Criteria for the Histologic Diagnosis of Bronchogenic Carcinoma

Abstract

SUMMARY 1.Cumulative reports have established that bronchogenic carcinoma may be simulated, histologically, by bronchial, lung and lymph node metastases from extrathoracic carcinomas. 2.A necropsy study of 124 cases of bronchogenic carcinoma and 224 cases of metastatic lung cancer revealed that histologic differentiation was not always feasible. 3.The definitive criteria for the diagnosis of squamous cell and oat-cell carcinoma consisted of (a) demonstration of the site of epithelial origin and (b) exclusion of features indigenous to metastatic tumors. 4.The histologic resemblance of peripheral metastases to adenocarcinoma precluded a positive diagnosis of primary lung cancer without necropsy. 5.The characteristic features of metastatic bronchial carcinoma in the early stages were involvement of the subepithelial lymphatics and preservation of the epithelium. 6.Pulmonary metastases from extrathoracic ductal or glandular carcinomas often presented as squamoid tumors containing few identifiable ductal structures. 7.Pulmonary metastases from extrathoracic squamous cell carcinomas usually showed a higher degree of keratinization and pearl formation than the primary squamous cell carcinomas of the lung. 8.A definitive clue to the diagnosis of metastatic tumors was the presence of cells typifying the site of origin. 9.The presence of carcinomatous emboli in the small arteries occurred predominantly in the cases of metastatic lung cancer. 10.Lymph node invasion presented problems in differential diagnosis because of the pleomorphic features of extrathoracic metastases and the simulation of oat-cell carcinoma by lymphosarcoma.