"Ayoub-Shklar" as a Special Stain for Keratin: A Histopathological Study.

Background: Special stains in histopathological studies are used to identify the structures with different dyes apart from the routine stain hematoxylin and Eosin (H and E). The component which is present in the special stains will have a specific bond and affinity for particular tissue components in the histological specimen. Structures like keratin takes up an eosinophilic stain in routine (H and E) staining. Most of the potentially malignant disorders and carcinomas arise due to the keratinization defect, which makes keratin an important diagnostic tool. There are different stains such as Ayoub-Shklar (A-S), Dane-Herman (D-H), and rapid Papanicolaou (PAP) which is used to identify keratin. In A-S stain, keratins can be stained in magenta-red and orange colors.

Aim: we compared A-S special stain and routine stain in terms of staining intensity or quality, the pattern of staining, and specificity for staining keratin.

Materials and methods: Thirty cases from the department archives that included 10 well-differentiated squamous cell carcinoma, 10 verrucous carcinoma, and 10 epithelial dysplasia were taken and each case was stained with both A-S and H and E stain.

Results: A-S showed an almost equal distribution of uniform and patchy staining patterns, but H and E showed more patchy staining patterns in the three groups. H and E stain shows good staining quality than A-S. A-S shows almost 90% of satisfactory staining specificity.

Conclusion: Special stain like A-S stain can be used to stain keratin in different color, but H and E always remain gold standard stain.