Ectopic cervico-mediastinal thymoma confirmed by flow cytometric analysis of tumor-derived lymphocytes.

Ectopic cervical or cervico-mediastinal thymomas are very rare and most of them are asymptomatic, except for the presence of a cervical mass. We present the case of a 71-year-old man with an ectopic cervico-mediastinal thymoma threatening superior vena cava syndrome. He had a slight headache and presented with venous dilatation on the chest wall. A computed tomographic scan and magnetic resonance imaging of the chest demonstrated a mass extending from the right neck to the hilum, that indented the trachea and compressed and displaced the brachiocephalic veins anteriorly. Under a right hemicollar incision and median sternotomy, the mass was resected en bloc together with the thymus. The resected specimen was an encapsulated mass measuring 11x7x4 cm. The pathological diagnosis was type AB, non-invasive thymoma, confirmed by 3-color flow cytometry of tumor-derived lymphocytes. Flow cytometry using biopsy material may contribute to the preoperative diagnosis of ectopic thymoma.