Follicular lymphoma of the ocular adnexa: Clinicopathological findings with flow cytometry analysis of eight cases.

Abstract

Flow cytometry (FCM) is used to evaluate cell surface markers of various leukocyte populations quantitatively. However, little is known about the usefulness of FCM in follicular lymphoma (FL) of the ocular adnexa. The aim of this study was to evaluate the clinicopathological features and FCM results in ocular adnexal FL. This is a retrospective multicenter case study on clinical and immunohistochemical features. All tumors, surgically excised, were diagnosed based on histopathology, immunoglobulin heavy chain gene rearrangement, and FCM. The percentages (%) of B-cell markers, T-cell markers, a natural killer cell marker, and cell surface kappa/lambda measured by FCM analysis in tumor tissues were searched based on medical records. This study enrolled nine tumors in eight FL patients (three men and five women). The median age at the time of initial presentation was 74 years. All the tumors surgically excised histologically exhibited cluster of differentiation (CD)10, CD20, and BCL2-positive cells. At the time of ophthalmic diagnosis, lymphomas were already disseminated throughout the body in five cases. FCM demonstrated high percentage of B-cell markers including CD10, CD19, CD20, and CD23 in all nine tumors. CD10 population was 73.5% ± 11.9% in seven out of nine tumors, while that in the other two tumors was particularly low being 11.7% ± 1.13%, which showed the relatively high T-cell lineages compared to the other seven tumors. For ophthalmologists involving managements of ocular adnexal tumors, FCM can provide useful information for complementing the diagnosis and understanding pathophysiology of FL.