Serial CT findings of Mycobacterium massiliense pulmonary disease compared with Mycobacterium abscessus disease after treatment with antibiotic therapy.

PURPOSE: To present the serial computed tomographic (CT) findings of lung abnormalities in Mycobacterium massiliense pulmonary disease compared with those in Mycobacterium abscessus disease.

MATERIALS AND METHODS: 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.

RESULTS: 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.

CONCLUSION: 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.