Diagnostic Accuracy of Vitreous Cytology in Patients with Vitreoretinal Lymphoma

(1) Background: To determine the diagnostic value of vitreous cytology in patients with vitreoretinal lymphoma (VRL) and evaluate its diagnostic accuracy relative to that of other diagnostic tests. (2) Methods: In total, 38 eyes from 38 patients with VRL who underwent diagnostic vitrectomy and were followed up for at least 6 months were analyzed. The clinical manifestations and VRL diagnostic rates for all diagnostic tests were determined. (3) Results: The presence of vitreous cells/opacity was the most common ophthalmic finding (97.4%), followed by sub-retinal pigment epithelial infiltration (65.8%) and retinal hemorrhage (21.1%). The VRL diagnostic rates were 89.3% for interleukin (IL)-10 levels > 50 pg/mL; 82.1% for IL-10/IL-6 ratios > 1; 60.0% and 63.3% for immunoglobulin heavy chain and kappa light chain clonality assays, respectively; and 44.4% for vitreous cytology. The VRL diagnostic rate for vitreous cytology was significantly lower in the steroid pretreatment group than in the non-steroid pretreatment group (p = 0.007). (4) Conclusions: The VRL detection rate for vitreous cytology was lower than that for the other tests, especially in patients who received steroid pretreatment. These findings suggest that even if vitreous cytology findings are negative, other tests and characteristic fundus findings should be evaluated to confirm VRL diagnosis.