| Abstract: | Eight cases of papillary adenocarcinoma of the lung were investigated by light and electron microscopy. Prognoses for all but one patient were favorable. Two patients (husband and wife) who underwent tumor resection during the same year experienced no disease-related problems for more than seven years afterward. Microscopic study of the papillary adenocarcinomas revealed columnar, peg-shaped, mucus-secreting tumor cells lining the alveoli. The tumor tissue contained alveolar macrophages, with some multinucleated giant cells, interstitial lymphoid infiltrates, mildly thickened alveolar walls, and a few pneumoconiotic foci. These inflammatory stromal reactions in the tumor tissue might have been associated with the favorable prognoses. Nuclear inclusions were detected in some tumor cells in all cases. Ultrastructurally, the inclusions contained tubular, granular, crystalline, and electron-dense homogeneous structures in addition to unclassifiable nuclear bodies. The tubular structures were in close proximity to inner leaflets of the nuclear membranes. The papillary adenocarcinoma cells had features of totipotential bronchioloalveolar cells, differentiating toward type II pneumocytes, Clara cells, and ciliated epithelial cells. |
