The non-Langerhans' cell histiocytoses in childhood.

The cutaneous histiocytoses are best divided in the Langerhans' cell histiocytoses and non-Langerhans' cell histiocytoses. In the former group, the cells react with S100 and CD1a antibodies, while in the latter group they express a variety of macrophage markers. Xanthogranuloma is a frequent childhood tumor and the only common non-Langerhans' cell histiocytosis. Xanthogranulomas contain a mixture of several different types of histiocytes that also appear in more pure forms as both solitary tumors and disseminated processes. The varying histiocyte morphology provides a unifying concept for non-Langerhans' cell histiocytoses.