Definitive Bronchoscopic Photodynamic Therapy for Low-grade Endobronchial Mucoepidermoid Carcinoma Adjacent to the Carina

• Definitive bronchoscopic management achieved durable control of a low-grade endobronchial PMEC. • A carina-adjacent lesion was successfully treated while preserving airway anatomy and avoiding surgery. • One treatment course of Hiporfin-based PDT after electrosnare resection achieved biopsy-supported remission for over 3 years. • This case supports PDT as a potential initial local treatment option in carefully selected superficial low-grade endobronchial PMEC. • Structured bronchoscopic surveillance with repeated site-directed biopsies confirmed sustained complete response. Pulmonary mucoepidermoid carcinoma (PMEC) is a rare salivary gland-type primary lung malignancy arising from the tracheobronchial submucosal glands. Although surgery remains a standard curative option, carefully selected low-grade localized endobronchial lesions may also be amenable to definitive bronchoscopic local treatment. We report a 40-year-old man with compensated liver cirrhosis (preserved liver function) who presented with a 1-year history of cough. Chest computed tomography revealed an endobronchial lesion (∼10 mm) in the left main bronchus approximately 1 cm distal to the carina. 18F-FDG PET/CT showed no nodal or distant metastasis. Pathology confirmed low-grade PMEC (Ki-67 ∼5%), and MAML2 break-apart fluorescence in situ hybridization (FISH) was positive (split signals in 23% of analyzed nuclei). After multidisciplinary discussion, an initial airway-preserving definitive bronchoscopic strategy was selected because the lesion was small, low-grade, and apparently confined to the bronchial lumen, with surgery reserved as a salvage option if local control could not be achieved. The visible tumor was removed by endoscopic electrosnare resection, followed by one treatment course of photodynamic therapy using a hematoporphyrin derivative photosensitizer (Hiporfin, 2 mg/kg, Chongqing Milelonge Biopharmaceutical Co., Ltd., China) and 630-nm laser irradiation (120 J/cm, 3-cm cylindrical diffuser; Guilin Xingda Photoelectric Medical Instrument Co., Ltd., China) at 48 h and 72 h to treat the implantation base and adjacent at-risk mucosa. Complete endobronchial clearance was achieved with preservation of airway anatomy. Follow-up bronchoscopy and chest imaging at 1, 3, 9, 24, and 36 months demonstrated sustained complete response without recurrence or metastasis; site-directed mucosal biopsies at each visit showed no tumor cells. This case adds to the limited literature supporting bronchoscopic PDT as a potential initial local treatment option in carefully selected patients with localized low-grade endobronchial PMEC, particularly when airway preservation is desirable.