Facial numbness in a man with inguinal and retroperitoneal masses

Background A 37-year-old Brazilian man was admitted to Massachusetts General Hospital for evaluation of left-sided facial numbness, left-sided ataxia, dizziness, and vertigo. Seven weeks prior to admission, he reported numbness of the left oral cavity and tongue after a dental procedure. Three weeks prior to presentation, he developed left-sided incoordination with dizziness and vertigo. One week later, he noticed difficulty using a box cutter at work and presented to the emergency department for evaluation. A CT scan without contrast revealed no abnormalities and he was discharged home. Three days prior to admission, the patient developed diplopia. Cranial MRI revealed a 1.6 cm irregular enhancing mass in the left middle cerebellar peduncle. Neurologic examination was significant for diminished sensation over the left face to pinprick, left-sided dysmetria, and mild lateral instability of the trunk while walking.