Concurrent Sarcoidosis and Melanoma: Coexistence More than by Chance?

of Seve et al. [1] concerning the association of sarcoidosis with melanoma. Increased risk of melanoma among sarcoidosis patients has been reported by earlier studies [2] . However, in our referral center, the incidence of melanoma in patients with sarcoidosis seems to be higher than expected according to previous studies. One possible explanation is the intense exposure to sunlight in our geographic region (Greece) since exposure to ultraviolet light is one of the major risk factors for the development of melanoma. However, one could hypothesize that a common pathogenetic link between the 2 disease entities exists. Mounting evidence in the literature suggests that tumor necrosis factor (TNF) plays a crucial role in the pathogenetic cascade of sarcoidosis; the data suggest that TNF regulates granuloma formation and persistence, while TNFconcentrations are associated with disease activity and prognosis [3, 4] . Additionally, studies have demonstrated an association between TNF gene polymorphisms and the development of sarcoidosis [5] . Interestingly, researchers have reported a positive association of TNF gene polymorphisms and melanoma that may influence disease susceptibility [6] . The data suggest that TNF , which is upregulated by ultraviolet exposure, may contribute to tumor escape from the immune response [7] . Although the aforementioned observations cannot substantiate the latter hypothesis, they provide a novel explanation of the clinical overlap of the 2 diseases which, in our opinion, merits further investigations. In conclusion, patients with sarcoidosis appear to be at significantly increased risk of melanoma, particularly in countries with intense sunlight. Therefore, despite their often favorable prognosis these patients require increased medical attention.