Assessment of Free Light Chains in the Ascites and Pleural Effusion in Patients with Multiple Myeloma: A Report of 2 Cases

Abstract 5078

A recently developed free light chain (FLC) immunoassay has made possible the quantitative measurement of kappa and lambda FLCs by automated nephelometry. Significant clinical evidence indicates the benefit of serum FLCs in the diagnosis of monoclonal gammopathies, AL amyloidosis and nonsecretory MM patients missed by conventional electrophoretic methods. Reference and diagnostic intervals for FLCs have been developed for serum and urine analyses. FLCs in other bodily fluids may provide a valuable tool in other conditions. For example, kappa FLCs are frequently elevated in the cerebrospinal fluid of patients with clinically suggested multiple sclerosis, and therefore can assist in confirming the diagnosis. Analysis of other bodily fluids for FLCs posts theoretical concerns which relate to a lack of standard reference, as well as, the plausible interference of both cellular and protein content in the fluid with data interpretation.

We report the use of FLC levels in discerning the etiology of recurrent ascite and pleural effusion in 2 patients with a known diagnosis of multiple myeloma. Samples were centrifuged prior to analysis. Other steps of sample processing were based on a standard serum protocol. FLC was analyzed using the FreeLite™ assay (Binding Site) on Beckman Coulter Image analyser.

Patient #1: A 64 year old man was diagnosed with IgG kappa multiple myeloma which was in complete remission according to the International Myeloma Working Group criteria after an induction therapy with lenalisomide and dexamethasone followed by high dose chemotherapy and stem cell transplantation. He presented with abdominal distention and progressive weight loss. A CAT scan of the abdomen showed moderate amount of ascites with no other detectable pathology. Ascite fluid analysis showed 200 nucleated cells/mm³. Differential counts included 8% neutrophils, 30% monocytes, 61% lymphocytes and 1% eosinophils. Serum-ascitic albumin gradient was 0.9 gm/dl. No atypical cells were seen by histological or flow cytometric analyses. Cultures for bacteria and fungi were negative. Serum CA19-9, CEA, AFP and PSA were normal. Serum and protein electrophoresis did not show M spike. Serum kappa FLC and lambda FLC were 10.5 and 6.97 ug/ml, serum K/L FLC was 1.51. Kappa FLC and lambda FLC in ascetic fluid was 12.1 and 8.4ug/ml, respectively. Peritoneoscopy with a peritoneal biopsy showed nodular deposits on the peritoneal lining and pathology confirmed a poorly differentiated adenocarcinoma.

Patient #2: A 62-year old lady was diagnosed with lambda light chain multiple myeloma when she presented with transfusion dependent anemia and renal failure. She was treated with la enalidomide and dexamethasone combination and had stable disease. Her treatment regimen was changed to a bortezomib, liposomal doxorubicin and dexamethasone combination, which she progressed on. The patient was treated with salvage combination of D-PACE as a bridge to high dose chemotherapy and stem cell transplantation. One week after treatment, she developed progressive shortness of breath and confusion. She was noted to be hypoxic at room air and had decreased breath sound on the right side of her chest. Laboratory tests were significant for WBC of 0.3x 10³/mm³. Chest X-ray and CAT scan of the chest showed large amount of pleural fluid with lower lobe atelectasis, and cardiomegaly. An echocardiogram showed a left ventricular ejection fraction of 40% with no wall motion abnormality. The patient was treated empirically with broad spectrum antibiotics and dieresis. The amount of pleural fluid did not improve in 48 hours after treatment. Thoracentesis was performed and pleural fluid kappa and lambda FLCs were <3.00 mg/L and 3221 mg/L respectively. Subsequent cytology and flow cytometric analysis confirmed a monoclonal plasma cell population that expresses CD138, CD38, CD56 and lambda light chain.