[Mucinous adenocarcinoma of the anterior mediastinum]

The authors report are a rare case of primary mucinous adenocarcinoma of the anterior mediastinum in a 34-year-old Japanese woman. Routine chest radiography revealed an abnormal mass lesion in the left upper mediastinum. Her serum CA 19-9 level was elevated at 299 (normal < 37) U/ml. The large tumor in the anterior mediastinum, 8 cm in diameter, were made of multicystic part with thick wall and thick spetrum and solid part in chest computed tomography (CT). Teratoma was suggested by percutaneous needle biopsy under CT scanning. When the chest was opened through a median sternotomy, adding a left collar incision, we found a hard tumor occupying the superior anterior mediastinum and then resected the tumor together with the left brachiocephalic vein, the left pleura, the pericardium and the left phrenic nerve because of invaded them. Grossly, the tumor was 13 x 10 x 8 cm and weighted 400 g. Pathologic diagnosis was mucinous adenocarcinoma of the anterior mediastinum. No primary cancer lesions were found in pancreas, ovarium, gastrointestinal tract and mammary gland. Microscopic examination showed minimal atypia site in mucinous adenocarcinoma and normal thymic tissues surrounding this tumor. These findings have led this case to conclude the primary tumor of thymus.