Non‐Secretory or Low‐Secretory Myeloma with Intracellular Kappa Chains

Abstract

ABSTRACT. This report concerns six cases of multiple myeloma characterized by either no demonstrable monoclonal immunoglobulin in plasma or urine or by trace amounts (≤0.1 g/***1) of monoclonal kappa chains in the urine. In all cases there was an infiltration of the bone marrow by plasma cells containing kappa chains but no heavy chains. A retrospective analysis was made of 126 consecutive cases of Bence Jones myeloma. The number of kappa and lambda cases was approximately the same. AH cases secreting ≤0.1 g light chains per 1 urine were of kappa type. This contrasts with a kappa/lambda ratio of 1.4‐1.9 among reported series of M‐components containing both heavy and light chains. A review of reported cases of non‐secretory myeloma revealed a preserved capacity for Ig synthesis in the majority of cases and among these a preponderance of kappa chain producing clones. These observations might be explained by a higher tendency for kappa chain producing cells to mutate to low secretors or to cells producing abnormal light chains which are catabolized rapidly. The clinical data from our patients do not indicate a more pessimistic prognosis in non‐ or low‐secretory myeloma, than in other cases of multiple myeloma.

Outcome and characteristics of non‐measurable myeloma: A cohort study with population‐based data from the Swedish Myeloma Registry

“…10 We could not conclude what type of light chain was dominant in non-secretory MM since this was only reported in six patients (kappa 50% [n = 3] vs lambda 50% [n = 3]), which differed from earlier reports with kappa dominance. 24 In oligo-secretory MM, we saw no difference compared to secretory MM, (kappa 61% [n = 85] vs 64% [n = 2028] and lambda 39% [n = 55] vs 36% [n = 1135], P = .4119), which was consistent with earlier findings for non-secretory MM. 25 Interestingly, Ig G M protein was less frequent in oligo-secretory than in secretory MM.…”

Comparable Outcomes in Nonsecretory and Secretory Multiple Myeloma after Autologous Stem Cell Transplantation

“…(12–14) In the majority of the patients with non-secretory myeloma, immunoflourescence studies reveal monoclonal protein in the cytoplasm of the plasma cells suggesting defects in secretion or rapid degradation of the protein as a common mechanism (“non-secretors”). (4, 5, 8) Mutations involving the immunoglobulin chains can also result in the inability of cells to secrete the protein. (15–17) Only a small proportion of patients after detailed plasma cell analysis fail to demonstrate any evidence of immunoglobulin heavy or light chain production.…”

“…(1, 3) A cytoplasmic M-protein can be identified by immunohistochemistry in nearly 85% of these patients. (8) With increasing sensitivity of detection of M-protein, the diagnosis of true NSM is decreasing. (9) This is especially true with the introduction of immunoglobulin free light chain assay that is capable of detecting small elevations in monoclonal free light chain, which would otherwise have escaped detection by immunofixation techniques.…”

Raised ?2-Microglobulin as a Surrogate Marker in Non-Secretory Multiple Myeloma

“…According to some previous studies available in literature, most cases of non-secretory multiple myeloma are producers. Other studies proposed that even if the immunoglobulins are secreted, they are being rapidly degraded 3 . More sensitive tests like immunoelectrophoresis, immunofixation may help in detecting M proteins leading to recategorizing of some of the non-secretory cases into typical multiple myeloma.…”

“…Cardiovascular, respiratory, abdomen, musculoskeletal and genitourinary system examination was unremarkable. Investigations revealed hemoglobin of 8.4 gm/dl, a total leukocyte count of 4400/mm 3 , ESR-24, platelet count was 1.5 lacs/mm 3 , peripheral blood film showed microcytic hypochromic anemia without any atypical cells or hemoparasite. The X-ray of chest, electrocardiogram, and fundus examination were normal.…”