Periodic Acid-Schiff Staining with Diastase.

Periodic Acid-Schiff (PAS) with diastase (PAS-D) refers to the use of the PAS stain in combination with diastase, which is an enzyme that digests the glycogen. The purpose of using the PAS-D procedure is to differentiate glycogen from other PAS-positive elements in tissue samples. The PAS-D method is also used for periportal liver staining of AAT polymer inclusions that are seen in alpha-1 antitrypsin deficiency disease. Here, we describe the procedure of PAS-D staining in formalin-fixed, paraffin-embedded human liver tissues.