The Koebner phenomenon: Psoriasis in tattoos

摘要

An otherwise healthy 18-year-old man presented with skin lesions that had appeared on 2-week-old tattoos on his forearms. The lesions were neither itchy nor painful. Physical examination showed well-demarcated, mildly erythematous papules with silver scales (Figure 1). He had no family history of skin problems and no previous skin conditions. A skin biopsy was performed and results were compatible with psoriasis (Appendix 1, available at www.cmaj.ca/lookup/suppl /doi:10.1503/cmaj.lll299/-/DCl). Tattoo-induced psoriasis was diagnosed and treated with calcipotriene cream for 4 weeks with satisfactory resolution.Koebner phenomenon was initially reported as the formation of psoriasiform lesions after cutaneous trauma in the uninvolved skin of people with psoriasis. More recently, the definition has been extended to include lesions developed after trauma in people with no pre-existing der-matosis.