A 71-year-old woman was admitted to the Jichi Medical School Hospital because of palpitation and easy fatigability. Physical examination revealed no remarkable findings except for anemia. The concentration of serum protein was 5.5 g/dl with 14.6% of M-component, and the value of IgA reached 1,168 mg/dl. Immunoelectrophoresis showed an increase of monoclonal immunoglobulin of IgA-κ type. In the urine, 200 mg/day of Bence Jones protein of κ type was detected. Bone marrow aspiration revealed an increase of a typical plasma cells (21.4% of the total nucleated cells) with needle-shaped cytoplasmic inclusions resembling Auer rods, many of which being randomly distributed in the shape of faggots.
A diagnosis of multiple myeloma with IgA-κ type was established. Although her clinical condition improved with combination chemotherapy, she died from pneumonia.
Needle-shaped cytoplasmic inclusions in myeloma cells were positive for acid phosphatase and negative for staining by Congo red in cytochemistry, and were detected as unstainable defects with the immunofluorescent method using FITC-labeled antisera to human α or κ chain. These cytoplasmic inclusions were identified as hexagonal crystalline structure located outside the Golgi complex and the cisternae of the endoplasmic reticulum by electron micrographs. These results suggested that cytoplasmic inclusions in this case were lysosomal granules.
The characteristics and nature of needle-shaped cytoplasmic inclusions in myeloma cells are discussed.
