Echogenic mobile spherules in a cyst as an ultrasound finding in cystic mediastinal teratoma

Mature teratomas are the most common mediastinal germ cell tumor. They are mostly cystic. They are usually asymptomatic and diagnosed incidentally on chest X-ray or CT scan. The diagnosis of teratoma is usually confirmed by CT scan. It shows variable combination of fat, fluid, soft tissue component, and calcification. Ultrasound, a cheap and widely available imaging modality, also provides valuable characteristic appearances of mediastinal teratomas. We present a case of mediastinal cystic teratoma showing characteristic echogenic mobile spherules in the cyst and its brief discussion.