Aggressive natural killer/T-cell lymphoma masquerading as acute orbital hemorrhage: a case report.

Natural killer T-cell lymphoma (NKTCL) is a highly aggressive tumor that usually affects the nasal cavity and/or paranasal sinuses. Primary orbital NKTCL is extremely rare, with only a few cases reported in the literature. The clinical presentation of orbital involvement by NKTCL is atypical and usually misdiagnosed as orbital cellulitis or orbital pseudotumor. A 23-year-old male patient was admitted to our hospital complaining of severe eye pain and manifested as acute orbital hemorrhage. Isolated orbital natural killer T-cell lymphoma (NKTCL) was confirmed by biopsy. This patient's orbital NKTCL did not respond to CHOP (cyclophosphamide, epirubicin, vincristine, prednisone) chemotherapy, but shrank significantly after receiving 1 cycle of C-SMILE (chidamide, steroid, methotrexate, isophosphamide, L-pegaspargase, etoposide). However, he still died after 3 cycles of C-SMILE chemotherapy at a follow-up time of 4 months. Primary orbital NKTCL can present clinically as a rare acute orbital hemorrhage, and the disease is aggressive and has a poor prognosis.