SEZARY CELL LEUKEMIA - A DISTINCT T-CELL DISORDER OR A VARIANT FORM OF T-PROLYMPHOCYTIC LEUKEMIA

We report the clinical, ultrastructural, immunophenotypic and virologi cal features of nine cases of a rare type of mature T cell disorder fo rmerly designated Sezary cell leukaemia. All patients presented with l ymphocytosis ranging from 12.7 to 133 x 10(9)/l, bone marrow infiltrat ion, splenomegaly and lymphadenopathy. Skin involvement was absent at presentation but developed as a terminal event in two patients, one of whom showed a pattern of dermal infiltration different from that char acteristic of Sezary syndrome. Cells from eight cases bore a mature T cell phenotype and electronmicroscopy revealed lymphocytes with cerebr iform nuclei resembling Sezary cells. All cases except one were HTLV-I negative. Patients were treated with various chemotherapy regimens bu t with poor outcome, the median survival being 13 months. Laboratory a nd clinical data suggest great similarity between Sezary cell leukaemi a and T prolymphocytic leukaemia (T-PLL), namely co-expression of CD4 and CD8 (3/9 cases), identical chromosomal abnormalities in the three cases studied (isochromosome 8q plus inversion 14 or t(X;14)(q28;q11)) and a remarkable sensitivity to CAMPATH-1H (complete remission of 21 months' duration in one patient), suggesting that this entity could be considered a variant form of T-PLL. The alternative diagnosis of adul t T cell leukaemia/lymphoma could not be excluded in one patient in wh om positive HTLV-1 serology was documented.