Prognostic factors in transformed mycosis fungoides: a retrospective analysis of 100 cases.

Large cell transformation (LCT) in mycosis fungoides (MF) is generally associated with an aggressive clinical course and poor survival, requiring aggressive therapeutic approach. However, a proportion of cases may follow an indolent clinical course. To identify prognostic factors, we analyzed the prognostic relevance of clinical, histologic, and immunophenotypical features in a large cohort of transformed MF patients, including 75 patients with only skin lesions, 19 patients with LCT in skin and lymph nodes, and 6 patients with LCT in lymph nodes only. Multivariate analysis of the total group showed that CD30 negativity, folliculotropic MF, extent of skin lesions and extracutaneous transformation were associated with reduced disease-specific survival (DSS) and, except for CD30 negativity and folliculotropic MF, also overall survival. In a multivariate analysis of 75 patients with only skin lesions at the time of LCT, CD30 negativity, folliculotropic MF and extent of skin lesions were independent parameters for both DSS and overall survival. Using the most discriminating parameters as a prognostic index, in both study groups differences in DSS between patients with 0-1 unfavorable prognostic factor(s) and ≥ 2 unfavorable prognostic factors were statistically significant (P < .001). This prognostic index may be helpful in predicting prognosis and selecting the most appropriate treatment in patients with transformed MF.