Acute disseminated histiocytosis-X: in situ immunophenotyping with monoclonal antibodies

The proliferating skin cells in a case of acute disseminated histiocytosis-X (Abt-Letterer-Siwe disease) confirmed by electron microscopy, were characterized by a panel of monoclonal antibodies using an immunoperoxidase technique. The "histiocytes" were found to stain with OKT-6 (anti-T6) and anti-HLA-DR antibodies. Unexpectedly, slight staining was also observed with Leu 3a (anti-T4) and OKM-1. A proliferative process of T4, T6, HLA-DR, OKM-1 positive Langerhans' cells has not yet been described and may be specific for histiocytosis-X.