[Significance of the preferentially expressed antigen in melanoma in discriminating the conjunctival malignant melanoma and pigmented nevus].

<b>Objective:</b> To investigate the significance of the preferentially expressed antigen in melanoma (PRAME) in the differential diagnosis of the conjunctival malignant melanoma and pigmented nevus. <b>Methods:</b> Specimens from 86 patients with conjunctival malignant melanoma (42 males and 44 females, aged 18 to 84 years) and 86 patients with conjunctival pigmented nevus (47 males and 39 females, aged 1 to 82 years) were collected at Zhongshan Ophthalmic Center, Sun Yat-sen University from January 2017 to July 2024. Immunohistology was performed to detect the PRAME expression. The difference of PRAME expression in the two kinds of conjunctival melanocyte hyperplasia lesions and the correlation of PRAME expression with clinical stages of the conjunctival malignant melanoma (T1 to T4) were analyzed. <b>Results:</b> Most patients with malignant melanoma had a positive PRAME expression (89.53%, 77/86), while only 1 patient with pigmented nevus showed a positive PRAME expression (1.16%, 1/86). The positive expression rate of the PRAME in conjunctival malignant melanoma tissues was significantly higher than that in conjunctival pigmented nevi (<i>P</i><0.05). The PRAME had a sensitivity and specificity of 89.53% and 98.84%, respectively. The expression of the PRAME among patients with conjunctival malignant melanoma in different age groups (>50, 30 to 50, <30) was significantly different (<i>P</i><0.05). However, the PRAME expression had no difference in different clinical stages of the conjunctival malignant melanoma (<i>P</i>>0.05). <b>Conclusions:</b> The PRAME has significance in discriminating the conjunctival malignant melanoma and pigmented nevus. It is a useful biomarker in the diagnosis of conjunctival malignant melanoma.