A case of primary cystic mediastinal hemangiopericytoma.

We describe a 35-year-old man with a primary cystic mediastinal hemangiopericytoma who presented with the complaint of progressive dysphagia for 6 months. The computed tomography and magnetic resonance imaging findings revealed that a well-defined, fluid-filled mass (measuring approximately 10 x 10 cm) was located posterior to the heart and inferior to the carina of the bronchus. Tumor puncture showed translucent yellow fluid with normal concentrations of carcinoembryonic antigen, squamous cell carcinoma-related antigen, and carbohydrate antigen 19-9 and a high concentration of carbohydrate antigen 125. After removal of the tumor, microscopic examination revealed a malignant hemangiopericytoma. To our knowledge, this is the first case of a primary mediastinal hemangiopericytoma with cystic formation. Moreover, we showed the specific biochemical findings of the cystic fluid that were useful for differentiation from other cystic mediastinal tumors.