Pleural dissemination of a mixed ground-glass opacity nodule treated as a nontuberculous mycobacterial infection for 6 years without growing remarkably.

Pulmonary ground-glass opacity (GGO) nodules, which do not grow remarkably, are often observed without treatment. Lung tumors coexisting with inflammation and infection are difficult to diagnose. In this paper, we describe a very rare case of a pulmonary mixed GGO nodule with pleural dissemination. In 67-year-old female, chest computed tomography (CT) showed a mixed GGO nodule that had not grown remarkably in the right lung. For 6 years, the mixed GGO had been treated as nontuberculous mycobacterial infection. She was referred to our department for further investigation of the mixed GGO. We suspected lung cancer and performed lung segmentectomy. The tissue showed pleural dissemination. Coexisting nontuberculous mycobacteria (NTM) delayed the clinical diagnosis. Peripheral lung nodules should be resected or diagnosed as soon as possible, despite manifesting as a slow growth.