Transformation of Mycosis Fungoides/Sezary Syndrome: Clinical Characteristics and Prognosis

OBJECTIVE: Transformed mycosis fungoides (T-MF) is a rare variant of MF with an aggressive course. In this study, we aimed to describe characteristics of MF/Sezary syndrome (SS) patients with transformation. MATERIALS AND METHODS: Patients diagnosed with T-MF among MF/SS patients between 2000 and 2014 in a tertiary single center were evaluated retrospectively. Demographic data, clinical data, laboratory data, immunophenotype features, response to treatment, survival, and histopathologic features were analyzed. RESULTS: Among 254 MF patients, 25 patients with T-MF were identified (10.2%) and included in the study. The male-to-female ratio was 2.6/1. The median time between MF diagnosis and transformation was 32 months (range: 0-192). Nine (36%) patients were diagnosed initially with T-MF. Advanced disease stage and high serum lactate dehydrogenase (LDH) levels were indicators of poor prognosis and treatment response. Five of the 18 patients with progressive disease had undergone allogeneic hematopoietic stem cell transplantation (allo-HSCT). Allo-HSCT resulted in complete remission in three (60%) patients. Ten (40%) patients died as a result of disease progression. Mean survival time was 25.2±14.9 (2-56) months after transformation. CONCLUSION: Advanced stage, high serum LDH levels, and loss of CD26 and CD7 expression in the peripheral blood are poor rognostic factors in T-MF. Treatment-resistant tumors and nodules should be cautionary for T-MF. Patients with T-MF have a shortened survival. Some patients may respond to first-line treatments. However, the majority of patients who do not respond to first-line therapies also are unresponsive to second or third-line therapies. Allo-HSCT may be an alternative option in patients with T-MF.