Circumferential Extramural Spread of Tracheal Adenoid Cystic Carcinoma Causing Unexpected Positive Margin.

Tracheal adenoid cystic carcinoma (ACC) often shows submucosal extension, leading to positive margins. A male patient presented with dyspnea due to an intraluminal tumour arising from the membranous mid-trachea. Rigid bronchoscopy debulking confirmed ACC. In a second-stage operation, circumferential resection of approximately 3.8 cm of trachea with end-to-end anastomosis achieved macroscopic clearance. Intraoperative frozen sections, however, revealed tumour cells within lymphatic channels of the tracheal sheath at the distal cartilaginous-side margin opposite the membranous lesion, precluding further resection because of the limit of safe tracheal length. The anastomosis was therefore completed with anticipated microscopic residual disease, and postoperative radiotherapy from the anastomosis to the carina was delivered. The patient remains recurrence-free at follow-up. This case highlights circumferential extramural lymphatic spread of tracheal ACC and underlines the importance of systematic intra- and postoperative pathological assessment and of considering tracheal sheath and peritracheal tissue in defining resection and adjuvant strategies.