Immunocytochemical detection of involucrin in precancerous and cancerous non-pigmented conjunctival tumors

Abstract

Involucrin is a precursor of the cross-linked envelope protein of the human stratum corneum. Its appearance in the upper layers of the epidermis reflects normal differentiation of keratinocytes. This study uses an immunoperoxidase technique for localization of involucrin in paraffin sections of normal conjunctiva, conjunctival dysplasia, carcinoma in situ, and invasive carcinoma. Clinicoimmunocytochemical correlations are presented. The results demonstrate that the distribution patterns of involucrin differ in precancerous and cancerous conjunctival lesions: normal limbal conjunctiva shows involucrin only in the three superficial cell layers; the fornix conjunctivae contains no involucrin. All 23 conjunctival dysplasias show an involvement also of deeper layers of the epithelium, sparing the basal layers. Three carcinomas in situ and one invasive squamous cell carcinoma, however, demonstrate an involvement of all layers of the epithelium. The involucrin staining pattern helps in histologic differential diagnosis of epithelial lesions of the conjunctiva.