Conjunctival Melanoma Outcomes Based on Tumor Origin in 382 Consecutive Cases

Purpose: To evaluate prognostic factors based on origin of conjunctival melanoma. Design: Interventional case series. Participants: Three hundred eighty-two consecutive patients. Methods: Retrospective chart review. Main Outcome Measures: Melanoma-related metastasis and death. Results: The melanoma arose from primary acquired melanosis (PAM; n = 284; 74%), from pre-existing nevus (n = 26; 7%), and de novo (n = 72; 19%). The mean tumor base was 11 mm for melanoma arising from PAM, 6 mm for melanoma arising from nevus, and 10 mm for those arising de novo. At 5 years (10 years), melanoma metastasis occurred in 19% (25%) in melanoma arising from PAM (P = 0.003), 10% (26%) in melanoma from nevus (P = 0.193), and 35% (49%) in those de novo. Factors predictive of metastasis by multivariable analysis included tumor origin de novo (P = 0.001), palpebral location (P < 0.001), nodular tumor (P = 0.005), and orbital invasion (P = 0.022). At 5 years (10 years), melanoma-related death occurred in 5% (9%) in melanoma arising from PAM (P < 0.001), 0% (9%) in melanoma arising from nevus (P < 0.057), and 17% (35%) in those arising de novo. Factors predictive of death by multivariable analysis included tumor origin de novo (P < 0.001), fornix location (P = 0.04), and nodular tumor (P = 0.001). Conclusions: Melanoma arising de novo carries a higher risk of melanoma-related metastasis and death compared with those cases arising from PAM or nevus.