A lot of nerve.

A 71-year-old woman with a history of acute lymphoblastic leukemia presented with unilateral optic disc edema. Laboratory evaluations for infectious, inflammatory, and neoplastic etiologies were negative. Magnetic resonance imaging of the orbits with and without contrast demonstrated enhancement and thickening of the right optic nerve with mild stranding of the intraconal fat. She underwent three large-volume lumbar punctures, all of which were negative for malignancy. An optic nerve biopsy was ultimately performed, demonstrating malignant cells on immunohistochemical staining. This case illustrates a rare case of biopsy-proven leukemic infiltration of the optic nerve head as the presenting sign of leukemic relapse despite a negative systemic workup. Leukemic infiltration should be considered in the differential diagnosis for cases of acquired disc edema, especially in patients with a past medical history of leukemia.