Diagnosis of intraocular lymphoma by flow cytometry

To evaluate flow cytometry of vitreous cellular specimens as a means of diagnosing intraocular lymphoma and ocular inflammatory disease.

We undertook a retrospective, observational study of hematopoietic cell-surface markers in 20 patients with vitreous cellular infiltration in whom lymphoma was considered in the differential diagnosis. Immunophenotyping of vitreous cells obtained by vitrectomy was performed by flow cytometry using antibodies directed against specific cell-surface antigens, including ones associated with B-lymphocyte and T-lymphocyte lymphomas and activated inflammatory cells. Smears were examined cytologically. Cytofluorography was compared with the cytopathologic diagnosis and with final diagnosis.

With flow cytometry, a diagnosis of intraocular lymphoma was confirmed in two of four patients with known lymphoma, one of whom had recurrent disease after radiation, and not confirmed in two patients who had had prior treatment with radiation or corticosteroids. In six patients with no prior diagnosis of lymphoma, five were diagnosed with lymphoma on the basis of cytofluorography. Thus, seven (70%) of 10 patients with intraocular lymphoma were diagnosed by cytofluorography compared with three (30%) of 10 with lymphoma diagnosed by cytology. With flow cytometry, 10 patients with uveitis or intraocular infections were distinguishable from patients with lymphoma by lack of a monotypic population and, in some cases, by elevated CD4:CD8 ratios and a high percentage of activated cells.

Cytofluorography of vitreous cells is an effective alternative or adjunct to cytology. Information can be gained from specimens that are uninterpretable by routine cytology. The optimal technique for diagnosis may vary among institutions.