Non-Langerhan's cell histiocytoses of the skin.

Histiocytic proliferations may be reactive or neoplastic. The neoplastic proliferations (histiocytoses) are subdivided into a few categories. One of these categories is the non-Langerhan's cell histiocytoses (NLCH). Cutaneous NLCH is a heterogeneous collection of conditions which can be sub grouped on the basis of the morphological appearance of the lesional histiocyte into xanthomatized, oncocytic, vacuolated, spindle-cell and polymorphous subtypes. The clinical characteristics and histological appearances of a variety of conditions within each subtype are discussed.