Involucrin in laryngeal dysplasia. A marker for differentiation.

Involucrin is a major structural subunit of the cross-linked protein envelope that encases keratin in maturing squamous cells. Intracytoplasmic involucrin is identifiable via immunoperoxidase techniques as these cells migrate from the basal layer to the more superficial layers of the stratified epithelium. Normal squamous epithelia and mildly dysplastic epithelia show uniform staining in the suprabasal and superficial layers of the mucosa but show no staining in the basal layer. Moderate to severe dysplasias and invasive carcinomas demonstrate irregular or focal staining in all three layers. Thirty-three microscopic samples from 27 glottic laryngeal biopsy specimens were reviewed. The histochemically abnormal differentiation identified via involucrin staining correlated with accepted histologic criteria for dysplasia. Involucrin staining may provide objective information to assist the pathologist in differentiating degrees of dysplasia in laryngeal biopsy specimens.