Hepatitis C virus in MALT-lymphoma of the ocular adnexa

Hepatitis C virus (HCV) has been proposed as a possible etiologic factor in ocular adnexal marginal zone lymphoma (OAML). We aimed to assess the prevalence of HCV infection in patients with OAML through a systematic review and meta-analysis. Electronic databases were searched from their inception to August 2019 for studies assessing HCV seroprevalence in patients with OAML. Pooled prevalence of HCV infection was calculated with 95 % confidence interval (CI). Statistical heterogeneity among studies was quantified via the inconsistency index (I2). Funnel plot symmetry was used to assess the risk of bias across studies. Nine studies with 360 patients were included. Overall pooled prevalence of HCV in OAML was 12.7 %, with low statistical heterogeneity (I2 = 17.4 %) and with asymmetrical funnel plot. The studies clustered into two groups: 5 studies (3 from Italy and 2 multicenter with a major Italian contribution) showed a higher HCV prevalence in OAML (15.6 %), while the other 4 (from countries other than Italy) showed a lower prevalence (4.7 %); in both subgroups, statistical heterogeneity was null (I2 = 0%) and funnel plot was symmetrical. HCV might be a significant etiologic factor of OAML in Italy.