A 25-year-old man with human immunodeficiency virus (HIV) infection who was receiving highly active antiretroviral therapy presented with a 1-week history of diplopia and headache. The CD4 count was 218 cells per cubic millimeter, and the viral load was 50,000 copies per milliliter.
The neurologic examination revealed an inability to abduct the right eye with horizontal gaze, a finding that was consistent with an isolated right abducens nerve palsy (rightward gaze, Panel A; leftward gaze, Panel B). The examination of other cranial nerves was normal. The remainder of the motor and sensory examination was within normal limits.
The patient reported having had low back pain and constipation for the previous week. There was no history of bowel or bladder incontinence. A gadolinium-enhanced magnetic resonance image of the brain showed a minimally enhancing mass filling and expanding the right cavernous sinus (Panel C, arrow). Lumbar-spine imaging showed a mass with similar radiographic characteristics involving the ventral epidural compartment. Biopsy of the spinal lesion revealed diffuse large-B-cell lymphoma. A chemotherapeutic regimen of cyclophosphamide, doxorubicin, vincristine, and prednisolone, along with the monoclonal antibody rituximab (R-CHOP), was started. Progressive leg weakness from spinal involvement developed, and the patient had a poor response to corticosteroids and radiation therapy and died 3 months later.