Riedel's thyroiditis in a patient with multiple sclerosis.

Our patient developed Riedel’s thyroiditis soon aft er having an exacerbation of multiple sclerosis (MS). MS has been associated with other autoimmune diseases, including thyroiditis, and both Hashimoto’s thyroiditis and subacute thyroiditis have been described in connection with MS. Yet, we are not aware of any other patient reported to have concomitant MS and Riedel’s thyroiditis. Th e association between MS and Riedel’s thyroiditis remains obscure but may refl ect an autoimmune disorder common to both diseases.