Surgical management of a huge mediastinal mature teratoma in a 2-year-old girl: a case report.

Background: Mature teratomas are benign cystic tumors that are most commonly asymptomatic. However, in some cases, mediastinal teratomas rupture the lungs and mediastinum with potentially fatal outcomes. Herein, we report a case of a large mediastinal mature teratoma that expanded to the entire left hemithorax in a child with common cold-like symptoms.

Case presentation: A 2-year-7-month old girl visited a family doctor because of cough and rhinorrhea. Chest radiography revealed a large tumor occupying the left hemithorax, necessitating transfer to our institution. Chest computed tomography (CT) revealed a large tumor with calcifications and an encapsulated surface. The lesion was 10.5 cm in size and covered the entire left hemithorax, deviating significantly from the heart. CT suggested a mature mediastinal teratoma. Considering the risk of tumor dissemination, we did not perform a diagnostic biopsy; however, surgery was performed as an oncological emergency. As ventilation and circulation were difficult to maintain during the surgery, extracorporeal membrane oxygenation was performed. During surgery, although the large tumor tightly adhered to the sternum and innominate vein, it could be safely removed from these structures, and the tumor was completely removed through median sternotomy. The pathological diagnosis revealed a benign mature mediastinal teratoma. The patient's postoperative course was uneventful.

Conclusion: As the clinical course of child-specific problems in mature teratomas tends to be severe, a surgical strategy should be meticulously planned to ensure safety.