Ustekinumab으로 치료 중인 건선 환자에서 비소각화증과 연관되어 발생한 편평세포암

A 53-year-old Korean woman with known history of psoriasis and treatment with ustekinumab over 16 months, presented with a nontender erythematous plaque with oozing noted on her left sole. Histopathologic examination of the lesion confirmed squamous cell carcinoma (SCC). Although use of ustekinumab was considered a possible risk factor for the development of SCC, administration of ustekinumab was continued per her request following an operation for removal of the SCC. And 19 months later, newly developed multiple hyperkeratotic papules on her soles were diagnosed as arsenic keratosis based on her past history of consumption of Chinese traditional herbal medicine. I concluded that SCC in this patient was not caused by ustekinumab, but was associated with arsenic keratosis. This case emphasizes that screening for risk factors associated with skin malignancies, such as exposure to arsenic or presence of arsenic keratosis, should be performed prior to using biologics in Korean psoriasis patients. (Korean J Dermatol 2017;55(7):440∼444)