Expression of involucrin by ocular surface epithelia of patients with benign and malignant disorders

Purpose. Keratinization of the ocular surface epithelium is associated with various disorders impairing vision. We immunohistochemically determined wh ether the ocular surface epithelia express involucrin, and whether its expr ession pattern may differ in benign vs. malignant disorders. Expression of cytokeratins was also examined to provide further information relative to t he epithelial differentiation. Methods. We evaluated 17 specimens; 6 specimens of the normal ocular surfac e epithelia, 3 specimens from cases of conjunctival intraepithelial neoplas ia (CIN), 6 of conjunctival squamous cell carcinoma (SCC) and 2 of conjunct ivae from cases of superior limbic keratoconjunctivitis (SLK). Results. Corneal epithelium exhibited intracellular immunoreactivity for in volucrin. Four of the 6 specimens of bulbar conjunctival epithelium showed involucrin immunoreactivity in the perimembranous region, whereas the forni cal conjunctiva was negative. Cornified envelope in SLK specimens was posit ive for involucrin. The CIN showed its immunoreactivity in the perimembrano us region in all levels of the hyperproliferative epithelium without kerati nization, i.e., similar to the bulbar conjunctiva. The neoplastic cells of well-differentiated SCC showed involucrin in the perimembranous region, and those of moderately- to poorly-differentiated SCC have involucrin in their cytoplasm. The expression pattern of cytokeratins was unrelated to grade o f malignancy in ocular SCC. Conclusion. The epithelia of normal subjects and of CIN expresses involucri n without keratinization. In contrary, the keratinized SLK epithelium marke dly expresses involucrin in the cornified envelope. The subcellular immunol ocalization of involucrin in the ocular SCC may help in evaluating the diff erentiation, i.e., malignancy, of neoplastic cells.