LBODP103 Ectopic Thyroid Tissue In A Pediatric Patient After Total Thyroidectomy

INTRODUCTION: Ectopic thyroid tissue is defined as any functional thyroid tissue outside the normal anatomical location. It is rare and occurs with a frequency of 1 in 100,000-300,000. Most commonly, it is located along the normal track of thyroid development along the floor of the primitive gut to the pre-tracheal region of the neck; however, rarely it has been found in other areas. Malignancy is very rare in ectopic thyroid tissue (<1%) and when it occurs, papillary carcinoma is the most common type. Maki et al have reported multiple cases of lateral neck ectopic thyroid tissue in the presence of an orthotopic thyroid gland in the adult population. Only 2 pediatric cases have been reported in the literature so far. CLINICAL CASE: A 11-year-old male presented with concerns of morbid obesity and a neck swelling. He endorsed a previous history of thyroid nodules measuring over 2 cm that were being monitored by his previous endocrinologist. On exam, he was noted to have a goiter. Labs were obtained which indicated normal thyroid function tests (TSH 3. 040 uIU/mL, nl 0.45-4.5 uIU/mL and free T4 0.96 ng/dL, nl 0.93-1.6 ng/dL) and negative anti thyroid antibodies (TPO antibody <9 IU/mL, nl 0-26 IU/mL and thyroglobulin ab <1 IU/mL, nl 0. 0-0.9 IU/mL). His previous medical records revealed that a FNA was completed 2 years prior which was reported as benign. A repeat thyroid ultrasound revealed a multinodular goiter with 5 nodules measuring 3.3 x1.5×1.3cm and 5×6×5mm in the right lobe and 7×6×4cm, 2.4×2.1×1.8cm, and 5×6×5cm in the left lobe. After reviewing different management approaches, the family preferred thyroidectomy. He was referred to general surgery and subsequently underwent total thyroidectomy. Post-operatively, he was started on levothyroxine and calcium carbonate supplementation. The calcium supplementation was subsequently weaned and discontinued. Final pathology was reported as benign. Unfortunately, he was lost to follow up and presented to his primary care provider 6 months post-operatively with continued weight gain and a right sided neck mass. Labs obtained showed an elevated TSH (9.820 uIU/mL, nl 0.45-4.5 uIU/mL) and normal free T4 (1. 07 ng/dL, nl 0.93-1.6 ng/dL). Ultrasound of the neck revealed a 2.5 cm heterogeneous nodule in the right neck adjacent to the thyroid bed, concerning for recurrent/residual disease. FNA was completed and was consistent with normal appearing thyroid tissue. Ultrasound monitoring will continue to assess for change in size and need, if any for surgical removal in the future. DISCUSSION: Ectopic thyroid tissue with an orthotopic thyroid is a very rare finding in the pediatric population. Ectopic thyroid tissue outside of the thyroglossal duct is rare as well. We present an 11-year-old male who underwent thyroidectomy for multiple large thyroid nodules and subsequently developed a new neck mass diagnosed as ectopic thyroid tissue. Presentation: No date and time listed