LIGHT & ELECTRON MICROSCOPIC DESCRIPTIONS:
H&E sections from the native duodenum showed partial villous atrophy and an absence of the microvillous brush border (Figure 01), not well appreciated at this magnification.
PAS staining, which is nomally confined to the goblet cells and the brush border (Figure 02), highlights the absence of the intestinal brush border and diffuse staining of the apical enterocytes (Figures 03 and 04).
A normal intestinal alkaline phosphatase activity should be limited strictly to the brush border (Figure 05) but in the patient's biopsy there was intracytoplasmic and subapical positivity manifested as bright red inclusions.(Figure 06, arrow).
Electron microscopy showed the presence of intracytoplasmic inclusions within the surface enterocytes lined by brush border microvilli. (Figure 07, arrow, Orginal magnification: 3700x)and (Figure 08, Orginal magnification 18,500x ).