TRUE T-CELL CHRONIC LYMPHOCYTIC-LEUKEMIA - A MORPHOLOGIC AND IMMUNOPHENOTYPIC STUDY OF 25 CASES

We studied 25 T-cell chronic lymphocytic leukemia (T-CLL) cases collec ted over a 15-year period. Immunophenotypic analysis was performed in each case; 12 cases were evaluated by cytogenetics, and gene rearrange ment studies were performed in 14 cases. The median age was 57 years w ith a male predominance (M:F, 15:10). The median presenting lymphocyte count was 36.3 x 10(9)/L (range, 3.9 to 438 x 10(9)/ L). Fourteen pat ients (56%) had shotty adenopathy and ten (40%) had mild-to-moderate s plenomegaly at presentation; four (16%) had erythematous skin lesions. The lymphocytes were predominantly small; some cases had a minor comp onent of medium-sized cells (<10%). The nuclear:cytoplasmic ratios wer e uniformly high with round to oval nuclei; however, a wide spectrum o f nuclear outlines could be found, ranging from minimally to markedly convoluted. Nucleoli were either absent or small and inconspicuous, Th ese lymphocytes did not have the morphology of prolymphocytes and did not contain cytoplasmic granules. Bone marrow infiltration was general ly in an interstitial pattern; the degree of involvement ranged from 1 5% to 90%. Immunophenotyping showed that the lymphocytes were mature T -cells with a predominant CD4(+) immunophenotype. Three cases displaye d a CD8(+) immunophenotype. The patients were treated with a variety o f chemotherapeutic regimens with only a minimal response observed in t wo of 20 patients. We conclude that T-CLL is an uncommon chronic lymph oproliferative disorder (CLPD) that can be morphologically similar to B-CLL, is distinct from T-prolymphocytic leukemia, and has an aggressi ve clinical course that is refractory to therapy. It may also be diffi cult to distinguish T-CLL from other T-CLPD, especially the leukemic p hase of peripheral T-cell lymphoma and some cases of Sezary syndrome. (C) 1995 by The American Society of Hematology.