IgG4-related disease (IgG4-RD) is a chronic, immune-mediated inflammatory and fibrotic condition that can affect virtually any organ system. While some patients experience involvement of only a single organ, isolated IgG4-RD of the mediastinum is even rarer. This article reports a case of a 48-year-old male patient with isolated IgG4-RD of the middle mediastinum. After a biopsy failed to establish a definitive diagnosis, the patient underwent a right thoracotomy-assisted mediastinal tumor resection via video-assisted thoracoscopic surgery. The tumor was completely resected during the procedure, which lasted 130 minutes, with an estimated blood loss of approximately 50 mL. The patient had a favorable postoperative course and satisfactory clinical outcome. No glucocorticoid or other medical treatment was administered postoperatively, and there was no recurrence during a 6-month follow-up period.
