Abstract
A school-going child presented with fever and productive cough for a short period, which after laboratory and radiological survey was diagnosed as mediastinal teratoma with lung cavitation. Preoperatively the exact cause of lung pathology could not be established, although more common causes prevalent in this zone such as, tuberculosis and lung abscess were excluded. Surgical treatment was planned and excision of the mediastinal mass with segmentectomy of the right-upper lobe carried out through median sternotomy. Mature teratoma is the most common primary germ cell tumour of the mediastinum accounting for 60-70% of all mediastinal germ cell tumours. On very rare occasions it involves the adjacent lung, usually the left lung, producing secondary changes inviting suspicion of a separate lung pathology. Here we present a rare case of a huge mature mediastinal teratoma with secondary right lung cavitation.