CD56 negative extranodal NK/T-cell lymphoma of the orbit mimicking orbital cellulitis.

INTRODUCTION: To report a case of Extranodal NK/T-cell lymphoma of the orbit mimicking orbital cellulitis. CASE DESCRIPTION: A 52-year-old healthy male presented to our institution after 3 months of treatment for sinusitis with antibiotics and steroids. The patient was transferred due to the presence of an "orbital abscess" on CT with orbital signs that not responding to antibiotics. Clinical examination was significant for decreased vision in the affected orbit of 20/50, a trace RAPD OS, elevated IOP of 30 OS, proptosis and grossly decreased motility with diplopia, periorbital edema and chemosis. Dilated funded exam was unremarkable. CT imaging demonstrated a left sided pan-sinusitis, a medial "orbital process" with proptosis and erosion of the cribiform plate. The patient was taken for an emergent orbital exploration for histopathologic diagnosis. Intraorbital and sinus biopsy was consistent with extranodal NK/T-cell lymphoma, with extension into the skull base and left orbital space. The patient was started on radiation therapy followed by chemotherapy. COMMENTS: The authors demonstrate how the acute presentation of an aggressive extranodal NK/T-cell lymphoma can present in a similar fashion as orbital cellulitis. Additionally, the case highlights that a unilateral pansinusitis with involvement of the skull base and orbit is likely due an aggressive malignant process in an immune competent patient.