Mediastinal mature teratoma with chest pain onset and subsequent perforation: A case report

INTRODUCTION: Mediastinal mature teratomas are often benign, asymptomatic, and incidentally detected during routine chest roentgenography. Enzymes secreted by intestinal or pancreatic tissue in teratomas may lead to mediastinitis or the rupture of adjacent tissues. Herein, we present a case of a patient who experienced sudden onset of chest pain followed by the perforation of a mediastinal teratoma. PRESENTATION OF CASE: A 10-year-old boy presented with chest pain 2 days before admittance to the hospital. Chest radiography showed an anomalous mass shadow, and computed tomography showed an anterior mediastinal mass. Radiography revealed an increase in the mass shadow size and dullness of the left costal phrenic angle. Magnetic resonance imaging revealed pleural effusion and intratumoral haemorrhage, indicating perforation of the tumour. Emergency excision and thymectomy via sternotomy were performed. Pathology confirmed that the mediastinal tumour presented no immature or malignant elements. DISCUSSION: In the present case, the onset of chest pain occurred 2 days before admission, and the initial computed tomography did not reveal tumour perforation. Subsequent chest radiography and magnetic resonance imaging indicated that the tumour had perforated. Surgical tumour excision was planned at the time of admission; however, once perforation was confirmed, emergency surgery was performed. The pleural effusion had high cancer antigen 19-9 levels, and this was expected as the pleural effusion contained pancreatic digestive enzymes. CONCLUSION: The perforation of a mediastinal mature teratoma cannot be predicted based on the symptoms, tumour size, or onset of pain alone. Once perforation is confirmed, surgical excision should be performed immediately.