Several types of non-secretory myeloma exist.
The first are patients are non–producers, these abnormalities that may have defects in immunoglobulin synthesis.
These patients have all the features of a plasma cell disorder, but are not able to synthesize or secrete a protein.
These patients have no measurable blood protein in the blood or urine, may have significant plasma cell burden and evidence of organ damage, and even free like chain essays will be negative.
The next type of non-secretory myeloma reflect patients whose myeloma produces a protein but has defects in secretion.
Mutations in the immunoglobulin gene can account for lack of secretion in patients with a nonsecrettory myeloma.
These patients have defects in Ig secretion but are able to secrete some low levels of light chains, and have oligisecretory myeloma.
Some patients categorized as non–secretory myeloma , in fact have proteins that are not detected by SPEP or UPEP, but had free light chain only myeloma.
Light chain assay can detect Kappa and lambda light chains.
Non-secretory multiple myeloma (NSMM) is a rare subtype of multiple myeloma characterized by the absence of detectable monoclonal immunoglobulins (M-protein) in both serum and urine.
This variant accounts for approximately 1% to 5% of all multiple myeloma cases.
Diagnosis is often confirmed through bone marrow biopsy, which reveals clonal plasma cell infiltration, and imaging studies that may show osteolytic lesions.
Patients with NSMM may still exhibit clinical features similar to those with secretory multiple myeloma, including bone pain, anemia, hypercalcemia, and renal dysfunction, although renal impairment is less common in NSMM.
Free light chain (FLC) assays can sometimes detect abnormal FLC levels in NSMM patients, aiding in diagnosis.
The pathogenesis may involve genetic mutations that impair the synthesis or secretion of immunoglobulins.
For instance, frameshift mutations in the constant region of immunoglobulin light chains have been implicated.
Treatment for NSMM generally follows the same protocols as for secretory multiple myeloma, including chemotherapy regimens such as bortezomib, cyclophosphamide, and dexamethasone (VCD), etc.
The prognosis and response to therapy are similar to those of secretory multiple myeloma, with some studies suggesting that NSMM patients may achieve higher complete response rates.