A unique location of branchial cleft cyst: case report and review of the literature.

Branchial cleft cysts (BCC) are benign lesions caused by anomalous development of the branchial apparatus. This case report describes a 63-year-old woman with a 12 cm×12cm sized cystic mass located anterior to the manubrium sternum and sternum. MRI revealed a cystic lesion with a sinus tracking to the piriform sinus. Postoperative histopathological examination confirmed the diagnosis of branchial cleft cyst. Because of the course of the sinus track, it is believed that this was a fourth branchial cleft cyst. These are the rarest of the branchial anomalies, and extension below the peri-thyroid region is very infrequently described. When this extension occurs, it is always post-sternal into the mediastinum, and the pre-sternal presentation here appears to be unique. A review of the relevant literature was performed to summarize the clinical features of fourth branchial cleft cyst and to identify the best options for diagnosis and treatment.