Mucoepidermoid carcinoma misdiagnosed as carcinoid tumor in an adolescent managed by parenchymal-sparing bronchial resection: a case report

Introduction and importance: Bronchial mucoepidermoid carcinoma (MEC) is a rare pediatric pulmonary malignancy that is easily overlooked or misdiagnosed as a carcinoid tumor on limited biopsy material, with direct implications for surgical planning. Presentation of case: A 16-year-old male’s symptoms began with a dry cough in January 2025 and progressed to recurrent pneumonia and a persistent productive cough. Imaging and bronchoscopy identified a 15 × 11 mm endobronchial mass in the left main bronchus. Initial biopsy favored carcinoid tumor; immunohistochemistry (IHC) (pan-cytokeratin and MAML2-related protein–positive, neuroendocrine markers–negative) established a diagnosis of low-grade MEC. Parenchymal-sparing wedge resection of the left main bronchus with bronchobronchial anastomosis was performed, achieving R0 resection and pN0 status while preserving the ipsilateral lung. At 1-month follow-up, the patient was asymptomatic with a patent anastomosis; at approximately 9 months postoperatively, he remained clinically well without respiratory symptoms. Clinical discussion: IHC was essential, not merely confirmatory, in distinguishing MEC from a carcinoid tumor, and parenchymal-sparing resection offered oncologic clearance without sacrificing lung parenchyma in a low-grade, node-negative tumor. Conclusion: Recurrent or persistent focal obstructive respiratory disease in an adolescent should prompt consideration of an endobronchial neoplasm, and IHC should be applied routinely to avoid misdiagnosing MEC as a carcinoid tumor. When localized low-grade MEC is confined to the bronchial wall without nodal or distant disease, parenchymal-sparing bronchial resection can achieve complete oncologic clearance while preserving lung parenchyma.