A 32-year-old man presented with severe headache, vomiting, and painless loss of vision of 5 days’ duration. He had no seizures, other neurologic deficits, or fever. Two months prior to presentation, he had an episode of hemoptysis of 30 to 50 mL, which resolved spontaneously; there was no recurrence. He reported one to two episodes of epistaxis each month that resolved spontaneously, since childhood. He had no known comorbid illness, prior surgeries, dental procedures, or blood transfusions. He denied any history of substance abuse. He observed that his father and brother also had recurrent self-limited episodes of epistaxis.