Endocrine Abstracts

Introduction: BCC is a congenital epithelial neck cyst, which occurs due to failure of the second branchial cleft to obliterate during embryogenesis. Development of PTC inside the cyst is extremely rare.

Case description: A 29-year-old female presented to the endocrinology clinic with a gradually increasing painless mass in the right lateral region of the neck, identified on ultrasound examination as an anechoic cyst of size 2×2×5 cm with a smooth wall. Despite repeated biopsies and evacuation of the fluid, the cyst was a recurrent problem. Hence, a decision for surgical removal was made. The histopathological examination revealed a cystic structure with lymphatic weaving in the wall and PTC in both the lumen and lymphatic weaving. Despite no abnormalities were detected in the thyroid on ultrasound, the patient was referred for total thyroidectomy. The histopathological specimen revealed the presence of multifocal PTC within the thyroid, the largest being 1 mm, and one metastatic lymph node. Due to the increased post-surgical thyroglobulin concentration and the suspicion of metastasis to other cervical lymph nodes on ultrasound examination, the patient required two subsequent lymphadenectomies followed by radioiodine therapy to achieve remission. No further recurrence of the disease was observed in a 6-year follow-up period.

Conclusions: In such patients two scenarios should be considered: (i) PTC in BCC is a primary lesion arising from ectopic thyroid tissue concomitant with multifocal PTC of the thyroid or (ii) neck cyst is a cystic degeneration of a metastatic lymph node, while primary site is located in the thyroid. Detection of PTC in BCC requires verification of the thyroid for concomitant neoplastic lesions. Despite normal thyroid on ultrasonography, histopathological examination may reveal the presence of multifocal occult PTC in the thyroid. Therefore, following the diagnosis of PTC in BCC, completion total thyroidectomy should be the recommended procedure.