Keloidal atypical fibroxanthoma (KAF) has recently been categorized as a variant of atypical fibroxanthoma. This paper will emphasize the importance of including KAF in both clinical and histological differential diagnosis of benign and malignant lesions which exhibit keloidal collagen and will also review the current literature on epidemiology, pathogenesis, histology, immunochemistry and treatments.

Atypical fibroxanthoma (AFX) is an asymptomatic low-grade sarcoma that was first described by Helwig in 1961. Numerous histological variants of AFX have been described, including clear cell, granular cell, chondroid, hemosiderin pigmented, osteoid AFX with osteoclast-like giant cells and sclerotic forms. Keloidal AFX (KAF) is a recently described variant that has often been misdiagnosed. KAF was first mentioned in the study by Welsh in 2006. KAF is a variant of AFX that consists of thick bands of hyalinized keloid-like collagen.

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