2018 Volume 32 Issue 7 Pages 804-807
A 72-year-old man exhibited an abnormal shadow on chest roentgenogram during the follow-up of another disease. Chest CT showed a mass measuring 90 mm in the anterior mediastinum. The mass without calcification and fat contained some low density area.
On FDG-PET, the maximal standardized uptake value of the mass was 2.69. The values of serum tumor markers and anti-acetylcholine receptor antibody were not remarkable. Therefore, the preoperative diagnosis favored stage I thymoma. At surgery, a thymectomy with the removal of a part of the right lung and pericardium was performed via a median sternotomy. Histopathologically, the tumor consisted of cystic and solid regions. In a solid region, there were mucus secreting cells, well differentiated squamous epitheliums and intermediated cells. The pathological diagnosis was low grade mucoepidermoid carcinoma and stage II disease. We tried to detect a fusion gene, the so called mammalian mastermind-like gene 2 (MAML2), but the result was negative. The prognosis of a mucoepidermoid carcinoma is reported to depend on the tumor stage and histologic grade. Although this case was stage II disease, a good prognosis is expected due to the complete resection and pathologically low grade.
