Endocrine Abstracts

Toxic adenomas nodules rarely harbour cancer. Fine needle aspiration (FNA) is often not done due to the rarity of these lesions being cancer, the difficulty in interpreting cytology in hyperthyroid patients and the rarely reported instance of precipitating thyrotoxicosis. Here, we present two young Caucasian female patients with toxic adenomas, who underwent hemithyroidectomy and the histology unexpectedly revealed differentiated follicular cancer. The first is a 29-year-old patient who was incidentally found to have a 46 mm left thyroid nodule (U3). She had no other risk factors for thyroid cancer. The biochemistry was consistent with thyrotoxicosis following which she was commenced on carbimazole. The patient opted to have surgery and underwent left hemithyroidectomy when she was euthyroid. The histology confirmed fully excised minimally invasive follicular cancer with capsular and lymphovascular invasion (pT2R0). The second is a 13-year-old patient, who was referred to endocrinology with T3 toxicosis. On assessment, she was found to have a large (46 mm) left sided thyroid nodule, which the patient and family were previously unaware of. Once, she was rendered euthyroid with carbimazole, it was decided to surgical excise the adenoma (hemithyroidectomy). Even though the ultrasound had initially shown benign features of the nodule (U2), the histology revealed minimally invasive follicular cancer (pT2R0) with capsular but no vascular invasion. We suggest that while thyroid cancer is rare in patients with toxic adenomas, this should be considered among the differentials especially if there are risk factors for cancer, or suspicious features on ultrasound imaging. A review of literature shows that compared to adenomas in euthyroid patients, patients in this group are generally younger and predominately female. If an FNA is considered, it should only be performed when the patient is euthyroid.