Hemorrhagic thymic cyst presenting with neonatal respiratory distress and mimicking mediastinal teratoma: A case report

Abstract

Introduction Congenital thymic cysts are rare benign mediastinal lesions that are infrequently encountered in neonates. Prenatal detection is uncommon, and hemorrhagic degeneration may further obscure their radiologic appearance, making preoperative distinction from malignant mediastinal tumors challenging. Case Presentation A term neonate with a prenatally detected mediastinal mass developed respiratory distress shortly after birth, requiring neonatal intensive care admission. Chest radiography, ultrasonography, and contrast-enhanced computed tomography demonstrated a large heterogeneous anterior mediastinal mass with cystic and solid components, raising suspicion for a mediastinal teratoma. Owing to persistent respiratory compromise and concern for malignancy, the patient underwent right anterior thoracotomy on the fifth day of life. Intraoperatively, the lesion was found to contain extensive clotted blood and was completely excised. Histopathological examination demonstrated thymic tissue with scattered Hassall corpuscles, extensive intracystic hemorrhage, cystic degeneration, and inflammatory changes, confirming the diagnosis of a hemorrhagic thymic cyst without evidence of malignancy. The postoperative course was uneventful, with marked improvement in respiratory status. Conclusion Hemorrhagic thymic cyst should be considered in the differential diagnosis of anterior mediastinal masses presenting with neonatal respiratory distress.