[Analysis of clinicopathologic characteristics of 422 conjunctival melanocytic nevi specimens]

Objective: To describe the clinicopathologic characteristics of 422 conjunctival melanocytic nevi and detect the incidence of malignancy in those patients. Methods: Retrospective case series study. A retrospective study was conducted by reviewing 422 conjunctival melanocytic nevi specimens obtained at Beijing Tongren Eye Center from June, 2004 to May, 2016. The data included the information of gender, age, clinical and histopathological diagnosis of all collected conjunctival melanocytic nevi cases. All patients were divided into three groups according to age: juvenile groups (<18 years old), young group (18-40 years old) and the elderly group (>40 years old). The histopathology change and its malignant incidence of conjunctival nevi in different age and sex were analyzed by SPSS 18.0 software package. Results: Of the 422 cases, 195 were males and 227 were females (male∶female=0.89∶1). The average age at surgery was (27.9±17.9) years old. The pathological types of conjunctival nevi included compound nevus, intraepithelial nevus and junctional nevus. The most common type of conjunctival nevus was compound nevus (256 cases, 60.7%; mean age (22.2±15.4) years old). The second was intraepithelial nevus (130 cases, 30.8%; mean age (37.7±16.6) years old). The least was junctional nevus (36 cases, 8.5%, mean age was (32.7±22.4) years old).The average age of patients with different types of conjunctival nevi was statistically significant (F=3.169, P=0.031). Occurrence of conjunctival compound nevus was most common in juvenile group (44.1%), followed by the young group (40.6%), and the elderly group (only 15.2%). Occurrence of conjunctival intraepithelial nevus was the most common in youth group (45.4%), followed by the elderly group (44.6%), and youth group was relatively rare (only 10%). The junctional nevus appeared mainly in elderly group (44.4%), but the junior group also had 13 cases (36.1%) and younger group had 7 cases (19.4%). Among 422 cases of conjunctival nevi, 37 cases transformed into malignant tumor. The canceration rate was 8.8%. The average age of malignant patients was (48.6±12.1) years old. Comparing with the patients without malignant, the age was age (25.3±4.2) years old and there was a significant difference (t=4.252, P=0.002). Among them, 24 cases (64.9%) came from conjunctival compound nevus and 13 cases (35.1%) came from the junctional nevus. Non malignant cases occurred in patients with conjunctival intradermal nevus. The male and female average age of patients with malignant transformation from compound nevus and junctional nevus were not statistically significant (P=0.730, 0.993). Thirteen cases were occurred malignant change in 36 cases of patients with junctional nevus, accounting for 36.1% of all patients with junctional nevus. It was obviously higher than the average malignant incidence of conjunctival nevi (8.8%). Non malignant junctional nevus were most common in juvenile group, and malignant junctional nevus were most common in the elderly group. Conclusions: The pathological type distribution of conjunctival melanocytic nevi in different age groups was different, and the onset age of different types of melanocytic nevi was also different. Patients with junctional nevus were prone to malignant change, and most of them were middle-aged and elderly patients. (Chin J Ophthalmol, 2017, 53: 583-587).