Splenic involvement by a light chain deposition disease (LCDD) associated with sea-blue histiocytosis occurred in a 55-year-old man presenting with LCDD of the kidney without myeloma. Lambda light chain deposits were demonstrated by immunohistochemistry in vessel walls and along the ring fibres of the red pulp sinuses. Accumulation of sea blue histiocytes in the cords was also present. Stiffness of the walls of the red pulp sinuses resulting from light chain deposits may have induced accumulation and destruction of circulating blood cells. Lipid catabolism with production of ceroids may have resulted in lipidic histiocytosis with a sea blue histiocyte pattern.