Morphology and morphogenesis of experimentally induced small intestinal tumors

Electron microscopic study of adenocarcinoma of the small bowel associated with Crohn's disease

"Crohn's Carcinoma" of a 34-year-old patient is presented in this paper. The fine structure of the tumour is discussed in detail, because there have been no previous reports of electron microscopic studies of this tumour. The adenocarcinoma cells were electron microscopically less differentiated than expected on the basis of light microscopic examinations. In the tumor cells, several round dense granules were observed. Similar granules were also described in the cells of intestinal type gastric and colon cancers, being considered a sign of pathologic mucus secretion. In a part of the tumour cells, intracisternal parallel tubular inclusions were seen like those described in malignant melanoma and osteosarcoma. In the dysplastic small-bowel mucosa adjacent to the tumour, the maturation disorder of the epithelial cells was similar to changes described in the precancerous states of the colon.

Grades of atypia in tubular and villous adenomas of the human colon. An electron microscopic study

Of a total of 544 tubular, villous and tubulo-villous adenomas of the human colon which were investigated by light microscopy, six tubular and six villous adenomas were examined under the electron microscope. It was shown that the two types of adenoma differ in their tissue architecture, but not in their cytological appearance. Different grades of epithelial atypia occur in both types of adenoma. These are designated as grades I to III, correspond to mild, moderate and severe atypia respectively. Whereas adenoma cells with atypia grade I clearly show a cytological relationship with crypt epithelia of the normal colonic mucosa under the electron microscope, adenoma cells with atypia grade III have largely lost the differentiation characteristics of the parent cells and there is no longer intracytoplasmic organization. In the cytoplasm of adenoma cells with atypia grade II, glycogen storage is found as a special feature which does not occur in normal colonic epithelium. A similar finding has been described in the course of malignant transformation of the liver and kidney and thus can be regarded as a further indication of the precancerous nature of the adenomas.