Initial features and outcome of cutaneous and non‐cutaneous primary extranodal follicular lymphoma

Follicular lymphoma (FL), a typically nodal disease, can arise in extranodal sites in about 10% of cases. The present study aimed to analyse the main differential features of patients with primary extranodal FL. Thirty‐nine patients with primary extranodal FL were identified from a series of 354 patients with FL diagnosed at a single institution and their main clinicobiological features were analysed. Twenty patients (5·6%) had a primary extranodal non‐cutaneous FL, and 19 (5·4%) a cutaneous FL. BCL2+ and CD10+ expression and BCL2/IGHJ@ rearrangement were less frequently observed in cutaneous FL. Absence of ‘B’‐symptoms, early stage, absence of bone marrow involvement and low‐risk Follicular Lymphoma International Prognostic Index (FLIPI) were more frequent in extranodal FL. Five‐year overall survival (OS) was 100%, 83% and 78% for cutaneous, non‐cutaneous and nodal FL, respectively. When stage I patients were analysed separately, no differences were seen in terms of OS. In multivariate analysis, FLIPI was the most important variable to predict outcome. In conclusion, extranodal FLs, particularly cutaneous, have particular clinico‐biological features, which differentiate them from nodal cases. Nevertheless, primary site of the disease is not the main issue to predict outcome.