Perls’ test for iron (Prussian blue) has been performed on duodenal and jejunal specimens obtained by the Crosby capsule from healthy persons, as well as from patients affected with congenital hemochromatosis or acquired hemosiderosis (transfusion type). The small intestine was biopsied after an 18 hour fast.
As far as normal human beings are concerned, no hemosiderin was found in the epithelial cells of duodenum or jejunum, nor in the tunica propria of duodenum. On the other hand, the tunica propria of a number of jejunal villi showed siderotic macrophages which seemed to be storing or moving iron from the tips of the villi into the gut lumen.
In hemosiderosis, iron granulations were never found in the columnar epithelium, whereas siderotic macrophages, storing or removing iron, were much more numerous and iron-positive than in the normal, and these macrophages were not only in the tunica propria of jejunum, but also in that of the duodenum.
In hemochromatosis, the columnar epithelium of some duodenal villi had iron-containing granules, and many villi had siderotic macrophages in the tunica propria. These macrophages were not confined to the tips of villi, but were randomly distributed in the tunica propria. Furthermore, no macrophages appeared to be traversing the columnar epithelium or outside it.