Sézary's syndrome (SS) is a leukaemic variant of mycosis fungoides, a cutaneous T-cell lymphoma showing distinct clinical, histological, immunological, and genotypic features. We report a 10-year follow-up of a patient with SS exhibiting unusual features such as granulomatous skin lesions, transformation to a CD30-positive large-cell pleomorphic T-cell lymphoma, and development of myelodysplastic syndrome and review the cases of SS reported in the literature with these unusual and rare complications.