Cutaneous T-cell lymphomas (CTCLs) are a heterogeneous group of diseases characterised by abnormal neoplastic T-cell growth in the skin. Mycosis fungoides (MF), the most common CTCL, manifests as erythematous skin patches and/or plaques, tumours or erythroderma. The disease may involve blood, lymph nodes and rarely viscera. Sézary syndrome (SS) is a unique leukaemia/lymphoma syndrome related to MF, which presents with blood and skin involvement at diagnosis. The pathogenesis of MF/SS is …