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IgA-lambda/IgG-kappa biclonal myeloma in which two clones proliferated in individual sites
1First Department of Internal Medicine, Tokyo Medical University, Shinjuku-ku.
Insights
This study identified a rare case of biclonal myeloma in a 72-year-old man. Two distinct myeloma clones, IgG-kappa and IgA-lambda, were found in different body sites, suggesting independent origins.
Area of Science:
- Hematology
- Oncology
- Immunology
Background:
- Multiple myeloma is a cancer of plasma cells, typically characterized by a single clone producing a monoclonal protein (M-protein).
- Biclonal multiple myeloma, involving two distinct plasma cell clones, is a rare entity presenting diagnostic and therapeutic challenges.
Observation:
- A 72-year-old male presented with low back pain and leg numbness, later found to have a tumor invading the fourth lumbar vertebra.
- Immunohistochemical analysis revealed distinct immunoglobulin heavy and light chain types in myeloma cells from different sites.
Findings:
- Bone marrow myeloma cells were exclusively IgA-lambda type.
- Myeloma cells within the lumbar vertebral tumor were exclusively IgG-kappa type.
- These findings confirm a diagnosis of IgG-kappa/IgA-lambda biclonal multiple myeloma.
Implications:
- The distinct phenotypes and locations of the two clones suggest they arose from two independent transforming events.
- Understanding the clonal evolution in biclonal myeloma is crucial for accurate diagnosis and tailored treatment strategies.
- This case highlights the importance of comprehensive immunophenotyping in complex myeloma cases.
Abstract:
A 72-year-old man was admitted to our hospital because of lumbago and numbness of legs. Tumor invasion at the fourth lumbar vertebra was revealed. Immunohistochemistry using specific antibodies against each heavy and light chain of immunoglobulin revealed that the myeloma cells in bone marrow were all IgA-lambda type whereas they were all positive for IgG-kappa type in a tumor of the fourth lumbar vertebra. These data indicate that the patient had IgG-kappa/IgA-lambda biclonal myeloma. Different phenotypes of M-proteins and distinct proliferating sites for two clones suggest that they may have resulted from two independent transforming events.