Abstract

Thymic cyst is relatively rare tumor which usually occurs in the neck or mediastinum. Cervical thymic cyst is usually situated laterally and deep to the anterior border of the sternocleidomastoid muscle, simulating a branchial cyst. Thymic cyst of the mediastinum is usually detected incidentally and differential diagnoses include cystic degeneration of thymoma, and cystic teratoma. Two case of a cervical and a mediastinal thymic cysts were reported. The one was a cervical thymic cyst developed slowly growing mass in a 53-year-old male a for 10 years. The cyst was unilocular and measures 5.4x2.9x2.8 cm with columnar or squamous cell linings. The other is a mediastinal thymic cyst developed in a 37-year-old female with chest discomfort for 7 months. The cyst was uniocular and measures 2.8x2.2x2.0 cm. The epithelial lining of the cyst was largely desquamated and covered by macrophages with cholesterol granuloma. Involutional thymic stissue in their walls were noted in both cysts. In both cases presence of thymic tissue in the wall of the cyst thought to be the most important diagnostic feature.

• Keywords: Thymic cyst;Cervical thymic cyst;Mediatinal thymic cyst;Thymus;Cyst;