Letterer-Siwe disease and subacute monocytic leukemia

We report a case of typical Letterer-Siwe disease associated with a subacute monocytic leukemia in a 75-year-old man. The simultaneous presentation of both diseases is rare. It may be speculated that our patient did not present a chance association of two different processes but a disorder of the Langerhans cell-mononuclear phagocytic system lineage.