A Masked Intruder: Extranodal Natural Killer/T-Cell Lymphoma Mimicking Preseptal Cellulitis.

Extranodal natural killer/T-cell lymphoma is a rare, aggressive, Epstein-Barr virus-associated malignancy. We reported an unusual case of a woman in her middle 40s presenting with progressive left-sided periorbital swelling, redness, and pain, initially treated as a refractory preseptal cellulitis. Despite aggressive antibiotic therapy, symptoms worsened. Imaging showed inflammatory stranding and phlegmonous enhancement involving the left orbit. A biopsy revealed the diagnosis of primary orbital extranodal natural killer/T-cell lymphoma (nasal type) without sinonasal involvement, which is extremely uncommon. This case emphasized the need to consider other noninfectious diagnoses in patients with preseptal cellulitis unresponsive to antibiotics.