Pulmonary Mycobacterium avium complex disease showing nodular bronchiectasis--: pathological findings in two cases]

Histopathological examinations were carried out on 2 cases of Mycobacterium avium complex (MAC) disease of nodular bronchiectasis (NB) type on radiograms. The removed lung specimens revealed histological findings of granulomatous bronchiolopneumonia, consisting of epithelioid cell granulomas with lymphocytic infiltrations without exudation in the alveolar areas surrounding the respiratory bronchiole. The central bronchiolar walls were also affected by epithelioid cell granulomas with lymphocytic infiltration, occasionally showing polypoid protrusion into the bronchiolar lumen accompanying emphysema in the peripheral alveolar area. Bronchial lesions seemed to progress from peripheral to central airway with consequent atrophy and disappearance of intramural smooth muscles, resulted in bronchioloectasis. These histological findings well correspond to radiographical 'nodular bronchiectasis'. Large histiocytic granulomas without caseous necrosis developed in some area, which are not usually found in tuberculosis lesions. Epithelioid cell granulomas were occasionally found in the hilar lymph nodes as well as in the walls of lymphatic vessel in the pulmonary interlobular tissues, indicating intrapulmonary lymphatic spread of the mycobacteria.