Roentgenographically occult bronchogenic carcinoma of non-polypoid type: histological patterns of longitudinal growth within the bronchus.

Microscopy of the serial block-sections of the entire bronchial tree of all the resected specimens of roentgenographically occult bronchogenic carcinoma revealed new findings with respect to the histological patterns of longitudinal growth within the bronchial wall. Twenty-seven lesions which were non-polypoid on gross appearance with longitudinal extension of 16 mm and above were classified into the following four categories. (A) In standard superficial extension, transmural invasion by carcinoma became shallower and the area involved on section became smaller gradually from the site of the origin of carcinoma to the proximal and distal ends. (B) In intraepithelial extension, carcinoma was confined within the epithelium throughout the bronchi involved except at and near the site of the origin at which it penetrated the basement membrane. (C) In lymphatic extension, carcinoma extended from the site of the origin to the proximal and distal ends in a dual pattern so that it extended longitudinally within the epithelium in parallel with an invasion into the lymphatic vessels in the lamina propria and submucosa. At the site of the origin carcinoma invaded down to the level of the submucosa or adventitia. (D) In massive extension, a massive invasion by carcinoma from the site of the origin to the proximal and distal ends, and a simultaneous invasion and destruction by carcinoma of the epithelium, basement membrane, lamina propria, submucosa, and of adventitia in places were demonstrated. There was no marked difference in bronchoscopic finding among (A), (B) and (C). The length of the lesion as estimated by histology was different from that observed at bronchoscopy. Bronchoscopic examination was not always successful in determining the line of resection precisely. Therefore it is indispensable to examine frozen sections and/or imprint specimens of the margin of resection.