[Multiple myeloma with light chain deposition disease showing needle-like crystal inclusions in plasma cells and macrophages in multiple organs].

A 57-year-old Japanese man was referred to our hospital with the chief complaint of dizziness. Our investigations showed pancytopenia that necessitated bone marrow evaluation; this evaluation revealed plasma cell proliferation that was accompanied by numerous needle-shaped crystal inclusions. Clinical and laboratory examinations were used to establish a diagnosis of multiple myeloma (MM) accompanied by Fanconi syndrome. He was administered treatment with bortezomib, lenalidomide, or thalidomide; however, he died after experiencing upper abdominal pain of unknown etiology. Histopathological examination showed needle-like inclusions in the liver and kidney and macrophages in the bone marrow, suggesting light chain deposition disease (LCDD) that could contribute to multi-organ injury. We report the rare case of a patient with needle-shaped inclusions in MM that caused LCDD.