Orbital Lymphoma-An International Multicenter Retrospective Study.

PURPOSE: To investigate and characterize the clinical features of subtype-specific orbital lymphoma. DESIGN: Retrospective, interventional case series. METHODS: The study included 7 international eye cancer centers. Patient data were collected from January 1, 1980 through December 31, 2017. A total of 797 patients with a histologically verified orbital lymphoma were included. The primary endpoints were overall survival, disease-specific survival, and progression-free survival. RESULTS: The median age was 64 years, and 51% of patients (n = 407) were male. The majority of lymphomas were of B-cell origin (98%, n = 779). Extranodal marginal zone B-cell lymphoma (EMZL) was the most frequent subtype (57%, n = 452), followed by diffuse large B-cell lymphoma (DLBCL) (15%, n = 118), follicular lymphoma (FL) (11%, n = 91), and mantle cell lymphoma (MCL) (8%, n = 66). Localized Ann Arbor stage IE EMZL and FL were frequently treated with external beam radiation therapy. DLBCL, MCL, and disseminated EMZL and FL were primarily treated with chemotherapy. EMZL and FL patients had a markedly better prognosis (10-year disease-specific survival of 92% and 71%, respectively) than DLBCL and MCL patients (10-year disease-specific survival of 41% and 32%, respectively). CONCLUSIONS: Four lymphoma subtypes were primarily found in patients with orbital lymphoma: EMZL, DLBCL, FL, and MCL. The histologic subtype was found to be the main predictor for outcome, with EMZL and FL patients having a markedly better prognosis than DLBCL and MCL.