomyolipoma may have malignant potential.