Primary Plasma Cell Leukaemia Presenting with a Tri-clonal Gammopathy

Primary plasma cell leukaemia (PCL) is a rare aggressive form of plasma cell dyscrasia characterized by presence of circulating plasma cells in the peripheral blood. It is diagnosed by either the presence of >20% or absolute count >2x109/L of circulating plasma cells. PCL typically presents with a single monoclonal protein but may rarely be non-secretary and its association to multi-clonal gammopathy is rare. We present a rare case of PCL presenting with a tri-clonal gammopathy. A 43-year-old male was found to have leukocytosis (17.55x109/L) with anemia (Hb 8.2 g/dL) and thrombocytopaenia (55x109/L) during basic investigations following minor injury. There were 21% circulating atypical plasma cells with an absolute plasma cell count of 3.69x109/L on the peripheral blood film. The bone marrow aspirate and the trephine biopsy showed >50% abnormal plasma cells confirming the diagnosis of primary PCL. Interestingly, we discovered 3 discrete monoclonal protein bands (one Ig G lambda and two other free-lambda light chains) in the serum by agarose gel electrophoresis and immunofixation. However, capillary electrophoresis and immuno-subtraction reveled only Ig G lambda band. Serum free-light-chain assays showed increased free-lambda (727.7 mg/L; normal 4.23-27.69) with elevated involved/uninvolved ratio (124). His urine was positive for Bence Johns proteins revealing 2 distinct bands in the gamma region on urine protein electrophoresis. He was a diagnosed patient with liver cirrhosis since 2-years back and during the hospital stay developed features of decompensation and expired prior to commencement of specific treatment for PCL. Multi-clonal gammopathies may be transitory and can be observed at presentation or any time during the course of the disease. Association of PCL to a tri-clonal gammopathy is a rare presentation and the correct diagnosis requires use of appropriate analytical technique as capillary electrophoresis may not detect free-light-chains.