Regressing atypical histiocytosis. Report of a case.

A patient with a pseudomalignant, histiocytic dermal lesion is reported. Despite a torpid course, the lesion was considered on histologic grounds by several consultants to be malignant. It appears to be distinct from previously reported pseudosarcomas or pseudolymphomas and most closely resembles a recently described condition termed "regressing atypical histiocytosis." The clinical and histopathologic features are summarized.