Sweet's Syndrome Associated with Graves' Disease

Sweet's syndrome, or acute febrile neutrophilic dermatosis, occurs in association with autoimmune diseases such as Hashimoto's thyroiditis but is rare in Graves' disease, in which all cases are induced by propylthiouracil (PTU). We report a case of Sweet's syndrome in a patient with Graves' disease treated with methimazole (MMI) during three weeks. A 34-year-old man presented with the acute onset of high fever, skin rashes on the whole body, arthralgia, and acroparesthesia. Laboratory results showed leukocytosis and elevated C-reactive protein. MMI first stopped and antibiotics and antihistamine therapy started, but his symptoms dramatically improved after oral prednisolone. Graves' disease has again been treated by MMI because of his aggravated ophthalmopathy. After one year of retreatment with MMI, there has been no recurrence of Sweet's syndrome, supporting that Sweet's syndrome in this case was not related to MMI exposure. To our knowledge, this is the first report of Sweet's syndrome associated with Graves' disease per se but not PTU or MMI use.