Meta-analyses of the association between Chlamydia psittaci and ocular adnexal lymphoma and the response of ocular adnexal lymphoma to antibiotics

BACKGROUND. There are conflicting reports regarding the association between Chlamydia psittaci (Cps) and ocular adnexal lymphoma (OAL) and the efficacy of antibiotics for OAL. In the current study, the authors attempted to clarify the association between Cps and OAL and the efficacy of antibiotics for OAL. METHODS. Two meta-analyses were conducted. One focused on the association between Cps and OAL across geographic regions and among different studies. The other was a meta-analysis of the response of OAL to antibiotic treatment. RESULTS. The authors identified 11 studies of Cps prevalence that included 458 cases of OAL from 10 different countries. Four studies regarding the efficacy of oral antibiotics to treat OAL were found. One hundred four of the 458 OAL specimens (23%) and 87 of the 346 mucosa-associated lymphoid tissue (MALT) lymphoma specimens (25%) were found to be positive for Cps. Ninety-four of the 104 Cps-positive OAL specimens (90%) came from 3 of the 11 studies. There was wide variation noted between geographic regions and even between studies from the same geographic region with regard to the rate of Cps positivity. The 4 studies concerning the efficacy of antibiotics for OAL were from Italy, Austria, Taiwan, and the U.S. and included 42 patients. Twenty patients (48%) achieved some response (complete response in 8 patients, partial response in 8 patients, and minimal response in 4 patients). Twenty patients also had stable disease, and 2 patients progressed during antibiotic therapy. Objective documentation of response (radiographs or clinical slit-lamp photographs) was available for only 3 of the 42 patients. Seven additional patients developed disease recurrence after their initial response or stable disease after antibiotic therapy; 6 of these cases of disease recurrence occurred during the first 12 months of follow-up. CONCLUSIONS. The findings of the current study suggest a striking variability in the association between Cps and OAL across geographic regions and even between studies from the same geographic regions. The overall rate of Cps positivity in our meta-analysis (23%) was much lower than that reported in the original report. The current study findings also suggest that antibiotics have variable efficacy against OAL. Future prospective trials with standard objective response criteria and a longer follow-up period would be necessary to evaluate the role of antibiotics in the treatment of OAL further.