Cost-Effective Staining Alternatives to Immunohistochemistry for Keratin Demonstration in Oral Epithelial Pathologies

A BSTRACT Background: Demonstrating keratin is crucial in diagnosing various epithelial pathologies and is typically done through histological and immunohistochemical (IHC) methods. While IHC staining for keratin is highly specific, it can be costly and time-consuming. Therefore, common histological staining methods for keratin, suitable for routine histotechniques labs, are gaining importance. Methodology: Twenty formalin-fixed, paraffin-embedded tissue blocks, each representing histologically confirmed normal oral mucosa (NOM), hyperorthokeratosis (HOK), and well-differentiated squamous cell carcinoma (WDSCC), were retrieved. Five histological sections of 4-μ thickness from each block were stained using routine hematoxylin and eosin (H and E), modified pap stain (mPap), Ayoub-Shklar (AS), Dane-Herman (DH), and Alcian blue-PAS stains (AB-PAS). Two independent observers evaluated the stained sections and scored staining specificity and intensity. Statistical comparisons were made. Results: All sections of NOM, HOK, and WDSCC showed positive staining for keratin with each of the five stains used. The staining specificity and intensity scores were highest with the AS stain and lowest with the AB-PAS stain. Conclusion: Routine H and E, mPap, AS, and DH stains effectively stained keratin with adequate intensity in NOM, HOK, and WDSCC. However, while AB-PAS stain also positively stained keratin, its staining intensity was poor across all three tissue types.