RESUMEN
Patients with mycosis fungoides (MF) are thought to be at increased risk of melanoma. However, studies addressing surveillance-bias and treatments as a possible confounder are lacking. This retrospective study compared the prevalence and risk of melanoma between 982 patients with MF, and 3,165 patients with psoriasis attending tertiary cutaneous-lymphoma/psoriasis clinics during 2009 to 2018. Melanoma was diagnosed in 47 patients with MF (4.8%; 43 early-stage) and in 23 patients with psoriasis (0.7%) (odds ratio 6.6, p < 0.0001). In 60% of patients, MF/psoriasis preceded melanoma diagnosis. Hazard ratio (HR) for a subsequent melanoma in MF vs psoriasis was 6.3 (95% confidence interval (95% CI) 3.4-11.7, p < 0.0001). Compared with the general population, melanoma standardized incidence ratios were 17.5 in patients with MF (95% CI 11.0-23.9, p < 0.0001), and 2.2 (95% CI 0.6-3.8, p = 0.148) in patients with psoriasis. Narrow-band ultraviolet B was not a contributory factor (HR 1.15, 95% CI 0.62-2.14, p = 0.66). These findings add evidence that patients with MF have a significantly higher risk of melanoma, not only compared with the general population, but also compared with patients with psoriasis. This comorbidity may be inherent to MF.