Monoclonal antibodies in the diagnosis of lymphoproliferative diseases of the orbit and orbital adnexae

Aims To describe the value of monoclonal antibodies in the differential diagnosis of orbital lymphoproliferative disorders. Methods A total of 200 sequential cases of malignant lymphoma diagnosed at St Bartholomew's Hospital as part of the ocular lymphoma service at Moorfields Eye Hospital and the Institute of Ophthalmology have been examined. Cases were acquired between January 1998 and June 2005. Each case had detailed immunophenotypic analysis using a panel of monoclonal antibodies and was classified using the WHO classification of lymphoma. These cases are discussed in relation to earlier studies of orbital lymphoma reported by our group. Results Lymphomas fell into three main categories. Extranodal marginal zone lymphoma was the largest group with 151 cases, arising within the orbital soft tissue, conjunctiva and lacrimal gland. Cases arising in the conjunctiva and lacrimal gland showed a higher female predominance than those arising within the deeper soft tissue. A small number of cases were associated with organ specific autoimmunity, including thyroid eye disease complicating Graves' disease. Follicular lymphoma and diffuse large B-cell lymphoma formed the next two groups, occurring with equal frequency. Many of the follicular lymphomas had evidence of disseminated disease on completion of staging. A miscellaneous group of T-cell and B-cell lymphomas formed a minority of cases during the study period. Conclusion Extranodal marginal zone lymphoma is the most frequent type of primary orbital and orbital adnexal lymphoma. Its major differential diagnosis is with orbital lymphoid hyperplasia, chronic dacryoadenitis, and follicular conjunctivitis. Systemic types of lymphoma may present within the orbit or involve the orbit secondarily.