Solitary pulmonary granuloma caused by Mycobacterium avium-intracellulare complex

OBJECTIVES: To analyse the clinical features and high resolution computed tomography (HRCT) findings of solitary pulmonary granulomas caused by the Mycobacterium avium-intracellulare (MAI) complex. METHODS: We retrospectively analysed a series of 73 consecutive patients with solitary pulmonary granuloma and negative sputum smear and culture results, in whom the diagnosis was established by histological examination of specimens obtained by partial pulmonary resection or lobectomy. We compared the clinical features and HRCT findings of the solitary pulmonary granulomas definitively diagnosed to be caused by the MAI complex with those of granulomas of other causes by univariate and multivariate analyses. RESULTS: In this study series of 24 patients with solitary pulmonary granuloma, the aetiological agent was established as being the MAI complex. According to the results of the multivariate analysis, 'female sex', 'pleural indentation' and 'lobulation' on the HRCT images were significantly associated with solitary pulmonary granuloma caused by the MAI complex. CONCLUSION: This study demonstrated several characteristics of solitary pulmonary granulomas caused by the MAI complex, and suggested that it might be a subtype of pulmonary MAI complex infection without the typical radiographic features of the infection.