Cutaneous Langerhans cell histiocytosis of the genitalia in the elderly: a report of three cases.

Langerhans cell histiocytosis (LCH) is a disease with a broad spectrum of clinical presentations. All of the variants have in common the proliferation of cells which are morphologically, biochemically, and immunophenotypically indistinguishable from Langerhans cells. A retrospective study of three elderly patients revealed the unique presentation of cutaneous Langerhans cell histiocytosis limited to the genitalia. These cases produced a diagnostic challenge because of their unusual clinical presentation and their morphological similarity to certain other entities, including extramammary Paget's disease and malignant melanoma, which may also show S-100-positive atypical cells. All three cases showed infiltrates of histiocytic-appearing cells with folded nuclei and moderate amounts of cytoplasm which involved the epidermis, dermis, or both. Immunoperoxidase studies using antibody to S-100, CD1a and CD68 in each case showed positive staining.