Electron microscopic and biochemical studies on the bronchial carcinoid tumor

Abstract

cinoid tumor has been discussed in numerous theories. Postulated, among other theories, is that this tumor originates from onocytes,l7~ 38 bronchial buds,l3 bronchial Colinterparts of the intestinal argentaffin cell37 and bronchial 28 T h e latter of these assumed origins probably is accepted the most widely, particularly in view of the occasional observation of an apparent transition from normal gland to tumor28 and the frequently found distinct separation of bronchial surface epithelium from the underlying tumor.25 Further support was added to this assumption by the coincidence of the predominant localization of the tumor and the mucous glands2" although peripheral and multiple tumors have been reported.8 This theory of the origin of the carcinoid tumor from bronchial glands is contradicted by the nearly 2 dozen published case reports on benign and malignant carcinoid tumors of the lung in which the affected patients exhibited a carcinoid syndrome, supported in some instances by the presence of elevated levels of serotonin and/or its metabolites in the body fluids and the occasional observation of a bronchial carcinoid tumor containing argentaffin granuIes.35,39 These findings imply that the carcinoid form of bronchial tumor arises from a Kultschit7kytype (entero-chromaffin, argentaffin, argyrophil, basal clear or yellow) cell, a fact supported by the long recognized and obvious histological similarity between the intestinal and bronchial carcinoid tumors. Indeed, the