A case of erdheim-chester disease with asymptomatic renal involvement.

Erdheim-Chester disease is a rare non-Langerhans-cell histiocytosis involving bones and multiple organs. Its clinical course can vary, from an asymptomatic state to a fatal disease, with renal involvement being a common cause of death. A 41-year-old man presented with a 10-month history of bilateral lower limb pain. Left perirenal soft-tissue infiltration had been found incidentally two years earlier. No progression of the lesion or deterioration of renal function was observed for a period of two years. At admission, plain radiography and magnetic resonance imaging of the patient's lower limbs showed patchy osteosclerosis. Biopsy of the tibia revealed histiocytic infiltration, which was found to be positive for CD68 and negative for CD1a. This report describes an unusual case of Erdheim-Chester disease involving a stationary course of disease with no specific treatment for a long period of time.