Central nervous system histiocytosis X--imaging and responses to chemotherapy.

Histiocytosis X is the term first coined by Lichtenstein in 1953 to describe a heterogeneous group of disorders which is considered now to include Hand-Schuller-Christian disease, Letterer-Siwe disease and Eosinophilic Granuloma of bone. Gagel, in 1941, first described involvement of the central nervous system (CNS) in Histiocytosis X--in this case the hypothalamus and posterior pituitary were the areas principally affected. CNS involvement outwith these areas is rare, generally difficult to diagnose, and little information on treatment is available. In this case we describe a man with cranial histiocytosis X who was treated with intrathecal and systemic chemotherapy and cranial irradiation, and we comment upon the value of magnetic resonance imaging (MRI) in this condition.