Test Details: Periodic acid–Schiff (PAS) is a staining method used to detect polysaccharides such as glycogen and mucosubstances such as glycoproteins, glycolipids and mucins in tissues. It is mainly used for staining structures with a high proportion of carbohydrate macromolecules typically found in e.g. connective tissues, mucus, the glycocalyx, and basal laminae. It can be used commonly to assist in the diagnosis of several medical condition like Glycogen storage disease, Paget disease of the breast, Alveolar soft part sarcoma, Whipple's disease ,α1-antitrypsin deficiency ,Fungal infection etc. It can detect glycogen granules which may also be visible in tumours of the bladder, kidney, ovary, pancreas, and lung.