[Inflammatory juvenile conjunctival nevus: a clinicopathological analysis of 19 cases]

Objective: The aim of this study was to analyze the clinical and histopathological characters of inflammatory juvenile conjunctival nevus (IJCN). Methods: Retrospective case series study. A total of 19 patients aged 18 years or younger with IJCN underwent conjunctival nevus excision surgery in Tianjin Eye Hospital from January 2015 to December 2023. The clinical signs (patient age, lesion location, and appearance, etc) as well as the hematoxylin-eosin staining and immunohistochemical staining appearances under an optical microscope were observed. Results: There were 10 males and 9 females. The age at surgery ranged from 5 to 18 years old, and the median age was 10 (6, 13) years old. All patients had a unilateral onset. The nevus was located at the temporal side of the bulbar conjunctiva in 13 eyes, at the nasal side in 5 eyes and at the inferior side in 1 eye. Nine lesions were adjacent to the limbus. The color of the lesions varied from yellowish-white to grayish-brown, with pigmentation in 15 eyes. The border was well circumscribed in 13 eyes. Follow-up data were available for 15 cases, with a median follow-up time of 51 (17, 54) months, ranging from 6 to 68 months, and no recurrence was found. Eighteen lesions were of the compound type, while one lesion was a junctional nevus. Lymphocytic and plasma cell infiltration was observed around the nevus cells. All nevus cells exhibited immunopositivity for S-100 and Melan-A proteins. HMB-45 was only positive within the superficial junctional zone, and the expression gradually decreased with the growth of nevus cells into the stroma. No nuclear PRAME expression was detected in any nevus cells. The ki-67 index ranged from 1% to 5%. The CK was positive in the conjunctival epithelium and epithelial inclusions (either solid or cystic). Cluster of differentiation (CD)20, CD3 and CD138 were expressed positively in inflammatory cells, which were mainly B cells in 13 eyes, plasma cells in 4 eyes, and T cells in 2 eyes. Conclusion: The IJCN primarily occurs in children and adolescents. It presents with a yellowish-white to grayish-brown flat mass on the bulbar conjunctiva. Most cases are compound nevi with prominent lymphocytic infiltration and conjunctival epithelial ingrowth between nevus cells.