A Case of Bronchial Diverticulum With Progressive Enlargement and Abscess Formation Successfully Managed by Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration and Antibiotic Therapy.

Bronchial diverticulum (BD) is a rare airway abnormality that rarely enlarges significantly or becomes infected. We report a case of an 80-year-old male with a 15-year history of asymptomatic BD that gradually increased in size and eventually developed into an abscess. Chest computed tomography revealed a cystic lesion adjacent to the left main bronchus with internal fluid and surrounding inflammation. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) enabled safe aspiration and identification of alpha-hemolytic Streptococcus despite the absence of a visible bronchial opening. The infection was successfully managed with antibiotics alone, thereby avoiding surgical intervention. This case highlights the potential for long-term asymptomatic BD to develop infection and demonstrates the diagnostic utility of EBUS-TBNA for lesions adjacent to vital structures. However, further studies are needed to clarify infection risk factors and optimal management strategies for BD.