Atypical fibroxanthoma and malignant fibrous histiocytoma of the skin.

A case of cutaneous atypical fibroxanthoma (AFX) which metastasized, leading to patient death, is described. This is the third reported case in which a lesion qualified as AFX behaves in such an aggressive manner, comparable with that of malignant fibrous histiocytoma (MFH). Ki-67 proliferation index, p53 and bcl-2 protein expression and DNA ploidy were also consistent with a highly malignant potential. The controversial issue of the biological behavior of AFX and its relationship with MFH is discussed. The authors conclude that MFH and AFX probably represent a single entity with a split biological "personality".