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Angiomatoid fibrous histiocytoma(AFH) is a rare cutaneous tumor showing distinctive clinical and histological features. It occurs as a slowly growing nodular or cystic mass of the dermis or subcutis, on the extremities of children and young adults. One of the most characteristic histological features is the presence of irregular blood-filled cystic spaces. The histogenesis of AFH is still controversial, with histiocytes, fibroblasts and endothelial cells all having been proposed as the main proliferating cell. A twenty-year-old woman was seen for a nodular lesion on the right forearm of 1 yeat duration. Initially, the lesion was asymptomatic and had recently increased slightly in size. The excisional biopsy specimen showed a relatively well circumscribed tumor mass in the dermis and subcutis. There were large blood-filled cystic spaces and areas of hemorrhage in addition to the solid sheets of fibroblast-like and histiocyte-like cells. Xanthoma cells, siderophages and Touton type giant cells were also present. On immunohistochemistry, most of the tumor cells strongly expressed histiocyte markers, although some of the tumor cells showed positive reactions for smooth muscle actin, muscle specific actin, desmin, and factor Ⅷ-associated antigen.
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