Endocrine Abstracts

Introduction: Ectopic thyroid tissue (ETT) is a rare entity; it is more frequent in women (80%) and is usually located along the obliterated thyroglossal duct. ETT in the midline is even rarer (1.79%). Incidence of malignancy in this group is lower than in orthotopic thyroid nodules.

Case report: A 40 years old woman, resident in iodine sufficient area, but originating from an iodine deficient area, presented for a midline neck mass. TSH and FT4 were measured by electrochemiluminescence Ultrasound, 131I scintigraphy, computed tomography scan and cytological exam by fine needle aspiration biopsy were performed. There were no compressive symptoms. Clinical examination was normal, except a 3/2 cm supra sternal mass, homogeneous and painless. Thyroid function was normal (TSH=0.71 mIU/l, FT4=14.2 pmol/l), TPO antibodies were positive (94 IU/ml) and calcitonin was normal (1 pg/ml). Neck ultrasound showed a hypoechoic solid nodule 31/16 mm (inhomogeneous with discreet vascularization) which was situated on the median line, below the lower poles of the thyroid gland, but without any contact with those. The thyroid scintigraphy revealed a normal located thyroid with inhomogeneous capture for 131I, and slight uptake in the mass described by ultrasound. Neck CT scan revealed a mass in the inferior cervical region and superior mediastinum. FNAB confirmed thyroid tissue (normal, well- differentiated thyroid follicles, with old and recent bleedings, associated post haemorrhagic resorption areas- old nodular goiter) and did not reveal any evidence of malignancy; surgical excision was scheduled.

Conclusions: Midline neck ectopic thyroid tissue is seen very rarely; it should be considered when we need to investigate a neck mass because it may coexist with a normally located and functioning thyroid gland.