Unilateral Graves' disease: a case report with concomitant thyroid cancer and systematic review of literature.

Introduction: Unilateral uptake (i.e., increased radiotracer in one lobe) on a thyroid scan in a patient with Graves' disease (GD) is the distinctive feature of unilateral GD (UGD), representing a rare entity and variant of GD with few documented cases to date. Considering the diagnostic and therapeutical implications of the knowledge of this form of GD, this study was designed to bring more light on the UGD entity within the bilobar thyroid gland.

Evidence acquisition: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed in reporting this systematic review. We developed a search strategy combining terms for Graves or Hyperthyroidism and unilateral systematically and searched PubMed from inception through August 25, 2024. The inclusion criteria were: 1) patients with Graves' hyperthyroidism due to a unilateral involvement in bilobar thyroid gland; 2) articles written in English or any language with an English abstract.

Evidence synthesis: A total of 10 articles met inclusion criteria, in addition to our institutional experience (comprising 27 individual patients in total). All the included studies were case reports/series. Of the 27 patient cases, 20 (74.1%) were female and the mean age of patients was 44.5±10.6 years. 24 patients (88.9%) had overt hyperthyroidism, two (7.4%) subclinical hyperthyroidism, one (3.7%) had initially normal thyroid function. Orbitopathy was present in two cases out of ten (20%). thyrotropin receptor antibodies (TRAb) or thyroid stimulating immunoglobulin (TSI) were positive in 9 cases out of 12 (75%). Right thyroid lobe was involved in 17 cases (63.0%), while the left one in 10 cases (37.0%). Antithyroid drugs ATDs were adopted by 13 patients (68.4%). Four patients (21.1%) underwent surgery, while radioactive iodine (RAI) was performed in two cases. Two cases (15.4%) received a 12-month course of ATD therapy, one of whom recurred. In two out of three cases after hemithyroidectomy hyperthyroidism recurred due to the involvement of the contralateral lobe of the thyroid gland.

Conclusions: Clinicians should be aware of the possibility that GD can present in the bilobar thyroid gland with unilateral gland involvement at scintigraphy. Ultrasound examination is indicated to detect the presence of contralateral thyroid tissue, and to exclude the possibility of a hyperfunctioning nodule or hemiagenesis. When choosing surgery, total thyroidectomy seems to be the appropriate treatment. Further investigation is needed to determine the natural course of UGD and its best management. Future guidelines should consider this form of GD.