Ocular adnexal lymphoma. What is the evidence for an infectious aetiology?

Ocular adnexal lymphoma is classified as non-Hodgkin’s lymphoma, the most common primary subtype of which is the low-grade extranodal marginal zone B-cell lymphoma of the MALT type (mucosa-associated lymphoid tissue).1 MALT lymphomas were first recognised in 1983;2 they occur in tissues normally devoid of lymph nodes such as the skin, gastric mucosa, lung, thyroid and salivary gland.3 The incidence increases with age and is highest among Asians and Pacific Islanders.4 Since 1975, the incidence of ocular NHL has increased approximately 6% per year, and ocular adnexal MALT lymphoma is increasing more rapidly than MALT lymphoma at other sites.4 It is possible that this may be related to a new infectious aetiology.

Many MALT lymphomas at non-ocular sites are associated with an infectious aetiology supporting the model of antigen-driven lymphomagenesis.3 An infection triggers chronic antigen stimulation of B cells and the production of antibodies; later, the proliferation of B cell clones becomes antigen-independent, and with uncontrolled proliferation, malignant transformation can occur.3 Borrelia burgdorferi and Campylobacter jejuni have been associated with marginal zone lymphoma of the skin and small intestine, respectively.5 6 However, the most frequently cited example is that of gastric MALT lymphoma where eradication of Helicobactor pylori, a cause of chronic gastritis, results in the resolution of early stage gastric MALT lymphoma.7 Interestingly, some extra-gastric, non-ocular MALT lymphomas have regressed following H pylori-eradicating antibiotic therapy.8 9 This finding led many to speculate that H pylori may have a role in ocular adnexal lymphoma. Although Ferreri and associates10 showed that H pylori antibiotic eradication was not effective treatment for ocular adnexal MALT lymphoma (OA MALT lymphoma), there is some published evidence for the role of H pylori in OAL. Chan et al …