Endocrine Abstracts

Introduction: Multifocal sclerosing thyroiditis (MST) is a recently proposed histopathological diagnosis for thyroidectomy specimens that have ≥1 radial scar-like foci. Despite the inclusion of the term thyroiditis, MST is not related to other well-known types of thyroiditis and does not have a specific clinical presentation.

Case report: A 30-year-old female presented clinic due to thyrotoxicosis. She did not have any symptoms related to thyrotoxicosis. Upon physical examination her thyroid gland was grade 1b diffuse palpable; the remainder of the examination was unremarkable. Her thyroid hormone values were, as follows: sT₃: 6.7 pg/ml (2–4.4 pg/ml); sT₄: 2.4 ng/d/ (0.93–1.7 ng/dl); TSH: 0.06 μIU/l (0.27–4.2 μIU/l). Antithyroid autoantibodies were negative. Thyroid USG was performed in order to determine the etiology of thyrotoxicosis and showed multinodular goiter. A 99m-Tc pertechnetate thyroid scan was performed for functional assessment of solitary thyroid nodules and two cold nodules were noted.

USG-guided fine needle aspiration biopsy of the cold nodules was performed twice. Cytopathological evaluation yielded non-diagnostic findings for both nodules. After improving thyrotoxicosis, total thyroidectomy was performed by a surgeon. The largest diameter of the thyroidectomy specimen was 4.5 cm in the right lobe, 5 cm in the left lobe, and 3 cm in the isthmus. The cut surface showed multiple star-like fibrotic foci, the greatest diameter of which was 0.6 cm between colloidal nodules. Microscopic examination showed entrapping follicular structures with reactive atypia in the periphery of these fibrotic foci. None of the fibrotic foci exhibited neoplastic transformation. Hyperplastic thyroid follicles were observed in the remaining thyroid gland. Based on the histopathological analysis, MST was diagnosed.

Conclusion: Herein we reported a case of MST as a means to increase clinician awareness, as it may be encountered more frequently in the future.