Purpose: To assess the characteristics and treatment outcomes of patients with primary ocular adnexal lymphoma (OAL) in Northern Thailand.

Design: Retrospective cohort study.

Methods: Data was collected from electronic medical records and operative notes from Chiang Mai University Hospital between January 2009 and December 2014. All available tissue biopsies of 54 patients were reviewed by agreement of two pathologists. The clinical characteristics and treatment outcomes were collected and analyzed.

Results: A total number of 54 patients were identified of which 57.4% were female. The median age was 61.0 years (range, 4-86). The most common subtype of lymphoma was extranodal marginal zone lymphoma (ENMZL) of mucosa-associated lymphoid tissue (MALT) (n = 46, 85.2%). Seventy-five percent of the patients presented with a mass at the ocular adnexa, while 14.8% of the patients presented with proptosis. The sites of origin were as follows: lacrimal (46.3%), orbit (31.5%), conjunctiva (13%) and eyelid (7.4%). Two-thirds of the patients had Ann-Arbor Stage I, while 22% of patients had Stage IV. The majority of the patients (68.1%) had a low-risk international prognosis index (IPI). Treatment modalities involved field radiation (IFRT, 50%), chemotherapy (31.6%), combined chemoradiotherapy (7.9%) and surgical resection (10.5%). The overall response rate was 100% with a complete response rate of 77.8%. In patients with low-grade lymphoma, including MALT lymphoma, the 3-year progression-free survival (PFS) and overall survival were 69.9% and 92.5%, respectively.

Conclusion: ENMZL of MALT was the major subtype of primary OAL. Radiotherapy was an effective treatment for the lower stages of disease providing a high response rate and encouraging survival outcomes.