Langerhans' cell histiocytosis in adults.

Three cases of Langerhans' cell histiocytosis with unusual clinical and histopathologic features are described. The first two cases illustrate diagnostic pitfalls that underscore the importance of considering Langerhans' cell histiocytosis in the differential diagnosis of purpuric papular eruptions of the scalp and intertriginous areas, particularly in association with hypothalamic, pituitary, or liver disease. The third case is the first report of Langerhans' cell histiocytosis presenting as a vesicular eruption.