A case of pulmonary Mycobacterium kansasii presenting with an atypical extensive consolidation involving the entire right lower lobe.

A 76-year-old man with a 3-year history of total gastrectomy presented with extensive consolidation involving the entire right lower lobe on chest CT. Pulmonary Mycobacterium kansasii infection was diagnosed based on sputum and bronchoscopic specimen analyses. Treatment with rifampicin, ethambutol, and clarithromycin was initiated, resulting in improvement of symptoms and radiography findings. M. kansasii infection typically presents with thin-walled cavities in the upper lung lobes. We report a rare case of atypical radiological findings characterized by extensive consolidation in the right lower lobe.