Comparison of modified Kreyberg's, modified Papanicolaou, Ayoub-Shklar, and Haematoxylin and Eosin stains to demonstrate keratin in paraffin embedded tissue sections

Keratin is an intermediate protein with a diameter of 7–11 nm which forms the cytoskeleton of all the epithelial cells. It forms the superficial most layer (stratum corneum) in keratinized epithelium in the oral cavity. Keratin may also be present in various pathologic conditions like squamous cell carcinoma, verrucous carcinoma and odonogenic keratocyst. The aim of the present study was to compare and evaluate the efficacy of staining of Ayoub-Shklar, Modified Papanicolaou, Routine Haematoxylin and Eosin and Modified Kreyberg's to stain known keratin tissue, and to obtain the best stain for keratin.

A total of 75 paraffin embedded tissue blocks were taken of known keratin containing tissue which included Well Differentiated Squamous Cell Carcinoma (WDSCC), Hyperkeratosis with or without dysplasia (HWD), Orthokeratinized Odontogenic Keratocyst (OKC) and Verrucous Carcinoma (VC). Four sections measuring 4 microns in thickness of each block were cut and were stained with all the mentioned stains.

Keratin was stained by all the four stains (Ayoub-Shklar, Modified Papanicolaou, Routine Haematoxylin and Eosin and Modified Kreyberg's) distinctly in WDSCC, HWD, OKC and VC. Ayoub-Schklar and Hematoxylin and Eosin stains showed better results, and was also statistically significant among all the stains for WDSCC, HWD, OKC and VC when intensity and patterns were compared.

It can be concluded that all the four stains (Ayoub-Shklar, Modified Papanicolaou, Routine Haematoxylin and Eosin and Modified Kreyberg's) can demonstrate keratin and based on the overall staining intensity and pattern. Ayoub-Shklar and H and E stains can be used efficiently to stain keratin but have certain limitations.