[Squamous neoplasia of the ocular surface in patients with pterygium in Peru].

OBJECTIVES To estimate the frequency of unsuspected ocular surface squamous neoplasia (OSSN) in pterygium, the accuracy of clinical diagnosis, and associated demographic and clinical characteristics. MATERIALS AND METHODS We reviewed histopathological reports of patients with a clinical diagnosis of pterygium and/or OSSN who were surgically treated between March 2009 and December 2012 at the National Eye Institute in Lima, Peru. The accuracy of the clinical diagnosis of OSSN was assessed by sensitivity, specificity, and likelihood ratios. Models of negative log-log regression were performed to identify demographic and clinical characteristics associated with increased odds of diagnosing OSSN. RESULTS 3,021 histopathological reports were reviewed. The frequency of unsuspected OSSN in pterygium was 0.65%. Clinical diagnosis had a sensitivity of 85%, a specificity of 99%, a positive likelihood ratio of 111.89, and a negative likelihood ratio of 0.15. Associated characteristics were male gender (OR =1.15; 95% CI: 1.01 to 1.30), age group of 61-80 years (OR = 1.54, 95% CI: 1.28 to 1.85) ≥ 81 years (OR = 3.10; 95% CI: 2.09 to 4.58), presence of recurrent lesions (OR = 1.59; 95% CI: 1.03 to 2.46) and temporal location lesions (OR = 3.57; 95% CI: 2.63 to 4.85). These characteristics were associated with a greater likelihood of OSSN. CONCLUSIONS A low frequency of unsuspected OSSN was found; however, it is recommended to routinely perform histopathology studies to avoid misdiagnosis of OSSN as pterygium.