RESUMEN
Abstract Background Mycosis fungoides is the most frequent form of cutaneous T-cell lymphoma. It is characterized by a chronic, slow, and progressive course, and is associated with mortality rates that depend on several factors, such as clinical staging. A median survival time of up to 13 months is found in patients with advanced stages that require more aggressive treatments, with greater toxicity and higher costs. In Latin America, few prognostic studies of the disease are available. Objective To determine the rate of progression from early stages (IA, IB, IIA) to more advanced stages (> IIB) in patients older than 18 years with mycosis fungoides treated at two medical centers in Colombia between January 1, 2010, and December 31, 2019. Methods Retrospective cohort study with a longitudinal design. Results 112 patients diagnosed with early mycosis fungoides were included. 56.2% were male (n = 63), with a median age of 53 years (IQR 43‒67). The most frequent clinical variant was classic (67.9%; n = 76), followed by folliculotropic (16%; n = 18), and hypopigmented (10.7%; n = 12). The most common first-line treatment was NB-UVB phototherapy (27.7%; n = 31), followed by PUVA phototherapy (25.8%; n = 29%), and topical corticosteroids (25%; n = 28). The global rate of disease progression was 8% (n = 9), with an overall mortality of 12.5% (n = 14). Study limitations Its retrospective design and the lack of molecular studies for case characterization. Conclusions Early mycosis fungoides is a disease with a good prognosis in most patients, with a progression rate of 8% (n = 9).