Multiple myeloma is a malignant dyscrasia, it is the endpoint on the spectrum of plasma cell dyscrasias and has determined significance. Almost all multiple myeloma develops through transformations from monoclonal gammopathy of undetermined significance. Death is brought about by end-organ failure as a result of antibody deposition.
Diagnostic criteria (CRAB)
- Greater than 10% clonal plasma cells in bone marrow, or any clonal plasma cell population in other tissues.
- Monoclonal gammopathy (>3g/L), except in non-secretory myeloma.
- Evidence of end-organ involvement (see The CRAB criteria).