Lymphatic microvessel density as a predictive marker for the recurrence time of pterygium: A three-year follow-up study

PURPOSE To investigate whether lymphatic microvessel density (LMVD) could be used as a predictive marker for the recurrence time of pterygia. METHODS This was a prospective case series study. Ninety-six patients with unilateral eye primary nasal pterygia were included. The patients were clinically evaluated to grade the severity of their pterygia (32 were Grade 1, 29 were Grade 2, and 35 were Grade 3) before they underwent bare sclera resection with the use of mitomycin C. Excised tissues from the 96 patients and the ten normal nasal conjunctiva obtained from age-matched donor eyeballs (controls) were immunostained with LYVE-1 and CD31 monoclonal antibodies to evaluate LMVD and blood microvessel density (BMVD). The patients were followed up for three years or until pterygium recurrence was identified, which was defined as fibrovascular regrowth past the limbus in a previously compromised area. The recurrence time (RT) for a pterygium was calculated, and its relationship with LMVD and/or BMVD was statistically analyzed. RESULTS In total, there were 24 cases of pterygium recurrence. The recurrence rate of Grade 1 was 28.1% (9/32), Grade 2 was 24.1% (7/29), and Grade 3 was 22.9% (8/35), as classified in the primary pterygium (p>0.05); the overall recurrence rate was 25% (24/96) for all patients during the three-year follow-up. In the tissue analysis, there were a small number of CD31 (+), LYVE-1(-) BMVD and only a few CD31 (weak), LYVE-1(+) LMVD in the ten normal nasal conjunctiva tissues. BMVD and LMVD increased significantly in the pterygium tissue compared to the control tissue and were significantly correlated with the width and area of pterygium in Grades 1-3 (all p values <0.05). RT was not correlated with BMVD or pterygium grade, but LMVD was significantly and negatively correlated with RT within each group and in the total patient cohort. Furthermore, we determined that an LMVD greater than 20 in the surgical specimens predicted pterygium recurrence. CONCLUSIONS The LMVD of surgical specimens is an independent risk factor and a valuable predictive factor for the recurrence time of pterygia.