MOLECULAR STUDY OF HAIRY-CELL LEUKEMIA VARIANT WITH BICLONAL PARAPROTEINEMIA

We report an unusual case of hairy cell leukemia variant with IgA and Igc-X biclonal gammopathy exhibiting light chain and a surface immunog lobulin class different from that of the paraproteins. In addition, we documented by gene rearrangement study that the hairy cell leukemia v ariant clone appears independent from the paraprotein-producing cells. The kappa light chain was expressed. on the surface of hairy cell leu kemia variant cells. Southern blot analysis revealed rearrangement of the kappa-light-chain gene and germline configuration of lambda-light- chain gene. We observed significant clinical improvement and reduction in the leukemic infiltrate in the patient after treatment with 2-chlo rodeoxyadenosine (2-CdA). The intensity of the rearranged kappa-light- chain gene band decreased with therapy and increased at relapse withou t significant change of the paraproteins. Previously reported cases of hairy cell leukemia variant with paraproteins are reviewed, and our p atient's contribution to the understanding of this association is stre ssed.