Supplementary Material for: Cutaneous Complications Related to Tattoos: 31 Cases from Finland

<b><i>Background:</i></b> Cutaneous complications related to permanent tattoos affect 2-30% of those patients who have tattooed their skin. Little is known about the cases of tattoo complications in Finland. <b><i>Objective:</i></b> The aim of this study was to conduct a retrospective review of a series of Finnish patients with cutaneous tattoo reactions. <b><i>Methods:</i></b> We collected cases of tattoo reactions from the Department of Dermatology at Helsinki University Central Hospital, from members of the Finnish dermatological society and from various other sources (author's private practice, tattooists, professional internet forum). We analysed the demographics, clinical presentation, diagnosis, and microscopic findings on the skin biopsies, and evaluated the therapeutic outcome. <b><i>Results:</i></b> Thirty-one patients (16 men and 15 women, mean age 37.8) were included from 9 cities, mainly from Helsinki. Fifty-two percent (16/31) presented with an allergic tattoo reaction mainly against the red colour (75%, 12/16). Reactions were clinically polymorph ranging from scattered papules or nodules to complete infiltration of a colour. Lesions were itchy and sometimes painful. The reactions were lichenoid, granulomatous, pseudolymphomatous or less specific with a dermal lympho-histiocytic or plasmocytic infiltrate. Other diagnoses included tattoo blow-out (13%), melanoma within a tattoo, naevi within a tattoo (10% each), lichen planus (6%), granulomatous reaction with uveitis, sarcoidosis and dermatofibroma (3% each). Allergic tattoo reactions were mainly treated with local corticosteroid (CS) ointments, CS infiltration or surgical removal. <b><i>Conclusion:</i></b> This review is the largest series of tattoo complications in the Baltic area. It illustrates the wide spectrum of complications. Prospective, controlled therapeutic studies are necessary to assess the best treatment protocols for tattoo allergies and tattoo reaction management in general.