Periodic acid–Schiff stain

Periodic acid–Schiff (PAS) is a

.

• PAS diastase stain (PAS-D) is PAS stain used in combination with diastase, an enzyme that breaks down glycogen.

• Alcian blue/periodic acid–Schiff (AB/PAS or AB-PAS) uses alcian blue before the PAS step.

Uses

PAS staining is mainly used for staining structures containing a high proportion of carbohydrate macromolecules (glycogen, glycoprotein, proteoglycans), typically found in e.g. connective tissues, mucus, the glycocalyx, and basal laminae.

PAS staining can be used to assist in the diagnosis of several medical conditions:

• Glycogen storage disease (versus other storage disorders).
• Adenocarcinomas
  , which often secrete neutral mucins.
• Paget disease of the breast.^[1]
• Alveolar soft part sarcoma.^[2]
• Staining macrophages in Whipple's disease.^[3]
• It can be used to diagnose
  α1-antitrypsin deficiency
  if periportal liver hepatocytes stain positive.
• Aggregates of PAS-positive lymphocytes are present in epidermis in
  Sézary syndrome
  , called Pautrier microabscesses.
• Ewing sarcoma
• Erythroleukemia
  , a leukemia of immature red blood cells. These cells stain a bright fuchsia.
• Pulmonary alveolar proteinosis.
• Fungal infection, the cell walls of fungi stain magenta; this only works on living fungi.^{[citation needed]} In contrast, Grocott's methenamine silver stain (GMS) will stain both living and dead fungal organisms.
• It is used to identify glycogen in lung biopsy specimens of infants with pulmonary interstitial glycogenosis (PIG).
• It can be used to highlight super cross-linked lipids inclusions in ceroid lipofuscinosis (NCL).

Presence of glycogen can be confirmed on a section of tissue by using

to digest the glycogen from a section, then comparing a diastase digested PAS section with a normal PAS section. The diastase negative slide will show a magenta staining where glycogen is present within a section of tissue. The slide that has been treated with diastase will lack any positive PAS staining in those locations on the slide

PAS staining is also used for staining cellulose. One example would be looking for implanted medical devices composed of nonoxidized cellulose.

If the PAS stain will be performed on tissue, the recommended

See also

References

External links

• PAS Reaction