Lateral cervical thymic cyst in a child: a case report.

Background: Cervical thymic cysts are uncommon lesions, rarely considered in the differential diagnosis of neck cysts in children.

Methods: We report a rare case of multiloculated thymic cyst in an 8-year-old boy on the right side of the neck. Perioperative diagnosis was a cystic hygroma. Macroscopic examination showed a cystic mass measuring 6.5 cm in total length. Histopathology of the excised specimen revealed thymic tissue with prominent Hassall's corpuscles associated with multiloculated cyst. The cyst wall is bordered by a flattened or multilayered epithelium, often abraded.

Conclusions: This case is presented here for its rarity and should be included in the differential diagnosis of neck masses in children. So, it's a lesion to be well aware of, particularly by pathologists.