Relapsed Extranodal NK/T-Cell Lymphoma Presenting as Unilateral Third Cranial Nerve Palsy: A Rare Case Report

Extranodal natural killer/T-cell lymphoma (ENKTL) is a rare and aggressive form of non-Hodgkin lymphoma. It most commonly affects the nasal cavity and sinuses. While only few of cases of third cranial nerve palsy have been reported in association with diffuse large B-cell lymphoma and Burkitt lymphoma, its occurrence as a presenting feature of ENKTL is exceptionally rare. Here, we present a patient with isolated third cranial nerve palsy as the initial manifestation of relapsed ENKTL. A 67-year-old woman with a history of ENKTL in remission was admitted with bilateral periorbital swelling, nasal purulent discharge, and congestion following nasal reconstruction. She was diagnosed with preseptal cellulitis and sinusitis and subsequently treated with IV antibiotics. She later developed a right third nerve palsy with pupillary involvement. A CT angiogram ruled out an aneurysm, however brain MRI showed perineural spread affecting the cavernous sinus. Further cranial nerve involvement prompted a biopsy of the sinus, confirming ENKTL. A PET scan was done. No uptake in the brain, sinuses, or the rest of the body was observed. A bone marrow biopsy was subsequently performed revealing marrow involvement with ENKTL, suggesting metastatic spread beyond the sinuses. Unfortunately, the patient developed sepsis and subsequently passed away. This case emphasizes the importance of early consideration of malignancy who present with atypical neurological symptoms. Given the risk of false-negative imaging results, a multimodal approach is essential. This should include high-resolution MRI coupled with neuroradiological review, biopsy with histopathological analysis when feasible, FDG PET scan and lumbar puncture with CSF analysis.