1. ¹Unità Operativa Ematologia 1, Dipartimento di Ematologia, Ospedale Maggiore, IRCCS, Milan, Italy
2. ²Divisione di Medicina I, Ospedale 'Fatebenefratelli e Oftalmico', Milan, Italy
3. ³Centro di Epidemiologia Ospedale Maggiore, IRCCS, Milan, Italy
4. ⁴Istituto di Anatomia ed Istologia Patologica, Ospedale S Paolo, Milan, Italy

Correspondence: L Baldini, Unità Malattie Linfoproliferative, Unità Operativa Ematologia 1, Centro G Marcora, Ospedale Maggiore, IRCCS, Via F Sforza 35, 20122 Milano, Italy; Fax: +39-02-55033334-80

Received 11 April 2002; Accepted 12 July 2002.

Abstract

We verified the diagnostic and prognostic role of a simplified immunophenotypic classification (IC) in a series of 258 patients (M/F: 1.4; median age: 64 years; median follow-up: 64 months; 75 deaths) with mature B cell lymphoid leukemias (MBC-LL) for whom no histopathological diagnosis was available because of minimal or no lymph node involvement. The IC was based on the reactivity of three pivotal immunophenotypic markers: CD5, CD23 and SIg intensity. On the basis of different expression patterns, we identified four diagnostic clusters (C) characterized by distinct clinico-biological features and different prognoses: C1 (149 patients) identified most classical B cell chronic lymphocytic leukemias (CLL-type cluster; SIg^dim/CD5⁺/CD23⁺); C2, 38 patients whose clinico-hematological characteristics were intermediate between C1 and C3 (CLL-variant cluster; SIg^bright/CD5⁺/CD23^+/-or SIg^dim/CD5^-/-/CD23 indifferent); C3 (16 patients) most situations consistent with mantle cell lymphoma in leukemic phase (MCL-type cluster; SIg^bright/CD5⁺/CD23^-); and C4, 55 cases, most of whom were consistent with leukemic phase lymphoplasmacytic/splenic marginal zone lymphomas (LP/S-type cluster; SIg^bright/CD5^-/+/CD23 indifferent). At univariate survival analysis, prognosis worsened from C1 to C4, C2 and C3 (P = 0.0001), and this was maintained at multivariate analysis (P = 0.006), together with CD11c expression (P = 0.0043), age at diagnosis (cut-off 70 years; P = 0.0008) and platelet count (cut-off 140 10⁹/l; P = 0.0034). Besides recognising the two well-known situations of classic B-CLL and MCL, our IC identified situations with distinct prognostic and/or clinical behaviors.