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- 31 y.o. female
with a malabsorption syndrome. Duodenal mucosa is pale looking
in endoscopy, with a mosaic pattern. Endoscopic biopsy ...
- Scanning view: Duodenal
villous pattern preserved.
- Low power view,
villi and crypts are regular.
- Tip of villi, are
lined by a columnar epithelium, having a clear cytoplasm.
- High power view,
enterocytes are stuffed with clear vacuoles.
- Closer view of the
- The epithelium gradually
becomes normal towards the crypts.
- Closer view on the
previous field: clear cytoplasmic vacuoles, are negative to special
stains in the processed tissues.
lesions with preserved intestinal villous architecture consistent
- is a rare group
of inherited disorders of childhood characterized by an absence
or a deficiency of apoprotein B, which is required to synthesize
and transport very low density lipoproteins and chylomicrons.
This results in normal absorptive cell uptake of fatty acids but
inability to synthesize them into chylomicrons. The absorptive
cells become stuffed with fat . Ultimately, fat is unable to enter
the absorptive cells and steatorrhea ensues.
- The mechanism of
chylomicron formation and secretion in the gut is complex. Following
lipolysis of dietary fat in the gut lumen, there is passive diffusion
of fatty acids into the endoplasmic reticulum of enterocytes.
Here chylomicron assembly occurs in the presence of phospholipids,
cholesterol, and a number of apoproteins. The chylomicrons are
then assembled in the Golgi apparatus and extruded by exocytosis
into the intercellular spaces or intestinal lymphatics. To date,
abnormalities have been described in apoprotein production and
from a defect in the final assembly of chylomicrons in the mechanism
- The small bowel
mucosa has a characteristic appearance. The upper two-thirds of
the villi contain epithelial cells that appear vacuolated and
- There is one case
report of a patient with a generalized neutral lipid disorder
in whom there were jejunal changes similar to abetalipoproteinemia.
However, this patient also had lipid accumulation in other parts
of the gastrointestinal tract, such as the gastric glands, and
in many other tissues, such as liver, striated muscle, and granulocytes.
- Another potential
source of diagnostic confusion arises when an infant with suspected
abetalipoproteinemia has a biopsy taken shortly after feeding.
In the postfeeding state with a meal containing fat, vacuoles
of absorbed fat may normally be seen in villous tip epithelium.
This confusion can usually be resolved easily by taking an appropriate
history and by avoiding feeding the infant for at least 6 hours
prior to biopsy. Vacuolar change is also found in severe mucosal
lesions, for example, celiac sprue. In these cases, the morphologic
features of a severe mucosal lesion are clearly seen and should
not pose any diagnostic problem.
- The other manifestations
of this disorder are retinitis pigmentosa, acanthocytosis
of red blood cells, ataxia, and mental retardation. Acanthocytosis
noted in smear of the peripheral blood.
- Variation in size
and form of RBC in the vessels noted in the duodenal biopsy (left)
are due to fixative agents, are also observed in biopsies without
acanthocytosis (right, Giemsa stain)