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A study of intracytoplasmic inclusions in myeloma cells from two patients with multiple myeloma
K Tsuchikawa1, H Yokomichi, I Satoh
1Department of Internal Medicine, National Sendai Hospital.
Abstract:
Two cases of multiple myeloma which showed inclusions within the cytoplasma of myeloma cells were reported. One contained crystalline inclusions which were not stained by May-Grünwald and Giemsa, and the other contained Auer rod-like spindle shaped inclusions which were stained by May-Grünwald and Giemsa and PAS. Both cases were stained intensively by acid phosphatase but they were not stained by Congo red or by thioflavine-T. Moreover, they reacted only with anti-kappa sera in the immunofluorescent study and showed the same structure on electron microscopic observation. Although they showed different staining behaviors according to their compositions, they were considered to be essentially the same. It appears that light chains produced in excess are concentrated and form inclusions through the addition of sugar or digestion by lysosomal enzymes.
Insights
Two multiple myeloma cases revealed cytoplasmic inclusions. These inclusions, formed by excess light chains, showed distinct staining but shared immunofluorescence and ultrastructural similarities.
Area of Science:
- Hematology
- Cell Biology
- Pathology
Background:
- Multiple myeloma is a plasma cell malignancy.
- Cytoplasmic inclusions in myeloma cells are rare and poorly characterized.
Observation:
- Two cases of multiple myeloma presented with distinct cytoplasmic inclusions within myeloma cells.
- One case exhibited crystalline inclusions resistant to May-Grünwald and Giemsa staining.
- The second case showed Auer rod-like spindle-shaped inclusions, positive for May-Grünwald, Giemsa, and PAS staining.
Findings:
- Both inclusion types stained intensely with acid phosphatase but were negative for Congo red and thioflavine-T.
- Immunofluorescence studies confirmed reactivity exclusively with anti-kappa sera for both inclusion types.
- Electron microscopy revealed similar ultrastructural features for both inclusions, despite differing staining properties.
Implications:
- These findings suggest that excess light chain production in multiple myeloma can lead to the formation of cytoplasmic inclusions.
- The inclusions may form through glycosylation or lysosomal enzyme digestion of aggregated light chains.
- Understanding these inclusions offers insights into myeloma cell pathophysiology and potential diagnostic markers.