Congenital self-healing reticulohistiocytosis--a benign Langerhans cell disease.

An-11-day old girl was seen with brownish nodular lesions scattered over the body with emphasis on the face and scalp. Several lesions had started to involute. Tissue was studied by histopathology, immunohistopathology, routine electron microscopy, and immuno-electron microscopy using cryosubstitution and embedding in K4M. Immunohistopathology revealed that the cells of the dermal infiltrate were Langerhans cells. They expressed Leu 6 and HLA-DR. On routine electron microscopy no Birbeck granules were found in the dermal cells. Birbeck granules in epidermal Langerhans cells were deformed and often situated next to laminated dense bodies. The latter expressed Leu 6 and lysozyme on immuno-electron microscopy. It was concluded that congenital self-healing reticulohistiocytosis is a benign Langerhans cell disease in which Birbeck granules are transformed to laminated dense bodies and possibly degraded by lysosomal enzymes.