PAS diastase stain

PAS-D is a stain often used by pathologists as an ancillary study in making a histologic diagnosis on paraffin-embedded tissue specimens.

PAS stain typically gives a magenta color in the presence of glycogen.

When PAS and diastase are used together, a light pink color replaces the deep magenta.

In practice, the tissue is deparaffinized, the diastase incubates, and the PAS stain is applied.

[2] PAS diastase stain is also used in diagnosing Whipple’s disease, as the foamy macrophages that infiltrate the lamina propria of the small intestine in this disease possess PAS-positive, diastase-resistant inclusions.