Ocular MALT Lymphoma Free from the Chlamydia Psittaci Infection ; Analysis of 150 Cases

Background: Clamydophila psittaci (C. psittaci) has been proposed as an etiologic factor for extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) in the ocular region. However, previous studies showed varied association rates ranging 0% to 87%, not constant even in the series of same geographical areas, which suggest that there could be some technical variance in detecting methods for C. psittaci. The authors validated five sets of primers for detecting C. psittaci DNA and investigated its association with ocular MALT lymphomagenesis.

Material and Methods: Five sets of PCR primers including 4 previously reported and one newly designed were evaluated with positive control C. psittaci DNA (acquired from Korea Centers for Disease Control and Prevention). One hundred fifty cases of confirmed ocular MALT lymphomas were collected from pathology archives of our institutes from 2008 to 2014, and entered into this study. DNA was extracted from archival paraffin block sections with Qiagen DNA extraction kits. Quality of DNA was assessed with NanoDrop and beta-globin PCR. Standard PCR was performed together with negative (H2O and tonsil DNA) and positive control C. psittaci DNA.

Results: In all five primer sets for C. psittaci DNA, each PCR product showed clear positive band and negative with appropriate positive and negative controls, respectively. All 150 ocular MALT lymphoma cases showed positive for Beta-globin DNA control, but negative for C. psittaci DNA in any of PCR product with five primer sets.

Conclusion: These results suggest that possibility of the pathogenetic role of C. psittaci in ocular MALT lymphoma would have been overestimated so far, at least in Korean people.