Lacrimal sac diffuse large B-cell lymphoma presenting as sudden-onset binocular diplopia

Introduction: Diffuse large B-cell lymphoma (DLBCL) is a prevalent subtype of non-Hodgkin lymphoma (NHL) affecting predominantly elderly individuals. Case description: A 68-year-old man with a history of hypertension, hyperlipidaemia and a small pituitary gland tumour presented with sudden-onset binocular diplopia and right-eye blurry vision. A magnetic resonance imaging (MRI) of the brain revealed enhancing soft tissue in the right superolateral orbit inseparable from the lacrimal gland, extending medially to the right superior rectus muscle and soft tissue. Further scanning showed widespread metastasis to the bilateral retroperitoneal lymph nodes, adrenal gland, spine and lymph nodes in the neck. A biopsy of the lacrimal gland confirmed DLBCL. Conclusion: Primary lacrimal gland DLBCL is a rare and delayed diagnosis that often stems from the resemblance of its clinical manifestations to more benign conditions such as dacryocystitis, dacryostenosis or mucocele. Timely recognition and accurate diagnosis are essential for initiating appropriate treatment and improving patient outcomes.