Signet Ring Dermatofibroma, a Rare and Confusing Variant.

Dermatofibroma is a common cutaneous benign fibrohistiocytic tumour, which is usually diagnosed without difficulty. In this report we demonstrated a signet ring variant of dermatofibroma as a rare variant of this common neoplasm together with the possible differential diagnosis.The presence of signet cells in cutaneous neoplasm does not necessarily means malignancy. Signet ring dermatofibroma is a rare variant eliciting differential diagnostic problems which can be solved by careful histopathological examination, searching for the classic areas and the help of immunohistochemistry.