Clinico-biological features and outcome of patients with splenic marginal zone lymphoma with histological transformation.

We describe 36 patients with splenic marginal zone lymphoma (SMZL) with transformation (SMZL-T), including 15 from a series of 84 patients with SMZL diagnosed at the Hospital Clinic of Barcelona (HCB) and 21 diagnosed with SMZL-T in other centres. In the HCB cohort, the cumulative incidence of transformation at 5 years was 15%. Predictors for transformation were cytopenias, hypoalbuminaemia, complex karyotype (CK) and both the Intergruppo Italiano Linfomi (ILL) and simplified Haemoglobin, Platelet count, lactate dehydrogenase (LDH) and extrahilar Lymphadenopathy (HPLL)/ABC scores (P < 0·05). The only independent predictor for transformation in multivariate analysis was CK [hazard ratio (HR) 4·025, P = 0·05]. Patients with SMZL-T had a significantly higher risk of death than the remainder (HR 3·89, P < 0·001). Of the 36 patients with SMZL-T, one developed Hodgkin lymphoma and 35 a diffuse large B-cell lymphoma, 71% with a non-germinal centre phenotype. The main features were B symptoms, lymphadenopathy, and high serum LDH. CK was observed in 12/22 (55%) SMZL-T and fluorescence in situ hybridisation detected abnormalities of MYC proto-oncogene, basic helix-loop-helix transcription factor (MYC), B-cell leukaemia/lymphoma 2 (BCL2) and/or BCL6 in six of 14 (43%). In all, 21 patients received immunochemotherapy, six chemotherapy, one radiotherapy and three splenectomy. The complete response (CR) rate was 61% and the median survival from transformation was 4·92 years. Predictors for a worse survival in multivariate analysis were high-risk International Prognostic Index (HR 5·294, P = 0·016) and lack of CR (HR 2·67, P < 0·001).