Serial CT Findings ofMycobacterium massiliensePulmonary Disease Compared withMycobacterium abscessusDisease after Treatment with Antibiotic Therapy

To present the serial computed tomographic (CT) findings of lung abnormalities in Mycobacterium massiliense pulmonary disease compared with those in Mycobacterium abscessus disease.The institutional review board approved this retrospective study and waived informed consent. Serial chest CT scans of M massiliense (n = 34) and M abscessus (n = 24) pulmonary diseases were retrospectively reviewed. Patients were treated with clarithromycin-containing combination antibiotics regimen, and sputum examinations were performed regularly. CT scans were obtained at the beginning of antibiotic therapy, at the end of 4-week hospitalization, and at the time of 12-month antibiotic therapy.All patients with M massiliense disease had sputum conversion during treatment, whereas 50% of patients with M abscessus disease had sputum conversion. The most common CT findings of M massiliense disease at presentation were cellular bronchiolitis (n = 34, 100%), bronchiectasis (n = 34, 100%), consolidation (n = 33, 97%), nodules (n = 32, 94%), and cavities (n = 15, 44%). These findings were similar in M abscessus disease. Thirty (88%) patients with M massiliense disease had decrease in overall CT score at 12-month therapy, whereas only eight (33%) patients with M abscessus disease had a decrease (P < .0001). Improvement was noticeable in cellular bronchiolitis and cavity in M massiliense disease.Common CT findings of M massiliense diseases overlap with those of M abscessus disease. However, responses to antibiotic treatment are much different; in M massiliense disease, negative sputum conversion is accomplished in all patients and serial CT scans show improvement in most patients.