Most ocular lymphomas are non-Hodgkin B-cell type, and less than 1% to 3% are T-cell type.2,14 Burkitt and Hodgkin lymphomas in the ocular adnexa are rare except in endemic regions.15 In this study, almost all the patients (96.1%) had B-cell NHLs, and only 5 (3.9%) had T-cell types. The major histopathologic subtype was MALT lymphoma (75.0%), followed by lymphoid hyperplasia (8.6%), diffuse large B-cell lymphoma (4.7%), and mantle cell lymphoma (3.1%). In this study of malignant lymphomas, 82.1% were MALT type, much higher than in Western countries, where the incidence is reported to be 35% to 70%.2,3,5- 8 However, according to previous studies in Asian populations, MALT lymphomas have a 79.5% to 91% incidence,2,3,5- 8 similar to what we found. In the West, follicular and lymphoplasmacytic lymphomas are relatively common, with an incidence of 11%to 53%2,3,16 and 4% to 24%,2,3,16 respectively. Only 1 patient was found to have lymphoplasmacytic lymphoma in the present study. In the West, diffuse large B-cell lymphomas represent approximately 7% to 15% of all ocular lymphomas, and they are the second most common lymphoma in the ocular adnexa.5,16- 19 In the present study of South Korean patients, diffuse large B-cell lymphomas represented 4.7% of all lymphoproliferative diseases and were the second most common lymphoma. These findings support the idea that racial differences affect lymphoma incidence, although the underlying cause of such differences is still unknown. Long-term antigen stimulation has been implicated as a causative agent in the development of some mature B-cell lymphoproliferative processes, as with Helicobacter pylori infection and MALT lymphoma of the stomach.20,21 Similarly, Borrelia burgdorferi and Campylobacter jejuni infections are associated with cutaneous marginal zone B-cell lymphoma and immunoproliferative disease, respectively.22,23 A possible association of Chlamydia psittaci with ocular MALT lymphoma has been reported. Ferreri et al24 detected C psittaci DNA in 80% of patients with ocular adnexal MALT lymphoma but in only 12% with reactive lymphoid hyperplasia. However, other studies25,26 of larger cohorts did not confirm this association. Recently, Chanudet et al27 suggested that there may be geographic variability in C psittaci distribution and that in different subtypes of ocular adnexal lymphoma, the bacterium seemed to be preferentially associated with MALT lymphoma. Infection with H pylori has not been widely associated with ocular adnexal lymphoma, although H pylori DNA was detected in tumor cells in 4 of 5 patients with conjunctival MALT lymphoma.28 Other studies29 have suggested that the presence of gastric H pylori did not affect clinical manifestation, even if they were common in patients with ocular adnexal lymphoma. Helicobacter pylori seropositivity has been reported in 45% of B-cell NHLs diagnosed in southern Switzerland, and it has been suggested that H pylori contributes to the pathogenesis of MALT lymphomas arising at different extranodal organs.30,31 As many as 90% of South Koreans are H pylori positive,32 much higher than in Western populations, where 43% of healthy individuals are H pylori positive.24,29,30 Thus, H pylori infection could be related to the higher prevalence of ocular adnexal lymphoma of MALT type in South Koreans. A study should be performed to elucidate the association of chronic H pylori infection with the differences in the incidence of ocular adnexal lymphomas in different populations.