Confusing Carbs!! – Carbohydrate staining simplified for review quiestion on the topic -click here for multiple choice questions- special stains- click here Carbohydrate staining is confusing isn’t it? Lets try and simplify it! (Staining procedures and methods will not be discussed, only the interpretation) PAS and Alcian blue staining will be discussed TABLE OF CONTENTS1. Types of carbohydrates2. PAS( Periodic acid Schiff) staining3. Alcian blue staining4. Combined PAS + Alcian blue staining5. Combined Alcian blue + High iron diamine staining6. SummaryTABLE OF CONTENTS 1.TYPES OF CARBOHYDRATES Group 1: Neural Polysaccharides or non-ionic homoglycans: This group has glucose containing glycogen, starch and cellulose as well as N-acetyl glucosamine containing chitin. Group 2: Acid mucopolysaccharides or anionic heteroglycans: Hyaluronic acid and Chondroitin sulfate belong to this group. Group 3: Neutral mucins, Carboxylated mucins (sialomucins) as well as sulfated mucins (sulfomucins) are present in this category. NEUTRAL MUCINS CARBOXYLATED MUCINS SULFATED MUCINS Surface epithelia of the stomachBrunner glands of the duodenumProstatic epithelium Bronchial submucous glandsGoblet cellsSalivary glands Bronchial mucus glands Group 3 Remember: Carboxylated mucins or sialomucins (also called simple mucins) are weak acids whereas sulfated mucins (also called complex mucins) are strong acids Group 4: Glycolipids and Phosphatides belong to this group. WHICH OF THESE GROUPS IS PAS (PERIODIC ACID SCHIFF) POSITIVE? Group 1 is always PAS positive Group 2 is always PAS negative. Group 3 and 4 is also PAS positive. Remember: Mesenchymal polysaccharides such as Hyaluronic acid and Connective tissues polysaccharides such as Chondroitin sulfate are always negative for PAS. Carbohydrate staining – Periodic acid-Schiff (PAS) stain -Positive gastric foveolar cells6. SUMMARY OF CARBOHYDRATE STAINING PAS Positive cell and tissue components 1.Glycogen2.Starch3.Mucins (Neutral mucins>sialomucins>sulfomucins)4. Basement membranes5. α-antitrypsin6.Reticulin7.Fungi (capsules)8.Pancreatic zymogen granules9.Thyroid colloid10.Corpora amylacea11. Russell bodies Carbohydrate staining- Periodic acid-Schiff (PAS) stain highlights the microvillous along the apical surface of the absorptive cells. Diseases in which PAS staining can be used for diagnosis Glycogen storage diseaseAdenocarcinomaPaget’s disease of the breastStaining macrophages in Whipple’s diseaseFungal infectionAlveolar soft part sarcomaErythroleukemiaα1-antitrypsin deficiencyEwing sarcomaPulmonary alveolar proteinosis 3. LET’S MOVE ON TO ALCIAN BLUE STAINING Group 1 is always Alcian blue negative Group 2 is always Alcian blue positive. Hyaluronic acid is positive at a pH of 2.5 and Chondroitin sulfate is positive at a pH of 0.5. Group 3 is the confusing part, we need to divide it into three parts for better understanding 1.Neutral mucins– Always alcian blue negative. 2. Sialomucins or carboxylated mucins– Alcian blue positive at a pH of 2.5 3. Sulfated mucins– Alcian blue positive at a pH of 1. Group 4 is Alcian blue negative. Alcian blue staining of Barrett mucosa at a pH of 2.5- Goblet cells are stained blue and gastric mucous cells are clear. Alcian blue stain is frequently combined with PAS and High iron diamine for diagnostic purposes (discussed below). Alcian blue staining of cartilage at pH 0.5 4. COMBINED PAS AND ALCIAN BLUE STAINING Primary use of PAS+Alcian blue combined staining is to distinguish neutral and acidic especially sialomucns. Diagnostic utility: 1. To distinguish eccentric gastro-esophageal junction from Barret’s mucosa 2. Gastric intestinal metaplasia Remember: Key finding an diagnostic feature intestinal metaplasia is the presence of goblet cells. Goblet cells and surface epithelial cells of stomach may be difficult to distinguish in routine Hematoxylin and Eosin stained sections. Goblet cells are positive with both PAS and Alcian blue but gastric epithelial cells are positive with PAS alone. When combined PAS+Alcian blue staining is performed, Goblet cells stain PURPLE and Gastric foveolar cells stain MAGENTA. Barrets esophagus showing goblet cells PAS + Alcian blue stain showing purple colored goblet cells and magenta colored gastric foveolar cells at pH 2.5. 5. COMBINED ALCIAN BLUE AND HIGH IRON DIAMINE Combined PAS + High iron diamine is used to distinguish between sulfomucins and sialomucins. Diagnostic utility: Large bowel metaplasia can be identified, since it contains both sulfomucins and sialomucins, in contrast to small bowel metaplasia (sialomucins only) With Alcian blue + High iron diamine staining- Sulfomucins: BROWN COLOR and Sialomucins: BLUE COLOR Sulfomucins stained brown with High iron diamine and few sialomucins stained blue. 6. SUMMARY OF CARBOHYDRATE STAINING PAS is always negative in mesenchymal and connective tissue mucopolysaccharidesAlcian blue is always negative in neutral mucinsPAS+Alcian blue is key to distinguish ectopic gastric mucosa or eccentric gastroesophageal junction from Barret’s mucosa in the esophagus. click here for the Review question Comment your queries and suggestions!! Thank you! Check this link for Key Points on Hematoxylin and eosin staining Liked the page? Why not leave a tip for it’s creators Share this:FacebookTelegramWhatsAppMoreLinkedInTwitterLike this:Like Loading...