Correlation study of benign cytomorphology and final clinical diagnosis

Objective: To assess significance of cytologically benign vitreous samples and identify cellular patterns that may correspond to specific clinical entities. Study Design: Vitreous fluids with "negative for malignancy" cytologic diagnosis were identified from pathology department records, cytologic slides reviewed and clinical and follow-up information obtained. Results: Fifty-four cytologically benign samples were identified (1994-2004). The main indication for vitrectomy was confirmation of intraocular inflammatory process. Malignant process was included in the differential diagnoses of most samples. Macrophages or lymphocytes were the predominant cell types in 76% of cases. Most cases with macrophage or lymphocyte predominance were diagnosed as chronic uveitis or vitritis of unknown etiology. Infectious agents were identified in 7 cases with macrophage or lymphocyte predominance, 2 with abundant neutrophils and 1 with eosinophils. One had a diagnosis of malignant lymphoma, based on vitreous fluid from the opposite eye at another hospital. Three cases had blood only and 1 had lens fragments, both consistent with the diagnosis. Conclusion: Most cytologic features of benign vitreous fluids did not correspond to specific clinical entities. Abundant eosinophils suggested parasitic infection; the almost exclusive presence of blood indicated hemorrhage. Based on our study, negative predictive value of a benign vitreous sample is 98%.