Endocrine Abstracts

Background: Papillary thyroid carcinoma (PTC) in patients with background Graves’ disease (GD) has been associated with a higher risk of post-operative tumour recurrence. We present a case and review the literature for possible explanations.

Case presentation: A 55-year-old gentleman with GD treated with carbimazole presented 1 year after initial diagnosis with a 3 cm palpable thyroid nodule. Fine needle aspiration cytology (FNAC) was suggestive for malignancy. A total thyroidectomy with prophylactic central-compartment neck dissection was done-stage 3 papillary thyroid cancer (T3N0M0); size of tumour: 4.7×2×2 cm. There was no lymphovascular invasion or features of aggressive histology. He received 150 millicurie of 131-radioactive iodine (RAI) and was started on high dose L-thyroxine, keeping thyroid stimulating hormone (TSH) suppressed. Thyroid-stimulating hormone receptor antibody (TRAb) levels was positive at 3.3 IU/L (NR: <1). 2 years post operatively, a follow-up neck ultrasound revealed prominent lymph nodes. FNAC was positive for malignancy. There were no distant metastases. He had neck dissection followed by RAI.

Discussion: Neoplastic cells of differentiated thyroid cancer, like normal thyroid cells, express functional receptors for TSH. Thyroid stimulating antibodies might play a role in stimulating thyroid cancer growth, invasiveness and angiogenesis by up-regulating vascular endothelial growth factor, placenta growth factor, and their receptors. The antibodies have also been shown to initiate cellular proliferation by suppressing mitochondrial reactive oxygen species levels, preventing apoptosis. Apart from that, different growth factors that probably are produced by the over-stimulated (by TRAb) and hypervascularised thyroid could also affect the growth and metastases of thyroid cancer in patients with GD. Interleukins four and ten, locally produced in thyroid glands affected by GD, also have a strong anti-apoptotic effect on malignant thyrocytes.

Conclusion: A high index of suspicion for tumour recurrence in patients with PTC and concomitant Graves’ disease is necessary.