Milman T, Eiger-Moscovich M, Henry RK, et al. - In this retrospective case series, researchers compared the sensitivity, specificity, accuracy, and inter-observer agreement of the two most commonly used classification systems for conjunctival melanocytic intraepithelial lesions with the new WHO classification. Pathology and medical records of all patients, who had a primary biopsy for conjunctival primary acquired melanosis (PAM) at Wills Eye Hospital between 1974 and 2002, with at least 36 months follow-up have been reviewed. Using three classification systems: PAM, conjunctival melanocytic intraepithelial neoplasia (C-MIN) and the WHO 4^th edition classification of conjunctival melanocytic intraepithelial lesions (CMIL), 12 ophthalmic pathologists analyzed scanned hematoxylin-and-eosin stained virtual microscopic slides. Sixty-four patients underwent 83 primary cryotherapy excisions for conjunctival PAM, with adequate tissue for histopathologic assessment. In terms of low-grade and high-grade lesions, the inter-observer percent agreement was 76% for PAM, 67% for C-MIN, and 81% for the WHO classification system. This research highlights the comparable strengths and shortcomings of the three classification systems for conjunctival melanocytic intraepithelial lesions and indicates that the simplified WHO classification scheme is ideal for the assessment of these lesions.