Incidence of ocular surface squamous neoplasia in pterygium specimens

Objective: Pterygium and ocular surface squamous neoplasia (OSSN) have been recognized as likely related conditions and share similar risk factors such as ultraviolet radiation and chronic inflammation. The purpose of this study is to review the incidence of OSSN in pathology specimens sent as pterygium at a single tertiary centre between 2010 and 2022. Methods: This is a retrospective chart review of patients operated on for pterygium between 2010 and 2022 at the University of Montreal Health Centre. Data collected include baseline demographics, results of pathology specimen, and clinical information for cases diagnosed as OSSN on pathology. Results: A total of 1559 patients were operated on for a clinical diagnosis of pterygium between 2010 and 2022, of which 854 patients (55%) were male. A total of 1142 specimens had available pathology reports, and most of the specimens were consistent with pterygium on pathology (1105 of 1142; 97%). There was an unexpected finding of 3 cases of OSSN (3 of 1142; 0.3%). Other diagnosis besides pterygium were seen in 3% of specimens (34 of 1142), including nevus (n = 12), spheroidal degeneration (n = 3), pyogenic granuloma (n = 3), and lymphangiectasia (n = 2). The 3 cases of OSSN included an 81 -year -old male of French-Canadian background, a 52 -year -old male of South Asian background, and a 59 -year -old female of French-Canadian background. The pathology was diagnosed as conjunctival intraepithelial neoplasia (CIN) grade 3, CIN grade 2, and CIN grade 2, respectively. Conclusion: The finding of OSSN in pterygium is rare in our population but can be clinically difficult to distinguish. It is important to send all pterygium specimens for pathology.