Conjunctival /Corneal Intraepithelial Neoplasia: The designation conjunctival/corneal intraepithelial neoplasia (CIN) is now used for epibulbar squamous neoplasms. By definition, these lesions are localized to the epithelium and do not invade the epithelial basement membrane. They show a spectrum of malignant change at the cellular level, ranging from a benign appearance to severe dysplasia and anaplasia throughout the entire thickness of the epithelium. These lesions have a gelatinous, sessile appearance with numerous tiny superficial corkscrew like blood vessels typically located at the limbus (see next).

Conjunctival / Corneal Intraepithelial Neoplasia1: If CIN spreads onto the adjacent cornea, the corneal epithelium will typically have an irregular opalescent appearance with small, white, intraepithelial opacities and a central fimbriated edge. A white plaque protein, termed leukoplakia, may overlie a portion of the CIN. HPV strain 16 DNA sequences have been detected in many of these lesions. If and when invasion beneath the epithelial basement membrane (or distant metastasis) occurs, a true squamous cell carcinoma exists and the term CIN no longer applies. The dysplastic epithelium in CIN often stains with rose Bengal dye. If CIN is suspected, excisional biopsy is recommended. Adjunctive Cryotherapy to the conjunctival borders and bed of the excision has been reported to decrease the rate of recurrence from approximately 30% to less than 10%.

Conjunctival Lymphoma :Both benign reactive lymphoid hyperplasia and malignant lymphoma of the conjunctiva can produce a salmon-colored tumor. Benign reactive lymphoid hyperplasia is composed of a mixture of T and B lymphocytes. The B cells are polyclonal in that they produce more than one type of immunoglobulin. Conjunctival lymphomas are composed of a monoclonal B-Iymphoproliferation. Because benign and malignant conjunctival lymphoproliferations have a similar histopathologic appearance, immunohistochemical studies looking for a predominance of one type of immunoglobulin light chain, or Southern blot hybridization studies looking for immunoglobulin gene rearrangements, are often required to diagnose lymphoma. Because conjunctival lymphomas are occasionally associated with systemic lymphomas, systemic evaluation is recommended. Benign reactive lymphoid hyperplasia can respond to topical, periocular, or systemic corticosteroid therapy. Conjunctival lymphomas without systemic involvement may be treated with local low-dose irradiation. lymphomas with systemic involvement are most often treated with systemic chemotherapy. 

Primary Acquired Conjunctival Melanosis (PAM) :In this disease intraepithelial melanocytes proliferate to produce multiple flat, brown, intermittently changing patches of unilateral pigmentation within the superficial conjunctiva. The lesions are acquired, tend to occur in middle age, and are the equivalent of lentigo maligna of the skin. PAM is different from acquired racial melanosis (the perilimbal ring of benign pigmentation that occurs after birth in darkly pigmented individuals) and from secondary acquired melanosis caused by Addison's disease, radiation, pregnancy, or other causes. Although PAM can represent a benign proliferation of melanocytes in the ocular surface epithelium, these lesions have the potential for malignant transformation, and malignant melanoma develops in approximately 20% to 30% of cases. Melanomatous change should be suspected if pigmented nodules develop in previously flat lesions. The appearance of nodules is an indication for excisional biopsy. If excised lesions show histopathologic evidence of atypia or malignancy, cryotherapy to the margins of excision is recommended.