Primary Orbital Lymphoma Manifesting as Increased Intraocular Pressure: A Case Report.

BACKGROUND Lymphoma can involve any orbital soft tissue (excluding bone) and may mimic other orbital diseases, often leading to misdiagnosis. Early diagnosis improves both disease management and patient survival. This rare case provides insights into the early diagnosis and treatment of orbital lymphoma. CASE REPORT An 87-year-old Asian man presented with sudden swelling of the left eyelid, vision loss, and severe pain. His intraocular pressure increased, and vision eventually deteriorated to no light perception. Biopsy of the orbital mass revealed small cell malignancy. Immunohistochemistry showed CD20(+++), Bcl-6(+++), and other markers consistent with diffuse large B-cell lymphoma. The patient received combined chemotherapy and radiotherapy, which relieved swelling and pain but did not restore vision. CONCLUSIONS Orbital lymphoma may present with or without systemic symptoms. Its clinical and imaging features often overlap with other orbital diseases, contributing to misdiagnosis. Pathogenesis plays a critical role in prognosis, emphasizing the importance of early diagnosis to improve outcomes. This case is among the few reported in which initial presentation included elevated intraocular pressure.