CHRONIC LYMPHOCYTIC-LEUKEMIA WITH 2 CELLULAR-POPULATIONS - A BIPHENOTYPIC OR BICLONAL DISEASE

A case of CLL with two different cellular populations is reported. A 5 0-year-old man was evaluated for persistent absolute lymphocytosis. A peripheral blood smear revealed numerous small lymphocytes (83% of whi te blood cells counted). Frequent Grumpecht shadows were present, too. On bone marrow aspirate smears lymphocytes comprised 85% of the total cells counted, and the bone marrow biopsy showed a mixed nodular-inte rstitial infiltration pattern. The immunophenotypic study showed two d ifferent leukemic populations. The first one (comprising 79% leukemic cells) was CD5+, CD19+, CD10-, CD20+, CD18-, CD22-, CD23++, lambda dim , and FMC7-. The second population (comprising 21% leukemic cells) was CD5+, CD19+, CD10-, CD20+, CD18+, CD22+, CD23+, lambda++, and FMC7+. Gene rearrangement studies detected the germline and one rearranged ba nd in Jk blot with each restriction endonuclease. In the Jh blot the g ermline and two rearranged bands were detected with EcoRI and BamHI an d three rearranged bands with HindIII. The JBI/JBII blot detected only the germline band. The detection of three rearranged bands was interp reted as evidence of the presence of at least two monoclonal populatio ns of cells with the same light chain restriction.