Endocrine Cells In Nonendocrine Tumors Of The Gut And Pancreas

Endocrine tumors of the digestive tract and pancreas were recognized long before the presently available histochemical and immunohistochemical markers were available. Originally, these tumors were recognized by virtue of their histological characteristics, including the typical architecture (nodular, trabecular, or acinar arrangement of the cells) as well as the cytonuclear morphology (nuclear monomorphism, paucity of mitoses). Based upon these characteristics Oberndorfer 1 was one of the first to recognize the typical features of intestinal carcinoids and actually coined the term “carcinoid.” Subsequent to the recognition of the characteristic morphology of the tumor, it came to be regarded as a separate clinicopathological entity. Consequently, in the WHO classifications of tumors of the intestinal tract and pancreas, carcinoids are regarded as separate categories and are not included under the heading “malignant epithelial tumors.” In the gallbladder the WHO classification does not include carcinoid as a separate category. In the pancreas, tumors of the pancreatic islets are the equivalent of intestinal carcinoids. In the small and large intestine, as a subcategory of carcinoid the composite tumor has been recognized, which is defined as “a carcinoid tumour in which there is the general pattern of nonargentaffin carcinoid, but some of the cells have argentaffin properties and in other areas there are mucus-secreting acini.” In the appendix a comparable mixed neoplasm is headed under carcinoid tumors as goblet-cell carcinoid.