Pathological and radiological changes in resected lung specimens in Mycobacterium avium intracellulare complex...

The present study was designed to evaluate the pathological and immunohistochemical findings of Mycobacterium avium intracellulare complex (MAC) lung infection. A retrospective study was performed in five cases with positive cultures for MAC in whom lung resections were performed between January 1989 and December 1996. A determination of whether or not MAC caused pulmonary disease was made using the 1997 criteria defined by the American Thoracic Society. In addition, MAC was cultured from all of the five lung specimens. Pathological and immunohistochemical findings as well as chest computed tomography (CT) findings were evaluated in these five patients. Pathological findings of bronchiectasis, bronchiolitis, centrilobular lesion, consolidation, cavity wall and nodules were demonstrated, respectively, in relation to chest CT findings. Extensive granuloma formation throughout the airways was clearly demonstrated. Immunohistochemical staining demonstrated: 1) epithelioid cells and giant cells; 2) myofibroblasts extensively infiltrating the cavity wall; and 3) B-cells detected in aggregates in the vicinity of the epithelioid granulomas. This study identified pathological and immunohistochemical characteristics of Mycobacterium avium complex infection relative to chest computed tomography findings and allowed the conclusion that bronchiectasis and bronchiolitis were definitely caused by Mycobacterium avium complex infection.