Microscopic polyangiitis associated with subarachnoid hemorrhage.

Microscopic polyangiitis (MPA), an anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, is a systemic disease that damages all organs through predominantly affecting small vessels. However, few cases of MPA are related to aneurysms on medium-sized muscular vessels, and whether subarachnoid hemorrhage (SAH) is associated with MPA is still unclear. An 85-year-old woman with rapid progressive glomerular nephritis caused by MPA complained of sudden severe headache due to SAH 2 days after admission and subsequently underwent surgery. Cerebrovascular disease occurring simultaneously with MPA might result in poor prognosis, and the complications exacerbate the condition and lead to high mortality; thus, physicians should pay more attention to cerebral aneurysms concurrent with MPA. Among patients with MPA, it is important to identify priority cases and investigate the intracranial vessel environment. To the best of our knowledge, this is a rare report about SAH associated with MPA. We recommend that the presence of cerebrovascular disease should be considered in patients with MPA to improve their prognosis.