Conjunctival-corneal intraepithelial neoplasia: Presenting as a pterygium

Ocular surface squamous neoplasia (OSSN) comprises a wide spectrum of dysplastic alterations of the squamous epithelium of the surface of the eye, for example, the cornea and the conjunctiva ranging from "precancerous" lesions to bona fide invasive carcinoma. The epithelial infiltration can range from mild to severe dysplasia (i.e. mild, moderate, or severe corneal intraepithelial neoplasia) to full thickness epithelial dysplasia. We are presenting a case of a 55-year-old male patient who presented with a sudden increase in the size of her pterygium for the last 3 months, which were finally diagnosed to be carcinoma in situ.