Immunoglobulin free light chains: do they have a role in plasma cell leukemia?

The assay of serum free light chains (FLCs) is established in the diagnosis and prognosis of several plasma cell dyscrasias, but its significance in plasma cell leukemia (PCL) has not been reported so far. PCL is a rare and aggressive disease with a poor prognosis. The authors describe two cases of PCL with divergent clinical profiles where the serum FLC assay was available. Although both patients had greatly elevated serum beta(2)-microglobulin, one patient had much higher levels of serum FLCs and evidence of renal impairment, which were absent in the other; however, the latter, who had multisystem involvement, showed a more rapidly downhill course with early mortality.