Thoracoscopic Resection of a Bronchial Artery Aneurysm Mimicking Mediastinal Lymph Node Metastasis after Surgery for Papillary Thyroid Cancer: A Case Report

INTRODUCTION: Mediastinal lymph node recurrence is frequently encountered during the follow-up after surgery for thyroid cancer. We report a rare case of a bronchial artery aneurysm (BAA) that was preoperatively suspected to be a mediastinal lymph node metastasis based on imaging findings and subsequently treated with thoracoscopic resection. CASE PRESENTATION: A 68-year-old male underwent a total thyroidectomy and neck lymph node dissection for papillary thyroid carcinoma (pT1bN1bM0, UICC Stage II), followed by radioactive iodine ablation as adjuvant therapy. Surveillance CT performed 2 years postoperatively revealed a 30-mm mass in the subcarinal region of the mediastinum. The mass showed peripheral calcification with an internal low-density area. Serum thyroglobulin level was 0.18 ng/mL (within normal limits). PET revealed mild fluorodeoxyglucose uptake with a maximum standardized uptake value of 2.5. These findings were consistent with solitary mediastinal lymph node metastasis. No other findings suggestive of recurrence were identified, leading to the decision to perform thoracoscopic resection of the mediastinal tumor for both diagnostic confirmation and therapeutic intervention. The operative time was 67 min with minimal blood loss, and the patient was discharged on POD 3 without complications. Histopathological examination revealed that the mass was a 25-mm arterial aneurysm with atherosclerotic changes and no evidence of malignancy. CONCLUSIONS: When evaluating a subcarinal mediastinal mass following thyroid cancer surgery, it is important to include vascular lesions, such as BAAs, in the differential diagnosis, although these are rare. This case demonstrates that minimally invasive thoracoscopic resection provides both diagnostic confirmation and therapeutic benefits when preoperative diagnosis remains uncertain.