Massive thymic hyperplasia in an adolescent

Massive thymic hyperplasia (weight, greater than 100 gm) is a rare lesion in adolescents, and most of the anterior mediastinal masses are true neoplasms. We present a case of massive thymic hyperplasia, in which a 680-gm thymus was resected from a 15-year-old boy. We also present the computed tomographic scan appearance of this lesion, which differed from that previously described, and correlate the histological and radiological findings.