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±15.5years. 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.