COEXISTENCE OF AN AUTONOMOUSLY FUNCTIONING THYROID-NODULE IN A PATIENT WITH GRAVES-DISEASE - AN UNUSUAL PRESENTATION OF MARINE-LENHART-SYNDROME

A 44 year-old woman developed hyperthyroidism due to the coexistence o f Graves' disease and an autonomously functioning thyroid nodule (AFTN ). Anti-thyrotropin receptor antibody (TRAb) was strongly positive (83 .2%), and a thyroid scan initially showed diffuse uptake of Tc-99m per technatate in both lobes and further increased uptake in accordance wi th the right lobe nodule. The nodule in the right lobe was histologica lly diagnosed as thyroid follicular adenoma. After she was maintained in a euthyroid state by treatment with Methymazole (MMI), thyroid upta ke of Tc-99m in the nodule became lower and was slightly suppressed by T3 administrations probably due to its dependence on TSH. Subtotal th yroidectomy was performed and she subsequently became euthyroid with n egative TBII activity. It is concluded that she had a coexisting funct ioning nodule with Graves' disease (Marine-Lenhart syndrome) and that the nodule changed from hot to cool along with the anti-thyroid treatm ent, unlike usual cases of this syndrome showing a cold nodule on the initial imaging under the hyperthyroid state. Repeated Tc-99m pertechn atate thyroid scans were helpful in evaluating the reaction of MMI and TSH in both lesions separately in the present case.