Poikilodermatous mycosis fungoides (MF) is a variant of MF, and its clinicopathological, immunophenotypic, molecular, and prognostic features have not previously been defined in the literature.

The purpose of this study was to improve the data available for this variant of MF thus enabling clinicians to apply the appropriate treatment and follow-up.

In a retrospective single center study we evaluated the clinical, histopathological, immunohistochemical, and molecular characteristics of patients with predominant (>50%) poikilodermatous lesions of MF.

In all, 49 patients were identified. The median age at diagnosis was 44 years (15-81 years). Of 49 patients, 43 (88%) had early stage disease (≤IIA) at diagnosis. No patients had stage IV disease at presentation. A frequent association was coexistence of lymphomatoid papulosis (9/49; 18%). Histopathology review showed a high number of cases with CD8⁺ CD4^– atypical lymphocytes (38%). After diagnosis most patients were treated with expectant or skin-directed therapy. Psoralen plus ultraviolet A therapy was most frequently used and had high response rates (83%). Five (10%) of 49 received systemic therapy. The mean follow-up was 11 years, 10 months (1->40 years). In all, 47 (96%) of 49 patients had stable disease and two (4%) of 49 had progressive disease. No patients died during follow-up.

As a tertiary center our patient cohort may be expected to have more advanced and aggressive disease.

Poikilodermatous MF represents a distinct clinicopathological entity from classic patch/plaque MF. It presents at a younger age and is more frequently associated with lymphomatoid papulosis. There is an increased number of cases with predominantly CD8⁺ CD4^– atypical lymphocytes. Overall there is a good response to phototherapy and the overall prognosis appears favorable.