Thymoma in middle mediastinum that induced tracheal compression—Case report and literature review

BACKGROUND: A thymoma, an epithelial neoplasm of the thymus, mainly occurs in the anterior mediastinum, while few are seen in the middle mediastinum. CASE PRESENTATION: An 83-year-old male was referred for an incidental mass in the middle mediastinum. He had severe dementia and denied symptoms. Our follow-up computed tomography (CT) examinations had revealed the progress of tracheal compression along with tumor enlargement for 2 years. At 85 years old, we performed a thymomectomy via a median sternotomy to avoid complete trachea obstruction. The pathological diagnosis was WHO type A thymoma, Masaoka stage II. One year after surgery, the patient was free of disease. DISCUSSION: Thymomas occurring in the middle mediastinum are rare. In our review of 13 such cases, none were Masaoka stage III or IV, while the majority (9/13, 69.2%) were WHO type A or AB. CONCLUSION: We encountered a thymoma in the middle mediastinum that showed enlargement over a 2-year period, inducing severe tracheal compression. Thymomas can occur widely in pharyngeal pouch-derived locations and should be considered in differential diagnosis of a middle mediastinum tumor.