High frequency of squamous intraepithelial neoplasia in pterygium related to low ultraviolet light exposure

PURPOSE: The aim of this study was to determine the frequency of clinically unsuspected ocular surface squamous neoplasia (OSSN) in cases of biopsied pterygium (PT). METHODS: We reviewed 15,016 cases presented at the Henry C. Witelson Ocular Pathology Laboratory during the period 1993–2013. All cases with a clinical diagnosis of PT were included. Histopathological diagnoses were reviewed and demographic data were retrieved from histopathological request forms. All cases associated with OSSN were re-evaluated independently by two ocular pathologists. The classification of OSSN in PT cases was made based on the Armed Forces Institute of Pathology (AFIP) recommendations. RESULTS: Two hundred and fifteen cases were diagnosed clinically as PT (1.43%) and 54% were from male patients. The average age at diagnosis was 53.4 ± 15.5 years. OSSN was identified in five cases (2.33%), and four of these cases were from female patients (80%). The average age of patients with PT and OSSN was similar to PT patients without OSSN (P > 0.05). Cases with OSSN were diagnosed as conjunctival intraepithelial neoplasia (CIN) I (60%), CIN II (20%), and CIN III (20%). There was complete agreement between the two pathologists (100%). CONCLUSIONS: The relatively high rate of dysplasia in a low ultraviolet light index area challenges the main cause of this disease in our population, a hypothesis that should be evaluated in future studies. We suggest that all PT samples should be sent for histopathological evaluation even in areas with low ultraviolet light index.