Aneurysmal fibrous histiocytoma(AFH) is a histologic variant of dermatofibroma. The importance of the recognition of AFH as a variant of dermatofibroma lies in the differential diagnosis because the histologic appearance of AFH is uery similar to dermatofibrosarcoma protuberans and other vascular malignancies, such as Kaposis sarcoma and angiosarcoma. A 32-year-old man was seen for a nodular mass on the right popliteal fossa of 4 years duration. The excisional biopsy specimen showed a relatively well circumscribed tumor mass in the detmis. In addition to compact storiform proliferation of spindle cells, there were multiple, irregular, blood-filled, aneurysmal tissue spaces that were devoid of lining of endothelial cells. Also, deposition of hemosiderin was prominent, particularly in the periphery of the aneurysrnal spaces. Immunohistochemical stain for CD34 were negative to most tumor cells. After excisional therapy, there was no evidence of recurrence during the period of ten months follaw-up.