A new case of Sézary cell leukemia: a morphological variant of prolymphocytic leukemia.

Sir, Sézary cell leukemia (SCL) has been described as a very rare variant of T-prolymphocytic leukemia (TPLL)1-4 with 11 cases reported. T-PLL is usually an aggressive, mature T-cell disorder accompanied by progressive lymphocytosis, splenomegaly, skin lesions and poor outcome.4 However, a few cases with an indolent course have been reported.3 Prolymphocytes of T-PLL show an irregular nuclear shape, deep basophilic cytoplasm with protrusions and a single prominent nucleolus. Several morphologic variants, cases with cerebriform (Sézary-like cells), multilobated (flower-cells) nuclei and other cells which are indistinguishable from the B-PLL small variant have been described.5,6 We report the clinical, ultrastructural, immunophenotypic and cytogenetic features of a SCL detected in a routine screening examination. A 94-year old woman was referred to our division because of a mild lymphocytosis. Peripheral blood count showed: Hb 134 g/L, platelets 263×109/L and WBC 12.2×109/L with 21% segmented neutrophils, 1% band forms, 2% eosinophils, 1% monocytes, 12% lymphocytes and 63% Sézary-like and Lutzner cell types (Figure 1). Blood chemistry values were within normal ranges and serology to HCV, HBV and HIV was negative. Physical examination was unremarkable, without cutaneous lesions, organ or lymph node enlargements. The atypical lymphocytes found in peripheral blood were CD3+, CD4+, CD5+, CD7–, CD8–, and were negative for pan B-cell markers. Electron microscopy revealed lymphocytes resembling Sézary cells with a cerebriform nuclear shape, heterochromatin marginated at the periphery and a prominent nucleolus. Combining conventional cytogenetic studies, using a 72-hour culture of peripheral blood stimulated with PHA, with the cross-species color banding fluorescence in situ hybridization (RxFISH) technology, the following complex karyotype was detected: 46,XX [5] 44⇒45, XX,der(2) t(2;12)(p25;q11),der(5)t(1;5)(q25;q35),-9,-10,-13, der(14)t(6;14)(p21;p11),der(15)t(8;15)(q?;q26),de r(17)t(13;17)(q?;q25),i(17)(q10), add(20) (q13), +21[9]/44⇒45,XX,der(2)t(2;12)(p25;q11), der(3) (1qter→1q32::3q22→3q29: :3p26→3qter), del(5) (q13),+der(8)(8pter→8q21::4q25→4q35: :8p21→8pter), -9,-10, der(14)t(6;14) (p21;p11), 15,-17,i(17)(q10),+21[6]. A diagnosis of SCL was established. The patient has remained stable since her diagnosis 12 months ago. T-PLL is typically associated with a short survival and a resistance to chemotherapy;5 however, a relatively frequent presentation of T-PLL with an indolent course has been described. In a series of 78 cases, Garand et al.3 reported that one third of patients showed isolated, moderate and stable lymphocytosis and among them, 2% had Sézary-like cells, a postthymic phenotype and an abnormal karyotype. The majority of these cases eventually progressed after a mean of 33 months in a stable phase. The progression phase was characterized by B symptoms, splenomegaly, lymphadenopathy, skin lesions, rapidly increasing leukocytosis (often >100x109/L) and thrombocytopenia. Median survival after progression was as short as that of T-PLL (9 months) and response to treatment was very poor. The karyotype of T-PLL is often complex showing multiple rearrangements.7-9 The most significant finding is involvement of chromosome 14 at 14q11, where the TCR α/δ locus is mapped. Structural aberrations at 14q11 are present as inv(14)(q11q32), t(14;14)(q11;q32) or t(X;14)(q28;q11) with similar incidence in all forms of T-PLL. Chromosome 8 abnormalities, usually as i(8)(q10) or t(8;8) (p21;q11), are also frequently observed.10 In the present case, we found a complex karyotype with chromosomal abnormalities common in T-PLL and Sézary syndrome. The clinical, morphologic, immunophenotypic and cytogenetic findings in our patient might support a relationship between SCL and T-PLL as suggested by other authors2,3 and argues against the assumption that SCL is a distinct T-cell disorder.