A Rare Cause of Neck Mass in an Adult Woman- Cervical Thymic Cyst - A Case Report

Abstract

Background: Cervical thymic cysts (CTCs) develop from the thymo-pharyngeal duct, representing less than 0.5% of all neck masses. Most of the cases are diagnosed in the first decade of life, being rarely described in adults. The majority of CTCs are located on the left side, the rest develop on the right side or in the midline. The patients present usually with a painless mass, rarely with compressive signs. The mechanisms of CTCs occurrence are still debated, failure of involution of thymopharyngeal duct, arrest in migration or retained thymic tissue during descent, being considered. Case Presentation: We report a case of a 49-year-old woman who presented a left laterocervical mass, with rapid growth over several months. The lump was soft, mobile and painless, no other clinical abnormalities were noticed. The ultrasound described an anechoic nodule of 57/38/63 mm at the inferior pole of the left thyroid lobe, raising the suspicion of a parathyroid cyst or branchial cyst. Contrast-enhanced CT scan confirmed the well-defined, homogeneous cystic lesion of 35/25 mm, located between the trachea and common carotid artery, being delimitated inferiorly by the left brachiocephalic vein. The aspiration of the cyst resulted in 40 ml of water-clear fluid, cytology examination confirmed the absence of thyroid or parathyroid cells. Surgery was performed, the pathological diagnosis confirmed the CTC. Conclusion: Although the thymic cyst is a very rare cause of a cervical mass in adult, the diagnosis should be kept in mind, based on clinical presentation, ultrasound and CT features, respectively aspirated fluid characteristics.