Intrapulmonary teratoma masquerading as hydatid cyst of the lung.

Intrapulmonary teratoma (IPT) is a rare mediastinal teratoma. IPT arise because of abnormal migration of pluripotent stem cells along the developing lung bud. Patients present with chest pain, hemoptysis, and trichoptysis. These tumors have the potential to rupture into adjacent pleura, pericardium, or tracheobronchial tree. The differential diagnosis includes hydatid cyst, fungal ball, lung abscess, and lung parenchymal tumor. We report a case of IPT, which was initially diagnosed as hydatid cyst of the lung due to positive hydatid serology and correlating radiological features. The role of cross-reaction of hydatid antigens with sera of cancer patients needs to be evaluated. Surgical resection of the tumor is advised to avoid complications.