A Case of Localized Psoriasis Following Treatment With Iodine-131 For Hyperthyroidism: A Rare Entity

Psoriasis is a T cell mediated inflammatory skin disease, characterized by circumscribed erythematous plaques, covered by silvery micaceous scales. It is known to be triggered by a number of factors including drugs. Drugs may either cause de novo psoriasis or responsible for aggravating preexisting psoriasis. The morphological types can vary from localized or generalized plaque psoriasis to pustular psoriasis and even erythroderma. In this work, we report the case of a 45-year-old male patient who developed localized psoriasis following treatment with Iodine131 For Hyperthyroidism. Based on history, clinical pictures, localized examination and histopathological findings with psoriasiform changes favoured the diagnosis. He was treated with topical steroid with clobetasol propionate (0.05%) and salicylic acid (6%) combination for 1 month following which lesions resolved. We suspected that the mechanism behind this is due to activation of dihydrofolate reductase by radioactive iodine. Further study about the folic acid pathway in psoriasis and the connection between radioactive iodine with psoriasis may be necessary.