Extraocular muscle involvement in marginal zone B-cell lymphomas of the orbit.

Introduction: Marginal zone B-cell lymphoma is the most frequent ocular adnexal lymphoma. It may involve the conjunctiva, lacrimal gland, eyelid, extraocular muscle, and orbital connective tissue. Extraocular muscle infiltration is rare.

Methods: We report here a series of 5 patients presenting with extraocular muscle infiltration due to marginal zone B-cell lymphoma, extracted from a retrospective study of 39 patients with primitive ocular adnexal marginal zone B-cell lymphoma presenting within a 15-year period, from 1993 to 2007, at two university hospitals.

Results: Out of 39 patients, two females and three males presented with extraocular muscle involvement (one levator muscle, one medial rectus muscle, one lateral rectus muscle, one inferior rectus muscle, and one inferior oblique muscle). In 4 cases, the right eye was involved. The median age of presentation was 60 years. Proptosis and diplopia were the main clinical signs. A mean duration of symptoms was 12 months before diagnosis was given. Three patients were stage IE at the diagnosis, according to Ann Arbor classification, and one was at stage IV. Three patients received radiotherapy and two received chemotherapy. Three patients underwent local relapses at a median time of 40 months. The patients with relapses were treated with chemotherapy alone in one case, radiotherapy alone in one case, and immunotherapy and chemotherapy in one case. The mean follow-up period was 54 months.

Discussion: When compared to other locations of marginal zone B-cell lymphomas of the orbit, extraocular involvement occurred in younger patients and had similar prognosis.

Conclusion: Extraocular muscle involvement is a rare location of marginal zone B-cell lymphoma that had to be known and can simulate thyroid orbitopathy.