Purpose To report a case of recurrent therapy-resistant posterior scleritis in a patient with seronegative rheumatoid arthritis (RA). Following treatment with a tumor necrosis factor inhibitor (TNFi), an orbital lymphoma masquerading as a recurrence of posterior scleritis occurred. Methods Retrospective chart review. Results A 62-year-old woman was diagnosed with a unilateral posterior scleritis in 2008. Ophthalmological workup, including orbital imaging, confirmed the diagnosis. Complete systemic workup revealed a seronegative RA. Due to limited responsiveness to corticosteroids and conventional immunosuppressive therapy, adalimumab, a TNFi, was successfully initiated. Despite a recurrence-free period of 27 months, a relapse of posterior scleritis occurred. Systemic evaluation and orbital imaging showed a small orbital mass. Orbital biopsy confirmed the diagnosis of an extranodal marginal zone lymphoma or MALT. Conclusions Adalimumab is effective as a second-line anti-inflammatory drug in posterior scleritis. Studying the link between lymphoma and RA, several reports confirm an increased risk of lymphomas in RA with high disease activity. Although TNFi increases the risk of melanoma, there appears to be no increased risk of lymphoma. Whether it may be related to the underlying disease rather than to the treatment, ophthalmologists should be aware of the risk of a lymphoma.