Primary Skull Base Lymphoma Presenting With Ipsilateral Abducens Nerve Palsy: A Case Report.

A 66-year-old woman with no prior medical history presented to the emergency department with diplopia and parosmia. The neurological examination identified an isolated left abducens nerve (CN VI) palsy. A head CT scan, followed by a brain MRI, showed a large, locally advanced tumour in the left sphenoid sinus with extensive skull base involvement and perineural extension into the left orbit. The histopathological analysis of the sphenoid sinus biopsy revealed high-grade diffuse large B-cell lymphoma. A PET scan confirmed this was a primary bone lymphoma. MRI of the pituitary, without contrast, six weeks following the initial imaging showed a more extensive local tumour extension. The patient was initially treated with MATRIX chemotherapy and targeted therapy. This case report describes a rare presentation of primary skull base lymphoma with abducens nerve palsy.