Dermatofibroma with sclerotic areas resembling a sclerotic fibroma of the skin

BACKGROUND: Dermatofibromas are common benign tumors that occur as single or multiple nodules on the extremities in adults. Sclerotic fibroma of the skin (SFS) is a benign tumor characterized histopathologically by a well-demarcated, non-encapsulated dermal nodule composed of hypocellular, sclerotic collagen bundles with prominent clefts. The pathogenesis of these two conditions is still in dispute. METHODS: We present a case of dermatofibroma with sclerotic areas resembling a sclerotic fibroma of the skin and a review of the literature. RESULTS: The tumor showed a well-demarcated dermal, fibrocollagenous tumor with three different histopathological features. One-fourth of the lesion was consistent with dermatofibroma. Another area adjacent to dermatofibroma revealed hyalinized eosinophilic collagen bundles arranged in the characteristic interwoven pattern with prominent clefts, as is described in sclerotic fibroma of the skin. One-half of the lesion between the dermatofibroma and sclerotic fibroma showed transitional changes from dermatofibroma to sclerotic fibroma. CONCLUSION: According to these findings, the possibility that sclerotic fibroma is an ancient or degenerated stage of dermatofibroma cannot be completely ruled out, but some authors still consider that dermatofibroma and sclerotic fibroma of the skin are completely different neoplasms.