Background: Sarcoidosis coexisting with autoimmune disorders, especially with autoimmune thyroid disease (ATD), has been previously described and a common immunopathogenesis has been proposed. We report a series of ten new cases of this association from a large series of patients with sarcoidosis.
Methods: The clinical records of patients diagnosed with sarcoidosis between 1984 and 2006 in the Bellvitge University Hospital were reviewed, and those who were also diagnosed as having ATD were selected. A review of the literature was performed as well.
Results: Ten out of 348 (2.9%) patients with sarcoidosis were identified as having ATD. Sarcoidosis presented as Löfgren's syndrome in 8 patients. Three patients developed Graves' disease, 6 Hashimoto's thyroiditis with hypothyroidism and one had postpartum thyroiditis. In one case, ATD had developed 15 years before sarcoidosis. In the remaining nine cases, sarcoidosis preceded between 4 months to 17 years the development of ATD. In 3 of these cases, sarcoidosis was active when ATD was diagnosed. In one patient, Graves' disease developed immediately after the administration of potassium iodide to treat erythema nodosum.
Conclusions: Sarcoidosis may be associated with ATD at some time of its evolution, either as hyperthyroidism or hypothyroidism. Usually, ATD does not develop during the period of activity of sarcoidosis. We suggest considering personal and family past history of thyroid disease before administering potassium iodide for erythema nodosum in patients with sarcoidosis, as it could trigger hyperthyroidism, especially in patients with iodine deficiency.