Endocrine Abstracts

Introduction: It has been documented that autoimmune thyroiditis (AT) predisposes to the development of papillary thyroid cancer (PTC). The presence of chronic inflammation was thought to act as an initiating factor in carcinogenesis. Moreover elevated levels of TSH found in hypothyroid patients with AT were speculated to stimulate follicular epithelial proliferation and thereby promote the development of PCT.

Case: We describe a case of two sisters aged 12 year and 14 year who were diagnosed with multinodular goitre and hypothyroidism secondary to AT two years prior to their referral to tertiary endocrine centre for further investigation and management of their multinodular goitre. They both had positive TPO antibodies and were commenced on levothyroxine. A repeat thyroid ultrasound and fine needle aspiration (FNA) on 14 year-old girl confirmed features consistent with AT (Thy2). She’s remained asymptomatic and stable on the same dose of levothyroxine 75 mcg once daily. However her 12 year-old sister was found to have hypoechoic nodule 7×1.3 mm with multiple hypoechoic foci, compatible with calcification on a repeat thyroid ultrasound. Her FNA raised a high suspicion of PTC. A repeat USS and FNA confirmed metastatic PTC. Therefore she had an elective total thyroidectomy with neck dissection followed by radioactive iodine ablation few weeks later which didn’t reveal pathological uptake. Postoperatively she developed a temporary hypocalcaemia managed with calcium, vitamin D and alfacalcidol, which were gradually weaned down when her PTH recovered and calcium normalised. Moreover her levothyroxine was gradually increased to 125 mcg once daily in order to suppress TSH<0.1 mU/l.

Conclusion: We present an interesting case of two siblings with multinodular goitre and hypothyroidism secondary to AT, one of which developed PTC on a background of thyroiditis. Although PTC is rare in childhood and caused association between AT and PTC remains elusive, based on evaluation of current literature, it would be prudent to rule out malignancy in nodular autoimmune thyroiditis. Therefore it is recommended the thyroid ultrasound and FNA to be performed by experienced radiologist, especially when there is a suggestion of abnormal follicle appearance, which will help to confirm the diagnosis and initiate an early referral for surgical intervention.