Massive benign thymic hyperplasia in a six-month-old girl: case report.

A 6-month-old girl presented with respiratory symptoms with a large right-sided mediastinal mass noted on diagnostic imaging. Percutaneous biopsy revealed normal thymic tissue. Steroids were administered with no response. Right thoracotomy and complete thymectomy were performed. The specimen weighed approximately eight to ten times normal weight, and histology and flow cytometry revealed normal thymic tissue consistent with benign hyperplasia. The child has remained tumor free for a year since surgery. The rare nature of this tumor leads us to report this case and review the current literature.