Lack of Association between Chlamydophila psittaci and Ocular Adnexal MALT Lymphoma in Korean Patients—Is the Geographic or Genetic Difference Significant?

Clamydophila psittaci (C. psittaci) has been proposed to be an etiologic factor in extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) in the ocular adnexa. However, the pathogenetical significance of the infection has not been fully elucidated. Many previous studies have shown controversial results regarding C. psittaci detection rates in said patients, ranging from 0 to 87%. We investigated the presence of C. psittaci in a single institutional cohort (n = 150) of ocular adnexal MALT lymphoma (OAML) patients in Korea. We tried to exclude the methodological biases derived from the different primer sets in polymerase chain reaction-based studies. For that reason, we applied five sets of primers, including four previously reported and one newly designed primer set. There was no case of C. psittaci-positive OAML in repeated trials validated with appropriate positive and negative controls. All 150 cases showed negative results with five primer sets. These results suggest that the pathogenetic role of C. psittaci in ocular adnexal MALT lymphoma might have been overestimated to date, at least in the Korean population. Therefore, the molecular diagnosis of C. psittaci is considered a very low priority.