65 In a surprising medical case, a 22-year-old woman with a history of Graves’ disease (GD) was diagnosed with an ectopic cervical thymoma – a rare type of tumour usually found in the anterior mediastinum but, in this instance, located in the neck. This marks the first documented case of such a tumour occurring in a patient previously treated for GD, adding a new dimension to the understanding of thymic neoplasms in individuals with thyroid disorders. The findings were published in The Journal of Clinical Endocrinology & Metabolism. Thymomas are usually harmless growths that start in the thymic epithelial cells and are mostly found in the anterior mediastinum, the part of the chest that holds the heart, the thymus, parts of the trachea and oesophagus, and other important organs. The occurrence of thymomas outside this region is exceedingly rare, accounting for a small fraction of all cases. While Graves’ disease – a condition characterised by hyperthyroidism due to an overactive thyroid gland – has been associated with thymic hyperplasia, the development of a thymoma in such patients is not commonly observed. This case, therefore, offers a unique insight into the potential, though rare, complications that can arise in GD patients. The patient, who had been diagnosed with Graves’ disease at the age of 11, first noticed a palpable mass in her right anterior neck five months prior to seeking medical attention. Despite its size and location, the mass did not cause any significant symptoms, such as pain, difficulty in breathing, swallowing issues, or voice changes. However, her medical history prompted further investigation, particularly given the potential implications of such a mass in the context of her thyroid disorder. Initial ultrasonography revealed a heterogeneous mass measuring 2.4 x 1.2 x 2.2 cm, located just lateral to the right lobe of the thyroid gland and near the carotid sheath. Given the unusual nature of the mass, a computed tomography (CT) scan was performed, which suggested the possibility of a pathological lymph node. This finding led to a fine-needle aspiration (FNA) biopsy, which yielded cells indicative of thymic tissue, raising concerns about a potential thymoma. Immunophenotyping confirmed the presence of immature T-cells, which are typical of thymic tissue. This supported the initial suspicion of a thymoma growing outside of the thymus. Given the unusual presentation and location of the tumour, surgical intervention was deemed necessary. The patient underwent a right deep jugular node dissection, during which the mass was successfully removed. The tumour, measuring 2.5 x 2.3 x 1.5 cm, was found to be fully encapsulated with no signs of invasion into surrounding tissues, indicating a Masaoka stage I thymoma. Histopathological analysis classified the tumour as a type B2 thymoma according to the World Health Organization’s classification, which typically denotes a moderate risk of recurrence and a slightly more aggressive behaviour compared to other thymoma types. The surgical procedure was without complications, and the patient made a smooth recovery. Given the complete resection of the tumour and the lack of adverse features, adjuvant radiotherapy was not administered. The patient has since been monitored for a year post-surgery, with no signs of recurrence or any other complications. This case contributes to the growing but still limited body of knowledge regarding ectopic thymomas, particularly in the context of autoimmune thyroid diseases like Graves’ disease. Thymomas are diagnosed in approximately 1 to 3 people per million each year, with the majority of cases occurring in individuals aged between 45 and 56 years. Ectopic thymomas represent a mere 4% of these cases, with cervical thymomas comprising about 45% of the ectopic occurrences. The patient in this case is notably younger than the average age of presentation and is the first reported case involving a prior diagnosis of GD. This case shows how important it is to think about ectopic thymomas when looking at anterior neck masses in GD patients, especially those who are in stable euthyroid remission. Even though GD is often linked to thymic hyperplasia, it is still very rare for a thymoma to develop in these patients, especially in an unusual place.