Association between Chlamydia psittaci infection and extranodal marginal zone B-cell lymphoma of mucosa associated lymphoid tissue (MALT)-lymphomas

Abstract

7568 Background: MALT-lymphomas are often associated with infectious organisms. Microbial species associated with MALT lymphomas are: Helicobacter pylori (H.pylori), Campylobacter jejuni, Borrelia burgdorferi, and Hepatitis C Virus. Recent studies showed evidence of Chlamydia psittaci (C. psittaci) infection in 80% of ocular adnexal lymphoma and tumor regression following eradication therapy. We studied the presence of C. trachomatis, C. pneumoniae, and C. psittaci DNAs in MALT lymphomas of various sites and in non-malignant controls. Methods: MALT lymphomas from the following sites were selected for analysis: salivary gland (n=13), thyroid gland (n=4), skin (n=2), ocular adnexa (n=2), stomach (n=6), intestinum (n=4). Samples of Sjoegren syndrome (n=10) and samples of H. pylori positive gastritis (n=7) were included as non-malignant controls. Macrodissected tissue containing >80% lymphoma cells from paraffin embedded tissue was processed for DNA isolation. For the presence of C. psittaci and C. pneumoniae DNA real time PCR assays were used. For C. trachomatis a commercially available PCR assay (Roche Molecular Diagnostics) was employed. All samples were tested twice. A sample was regarded as positive if at least one positive result was obtained. Results: C. psittaci was found at variable frequencies in MALT lymphomas of different sites: 4/13 (31%) salivary gland, 2/4 (50%) thyroid gland, 2/2 (100%) skin, 2/2 (100%) ocular adnexa, 1/6 (17%) gastric, and 0/4 intestinal MALT lymphomas. Among the non-malignant specimens, C. psittaci DNA was detected in 4/10 (40%) samples of Sjoegren syndrome and in 0/7 samples of H. pylori positive gastritis. All nongastric MALT lymphomas tested were negative for C. trachomatis and C. pneumoniae. Conclusion: Our data reveal a clear association of C. psittaci infection with extragastric MALT lymphoma. However, no evidence could be established for C. trachomatis and C. pneumoniae infection. Moreover, the high prevalence of Sjoegren syndromes - the most frequent precursor lesion for MALT lymphomas of salivary gland and ocular adnexa - may suggest an involvement of C. psittaci induced antigenic driven lymphomagenesis in a significant proportion of extragastric MALT lymphomas. No significant financial relationships to disclose.