Endocrine Abstracts

Thyroid cancer is the most common endocrine malignancy with an increasing incidence globally predominantly due to the papillary thyroid carcinoma subtype. It is the 17^th and 20^th most common malignancy in females and males respectively. In 2018, Cancer Research UK reported 3865 new cases and 400 deaths. Mortality rates are predicted to continue to rise in the UK with an estimated rate of 1 per 100,000 deaths in 2035. We present a 42-year-old female who presented with a 3-year history of lethargy, tiredness, poor concentration and hair loss. She had a history of iron deficiency anaemia previously requiring iron transfusions. On clinical examination and neck palpation rather tender and prominent thyroid isthmus noted. She was biochemically euthyroid with TSH 3.65 mU/l (range 0.27-4.2 mU/l), free T4 13.15 pmol/l (range 12-22 pmol/l) and free T3 4.7 pmol/l (range 3.1-6.8 pmol/l). Other blood tests showed vitamin D deficiency and an iron deficiency anaemia. Thyroid ultrasound (US) identified a large heterogenous exophytic left paracentral isthmus thyroid nodule measuring 2.1 x 1.1 cm with moderate vascularity within the nodule, classified as U3. Fine needle aspiration cytology (FNAC) described a colloid nodule (Thy2) with no malignant features seen. The management options were jointly discussed with the patient; do nothing, surveillance with repeat US and FNAC or referral for surgery. The patient opted for repeat US performed four months later which showed the nodule had slightly increased in size to 2.4 x 1 cm with significant heterogenicity within the solid and cystic components and moderate vascularity, classified again as a U3 nodule. Repeated FNAC was Thy2 with no malignant cells seen The options of doing nothing, repeated radiological surveillance or surgery were discussed further with the patient and she opted to undergo a left hemithyroidectomy. Histology revealed a 1.1mm focus of papillary thyroid carcinoma (pT1a) within the nodule. She recovered well post-operatively and thyroid function showed TSH 6.64 mU/l, FreeT4 11.2 pmol/l and Free T3 4.3 pmol/l for which she has been started on levothyroxine.

Conclusion: UK guidelines recommend an ultrasound (U) graded radiological examination in patients with thyroid nodules which then determines the patients who require fine needle aspiration cytology to aid diagnosis. This case highlights that thyroid nodule size, particularly if there has been an increase, may correlate with malignant potential. This has been emphasised in the American Thyroid Association management guidelines, but does not feature within UK guidelines.