Abstract Introduction Oncocytic cystadenomas are rare benign epithelial tumors characterized by papillary growth and lined with oncocytic epithelium that is either columnar or cuboidal with granular eosinophilic cytoplasm. These lesions occur most often in salivary glands and increase in incidence with age. They usually present as well-defined, painless, slow-growing masses composed of cystic cavities with intraluminal papillary projections. Clinical manifestations depend on lesion size and location. Diagnosis relies on endoscopic evaluation and histologic confirmation, with surgical excision as the treatment of choice. While laryngeal cases have been reported, tracheobronchial involvement is exceedingly rare. This case describes a tracheobronchial oncocytic cystadenoma diagnosed by bronchoscopy. Case A 75-year-old man with a history of longstanding chronic obstructive pulmonary disease (chronic bronchitis phenotype), intramucosal esophageal adenocarcinoma previously treated with endoscopic submucosal dissection, and current smoker (80-pack-year history) was referred to the interventional pulmonology service following an incidental finding of a tracheal nodule on low-dose chest computed tomography performed for lung cancer surveillance. The nodule measured 7 mm and was located along the posterior membranous wall of the mid-to-distal trachea. On assessment, the patient endorsed mild exertional dyspnea and a chronic productive cough with clear phlegm. Due to the concern for malignancy, the patient underwent flexible and rigid bronchoscopy with cryobiopsy, debridement, and complete excision of the tracheal nodule without complications. The lesion was covered by normal-appearing mucosa, and the remainder of the airway was normal without endobronchial lesions or secretions. Biopsy findings demonstrated submucosal mucin deposition with detached fragments of benign oncocytic epithelium, consistent with oncocytic cystadenoma arising from tracheal seromucinous glands. Immunostains for cytokeratin 7 and protein 40 highlighted luminal and abluminal cells, supporting a benign biphasic glandular proliferation. Given the benign nature and infrequent occurrence of this tumor, follow-up was planned in one year to ensure no evidence of regrowth. Discussion and clinical importance This is the first case report in literature describing a benign tracheobronchial cystadenoma. While a few cases involving the larynx have been reported, tracheobronchial involvement has not been previously documented. Recognition of this entity is clinically important, as tracheobronchial masses are most often malignant, and misclassification may lead to unnecessary radical interventions. The precise bronchoscopic characterization and complete excision of the lesion achieved in this case demonstrate that minimally invasive techniques can provide definitive treatment while preserving airway integrity. Beyond its novelty, this case challenges diagnostic assumptions and underscores the importance of recognizing rare benign tracheal lesions during cancer surveillance. This abstract is funded by: none
Lopez et al. (Fri,) studied this question.