Benign mediastinal teratoma masquerading as a large multiloculated effusion.

Benign mediastinal teratomas are uncommon germ cell tumors often discovered while still asymptomatic. Almost all arise in the anterosuperior mediastinal compartment, and most symptoms, when present, result from compression of adjacent structures. We report a case of a large teratoma arising from the anterior mediastinum that presented a confusing clinical picture of a multiloculated pleural effusion. It was successfully treated by surgical excision, with no long-term recurrence.