Abstract Purpose: Ocular adnexal lymphomas (OALs) are rare, distinct subgroup of lymphomas constituting about 1-2% of all non-Hodgkins lymphomas (NHL) and approximately 8-20% of extranodal lymphomas. Most commonly it affects the lacrimal gland, lids, orbit and conjunctiva. It is reported that OALs may be an antigen driven disorder, however, the source of antigen(s) is not understood. Varying reports from different countries are available which suggests the role of Chlamydophila psittaci (Cp) in development and maintenance of ocular adnexal marginal zone B-cell lymphoma (OAMZL). The present study was undertaken to detect the presence of Chlamydia infection in patients with ocular adnexal lymphomas in Indian scenario. Materials and Methods: Prospective analysis of 41 OAL cases and 21 controls was performed. Diagnosis of Non-Hodgkin's lymphoma was confirmed by clinicopathological features and Hematoxylin & Eosin stained sections of FFPE tumors. WHO formulation of NHL (2001) was used for histopathological classification. Immunohistochemistry (IHC) was done on FFPE tumors using CD20, CD3, CD5, CD10, Cyclin-D1 and anti Chlamydia antibodies. Chlamydia antigen detection was performed on 27/41 OAL cases by indirect immunofluorescence (IFS), using monoclonal anti Chlamydia antibody. Nested PCR (n-PCR) was used to detect Chlamydia gene expression using genus specific primers and the products were sequenced & analyzed using NCBI Blast Software. Patients were followed up for 7-45 months (Mean follow up 26.6 months ± 12.1). Results: Of the forty one cases, thirty two cases (78%) were diagnosed as MALT lymphomas, six (15%) were diffuse large B-cell lymphomas (DLBCL) and three (7%) were mantle cell type lymphomas. The mean age of patients was 54.6 ±14.9 years with male preponderance. Chlamydia gene was detected by nested PCR in 3/41 (7%) cases, out of which, two were MALT lymphomas & one was mantle cell lymphoma. Sequencing showed all the three cases were positive for Chlamydia trachomatis. All the 3 PCR positive cases were also positive for IFS and only one case was positive by IHC for Chlamydia. The tumor was located in the orbit in two cases and eyelid in one case. Follow-up data revealed, systemic spread in two cases with bone marrow involvement (Stage T3N3M1b). All the 3 cases were subjected to 4-6 cycles of chemotherapy along with involved field radiotherapy and relapse occurred in 2 cases. Conclusion: Our study has shown association of C.trachomatis in 7% (3/41) OAL cases instead of C.psittaci infection, as reported in different geographic regions. However, this study has opened a new vista for further research on Chlamydia infection in OAL in this region (India) also. Note: This abstract was not presented at the meeting. Citation Format: Mansi Bhardwaj, Anjana Sharma, Seema Sen, Gita Satpathy, Neelam Pushker, Seema Kashyap, Lalit Kumar. Ocular adnexal lymphomas and chlamydia association: an Indian scenario. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1293. doi:10.1158/1538-7445.AM2015-1293