A 24-year-old male with headaches.

A 24-year-old man presented with a ten-day history of severe headache leading to collapse. CT studies showed filling defects involving the anterior, middle and posterior cerebral arteries and evidence of ischemia and infarction. Post-mortem examination revealed multiple cerebral infarcts secondary to an arteritic process composed of multi-nucleated giant cells, lymphocytes and histiocytes in both middle and anterior cerebral arteries and one posterior cerebral artery. Both carotid siphons and one renal artery segment were also involved. Extensive workup and stains for systemic and infectious causes were negative, leading to a diagnosis of atypical giant cell arteritis (GCA). Disseminated GCA involving extracranial arteries and the anterior, middle and posterior cerebral arteries leading to cerebral infarction has not been previously reported. We report this atypical case of disseminated GCA in a young patient with clinical features distinct from classic GCA (temporal arteritis) and discuss the differential diagnosis.