Evaluation of the reactive T-cell infiltrate in uveitis and intraocular lymphoma with flow cytometry of vitreous fluid (an American Ophthalmological Society thesis).

Purpose: To describe the reactive T-cell infiltrate in uveitis and intraocular lymphoma using flow cytometry of clinical intraocular specimens acquired during diagnostic pars plana vitrectomy.

Methods: This was a retrospective review of diagnostic vitreous specimens (1992-2011) obtained at a university-based, tertiary care center. Seventy-eight patients with uveitis or lymphoma undergoing pars plana vitrectomy were selected for intraocular testing based on clinical diagnostic uncertainty. Pars plana vitrectomy with flow cytometry, gene rearrangement studies, and cytology was performed.

Results: T-cell infiltrates were found in all diagnostic categories with limited power to discriminate between uveitis and T-lymphocyte reactive infiltrates in response to intraocular lymphoma. Statistically significant differences by two-sample test of means between group means were found between 35 uveitis and 35 B-cell lymphoma cases for T-cell markers CD2, 3, 4, 5, and 7, but not for CD8. The CD4:CD8 ratio had a higher mean value in the uveitis group (P=.0113), and 8 T-cell lymphomas had a statistically greater number of CD3+ lymphocytes compared to uveitis (P=.0199) by two-sample test of means. Likelihood ratios were highest for CD2, CD5, CD7, CD4:CD8 ratio, CD20, and CD22.

Conclusions: Discrimination between uveitis and lymphoma based on cell identification by flow cytometry was limited because of the prevalence of T lymphocytes in all diagnostic categories, emphasizing the importance of a reactive T-cell infiltrate in B-cell lymphomas, which may impede diagnosis. Flow cytometry may allow identification of more cases of T-cell lymphoma than reported when it is combined with gene rearrangement and cytology.