Navigating Middle Lobe Syndrome: Exploring the Impact of Mycobacterium avium

Middle lobe syndrome (MLS) is characterized by recurrent or chronic collapse (atelectasis) of the middle lobe of the right lung. Despite its clinical significance, MLS often goes unnoticed in medical practice. It manifests with obstructive symptoms, either due to external compression or internal causes, commonly stemming from infectious agents such as Mycobacterium avium complex (MAC) or occasionally from tumors. We present a unique case of MLS induced by MAC in an immunocompetent 74-year-old female patient with a history of bronchiectasis. Imaging revealed typical findings associated with MLS. Additional testing confirmed the diagnosis, and the patient was successfully treated. This case presents the opportunity to recognize and correctly treat cases of MLS with infectious etiology.