April 20, 2023

Sinonasal lymphoepithelial carcinoma (SLEC) is an extremely rare malignant tumor of the sinonasal tract. In this case report, we present a case with locally advanced disease of the posterior ethmoid cells. We also aim to review the clinical, radiological and pathological features, as well as the available treatment strategies, contributing to the literature of this rare malignancy. Our patient presented with unilateral nasal congestion, discharge, recurrent epistaxis, aural fullness, diplopia and visual disturbance. Imaging revealed an extensive osteolytic lesion of the right nasal cavity with intraorbital and intracranial invasion. Histopatholog ical examination of posterior ethmoid cell mucosa demonstrated undifferentiated malignant cells, associated with lymphoplasma cytic infiltration, while the immunohistochemistry was positive for pancytokeratin. A final diagnosis of EBV-positive SLEC was rendered and the patient was treated with concomitant chemo-ra diotherapy. To our knowledge, this is the first case report of SLEC arising from the posterior ethmoid cells with invasion into the orbit and middle cranial fossa.