Pathologic analysis of carcinoids Histologic re evaluation of 62 cases

Sixty‐two carcinoids originating from varying sites of primitive gut including bronchus were collected, recut, stained with several special stains including argyrophil and argentaffin reactions, and reevaluated from the practical morphological point of view. Morphologically, these carcinoids were classified into A, B, C, D and mixed types. Such a new classification proved to correlate well with the original sites of these tumors. Further classification due to silver impregnations consisted of argyrophil, argentaffin, and non‐reactive types and indicated a certain correlation with tht sites of tumor development as well. Thus, the foregut‐derived carcinoids were predominant in B type and in argyrophil or non‐reactive types, the midgut‐derived carcinoids in A type and in argentaffin type, and the hindgut‐derived carcinoids in mixed type and in non‐reactive type. The results of the present observation have brought about a certain suggestion as to the pathogenetical difference between carcinoids depending upon the embryonic derivations.