We report a case of a young female patient who was diagnosed with a marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT lymphoma) of the lacrimal sac which mimicked dacrocystitis.

A 23-year-old female suffered from epiphora for 3 years in the right eye. She had swelling and a painful lesion at the lacrimal sac 4 months prior and was referred to our hospital due to nasolacrimal duct obstruction and dacryocystitis. Lacrimal irrigation was performed with no passing and regurgitation with mucoid discharge. We performed orbital computed tomography and magnetic resonance imaging which showed a suspected tumor of the lacrimal sac in the right eye. We then performed excision and biopsy of the tumor through the skin approach. The patient was diagnosed with a MALT lymphoma with no systemic involvement. After six cycles of chemotherapy involving rituximab with cyclophosphamide, vincristine, and prednisone, the lesion of the mass and the painful symptoms decreased, which was regarded as a complete response. However, epiphora and eye discharge persisted, showing a nasolacrimal duct obstruction, so we performed endoscopic dacryocystorhinostomy with a lacrimal sac biopsy. The histological examination showed chronic inflammation, but not lymphoma. There was no recurrence of lymphoma at one year postoperatively.

If there is an epiphora and palpable lesion in the lacrimal sac area, MALT lymphoma mimicking dacyocystitis may be suspected. After the lymphoma is first diagnosed by excision and biopsy, systemic chemotherapy with dacryocystorhinostomy could be an effective treatment.