Todayโs special stain is ๐๐๐!
๐๐ก๐๐ญ ๐ข๐ฌ ๐ ๐๐๐ ๐ฌ๐ญ๐๐ข๐ง?
PAS stands for ๐ฉ๐๐ซ๐ข๐จ๐๐ข๐ ๐๐๐ข๐-๐๐๐ก๐ข๐๐, and is a very common special stain used in pathology. It actually stains several things, so can be used for a lot of different purposes! One of the main reasons a pathologist might order a PAS is to highlight ๐๐๐ฌ๐๐ฆ๐๐ง๐ญ ๐ฆ๐๐ฆ๐๐ซ๐๐ง๐๐ฌ, which are thin layers of connective tissue that support ๐๐ฉ๐ข๐ญ๐ก๐๐ฅ๐ข๐๐ฅ ๐๐๐ฅ๐ฅ๐ฌ (cells that line surfaces). PAS also highlights ๐ฆ๐ฎ๐๐ข๐ง๐ฌ, which are proteins found in mucous produced by epithelial cells. This can be helpful if you suspect a tumour may have originated from a population of epithelial cells. Finally, it can also highlight some fungi.
This image is a case of ๐ฉ๐ฎ๐ฅ๐ฆ๐จ๐ง๐๐ซ๐ฒ ๐๐๐๐ง๐จ๐๐๐ซ๐๐ข๐ง๐จ๐ฆ๐ in a cat. Pulmonary adenocarcinoma is a malignant tumour that arises from the epithelium lining the lungs. These epithelial cells produce lots of mucous to help keep lung function running smoothly. In this tumour, you can see that several of the cells contain large sacs of pink-stained material. Thatโs mucin, highlighted by the PAS stain!
