[Regressive atypical histiocytosis (or Ki-1 lymphoma of the skin). Presentation of a case with an immunohistochemical study].

: The Authors report a case of regressing atypical histiocytosis (or lymphoma Ki-1 of the skin) a primary cutaneous neoplasm composed by atypical cells resembling histiocytes and proliferating on a inflammatory background. The course is more frequently indolent with healing, although cases with evolution to a systemic lymphoma are referred. The case reported concerns a 52 years old man with multiple lesions in several sites of the body. Ours immuno-histochemical investigations have shown positivity for Ber H2 (equivalent to Ki-1) and for T line monoclonal antibodies in the proliferating cells. Our results agree with the recent reports of literature and therefore that lesion, at first believed as composed by histiocytes, is more probably a neoplasia of the T cells lineage.