[Idiopathic fibrosing alveolitis and bronchioloalveolar cancer].

A case of bronchiolo-alveolar carcinoma (BAC) developing in the presence of idiopathic fibrosing alveolitis (IFA) in a man of 67 with a long history of pulmonary lesion is described. A honeycomb bung was found at the autopsy. Histologically, multiple foci of BAC of mixed-cell structure and those of mucus-producing cells against the background of fibrosing alveolitis at the stage of honeycomb lung were observed. An increased content of collagen type III, IV and V was found immunohistochemically. The role of sclerotic changes and defected immunological surveillance over the epithelial regeneration in the IFA-affected lung in relevant carcinoma genesis is suggested. The origin of the lung carcinoma in IFA is considered to be the regenerating epithelium of the low respiratory tract.