Mycobacterium avium complex infection which need to distinguish from lung cancer

A 42 year old female was admitted to our hospital due to abnormal shadow on her chest X-ray. She had no symptoms. Chest X-ray and computed tomography (CT) scan revealed solitary nodule on left S10. Bronchofiberscopy was perfomed, but it could not establish pathological diagnosis. Thoracoscopic surgery was performed. It revealed that solitary nodule was Mycobacterium avium infection. Majority cases of Mycobacterium avium infection showed multiple nodules or infiltration shadows on bilateral lungs. But in our case, CT scan showed a solitary nodule, causing differential diagnosis from lung cancer to be difficult.