Mature cystic teratoma of the lung.

Intrathoracic teratomas are usually seen in the mediastinum; they rarely occur in the lung as intrapulmonary teratomas. The criteria for pulmonary origin are the exclusion of a gonadal site or other extragonadal primary sites and the exclusive origin of the tumour from the lung. Lung teratomas, for reasons unknown, commonly involve the upper lobe. Here, we report the case of a mature cystic teratoma (dermoid cyst) in the right middle lobe of the lung in a 22-year-old man. We present the clinical and radiological features, as well as histopathological findings, and discuss the relevant literature.