Primary cutaneous follicle centre lymphoma with secondary systemic evolution

Abstract Primary cutaneous follicle centre lymphomas (PCFCLs) are cutaneous proliferation of centrocytes and centroblasts, with a generally indolent evolution. Secondary systemic spread of disease is a rare event, which significantly impairs prognosis. Recently published study by Zhou and al. proposed criteria aiming to predict such evolution at initial stage: (i) rearrangement of Bcl2 , (ii) Ki67% index <30% and (iii) 2 mutations among the CREBBP, KMT2D, EZH2 and EP300.1 genes. We herein report two cases of PCFCLs with systemic evolution. Both patients had been initially diagnosed with localised skin disease, and developed, several years after, a secondary systemic involvement. Skin biopsies at the initial stage and systemic spread were analysed by histology, immunohistochemistry, fluorescence in situ hybridisation, and by DNA sequencing of a panel of 54 genes frequently mutated in lymphomas. Both patients showed no rearrangement of Bcl2 , >30% Ki67% indexes and no mutations among the four proposed genes. These findings run contrary to these previously proposed criteria, highlighting the molecular heterogeneity of this rare disease.