Congenital thymic cysts in children - Mostly misdiagnosed

Background/Purpose: Thymic cysts are rare lesions of the neck and mediastinum that are difficult to diagnose. Often considered inconsequential, these lesions can frequently be symptomatic. In this report the authors contrast their experience with that of the literature. Methods: From 1984 through 1997, the authors encountered 14 patients with this lesion. All cysts were completely excised. Patients that had an acquired cyst of the thymus were excluded from this series. Results: Of the 14 patients ranging in age from 2 weeks to 16 years, seven patients had cervical masses, five had mediastinal masses, and two children had both sites involved. Seven children were symptomatic with wheezing and upper respiratory infection, with cough and fever being the most common clinical features. Investigations included chest radiograph, contrast esophagram, sonography (US) and computerized tomography (CT). Displacement of vital mediastinal or neck structures was observed in eight patients. Only two patients received correct diagnosis before surgery. Successful and complete excision of all cysts was achieved. The cysts were benign and ranged in size from 2 to 22 cm in diameter. Conclusion: Often forgotten, thymic cysts are rare benign lesions that should be considered in the differential diagnosis of cervical and mediastinal masses in children.