SAT-604 Immunoglobulin G4-related Disease In A Patient With Graves' Disease

Background: IgG4-related disease is a newly emerging fibroinflammatory condition associated with lymphoplasmacytic infiltrates rich in IgG4-positive plasma cells. This disease may involve multiple systems throughout the body, including the thyroid gland. Four categories regarding IgG4-related thyroid disease have been identified so far; as IgG4 related Hashimoto’s thyroiditis, fibrosing variant of Hashimoto’s thyroiditis, Riedel’s thyroiditis and Graves’ disease with elevated IgG4 levels. Clinical case: A-28-year-old female patient referred to our Endocrinology and Metabolism Clinic for preoperative evaluation before recurrent thyroid surgery. She had a diagnosis of Graves’ disease since the age of 20. She received anti-thyroid treatment irregularly for 4 years and had thyroidectomy in 2015 due to new onset features of Graves’ ophthalmopathy. Postoperative thyroid ultrasound revealed residual thyroid tissue (16x19x36 mm right lobe and 12x17x20 mm left lobe) with parenchymal heterogeneity and multiple hypodense nodules reaching 20 mm in diameter with tendency to form clusters. She received levothyroxine replacement with a dose of 75 mcg/day postoperatively. Her fine needle aspiration biopsy from the dominant nodule revealed atypia of undetermined significance. Due to recurrent nodules on the basis of Graves’ disease, suspicious biopsy, and deteriorating Graves’ ophthalmopathy, she was recommended to have reoperation for the residual nodular thyroid tissue. She had severely increased thyroid autoantibodies (TRAB>40 IU/L, Anti-TPO>1300 U/ml, Anti-TG>500 U/ml) and her calcitonin level was negative. She had her second operation at October 2018 and the surgeons encountered with acceptable fibrosis due to recurrent operation. Her pathology revealed autoimmune thyroiditis and immunohistochemical staining showed positive staining with IgG4. She had calcium and levothyroxine replacement postoperatively. Her physical examination and system query were unremarkable except for moderate exophthalmos. Conclusion: Although IgG4 related thyroid disease is an uncommon form of thyroiditis, diagnosis of the disease is increasing due to increased awareness of IgG4 related diseases. IgG4 related thyroid disease may be suspected in patients with Graves’ disease with atypical nodular appearance in the ultrasonographic examination. Identification of IgG4 related thyroid disease in the proper clinical setting is important to increase our understanding of the pathogenesis and the course of the disease to find better management and treatment strategies.