Morphology and functional cytology of the small intestinal mucosa in malabsorptive disorders and other diseases.

Small intestinal biopsies from 98 patients have been studied macroscopically, histologically, and histochemically, and the results correlated with laboratory and clinical observations. Neither a convoluted nor a flat mucosa can be considered diagnostic for any specific disease. A flat mucosa was found in one adult with intestinal Hodgkin's disease and in another following total gastrectomy. Histochemically all specimens from subjects with coeliac disease and idiopathic steatorrhoea showed a deficiency of succinic dehydrogenase in the epithelial cells, and the histochemical test for this enzyme, although not specific, may be a useful aid to diagnosis, since the degree of deficiency in these diseases was usually grosser than that in any other conditions. Other but variable enzyme deficiencies that may be present in these two diseases showed no correlation with the reduction of succinic dehydrogenase activity, nor was there any correlation between reduced enzyme activities and the severity or otherwise of the clinical features.A number of specimens from patients with conditions other than coeliac disease and idiopathic steatorrhoea that had a normal macroscopic appearance showed some reduction of intracellular enzyme activities histochemically. This was not so in the control group, and if these deficiencies can be confirmed biochemically, then histochemical tests may give an earlier indication of disordered function than macroscopical or routine histological examination. At present neither the macroscopic appearance nor any single histological or histochemical test on the biopsy specimen is diagnostic for a particular disease. These findings must be considered with the clinical details and results of other investigations in establishing a diagnosis.