Objective: Natural killer T-cell lymphoma (NKTL) is a highly malignant tumor that typically arises in the nose and/or paranasal sinuses. Isolated orbital involvement by NKTL is extremely rare, and only few case reports exist in the literature. Herein, we report a case of primary orbital NKTL in a young patient who showed very good response to chemotherapy with the SMILE regimen.

Methods: A 28-year-old healthy female presented to us with epiphora and fullness of the lower eyelid. She had previously been diagnosed as orbital pseudotumor and was prescribed oral steroids. However, there was no response to the treatment. She also had a history of recurrent sinusitis. An incision biopsy revealed NKTL. A systemic workup did not reveal any other site of involvement. The patient received 6 cycles of chemotherapy (SMILE) and external beam radiotherapy.

Results: The tumor showed complete regression after 2 cycles of chemotherapy. The patient is disease free at 24 months of follow-up.

Conclusions: Reported median survival for primary orbital NKTL is extremely poor. This is perhaps the first report of a primary orbital NKTL demonstrating a remarkable treatment response to a newer chemotherapy regimen (SMILE) in combination with radiotherapy.