Intestinal endoscopy, light and electron microscopy of the intestinal biopsy. Video-endoscopy of the jejunum of patient (A) shows the typical white coating (« white hoary frosting ») on the small intestinal mucosa, which is not observed in a normal subject. Light microscopy of the jejunal biopsy stained with hematoxylin/eosin (B) shows vacuolated enterocytes that stain positively with Oil Red O predominantly at the tips of the villi (C). Goblet cells are normal. Electron microscopy at low magnification of the biopsy shows large lipid droplets in the cytoplasm as well as smaller lipoprotein-sized particles (D).