The patient is a previously healthy African American male presenting with AIHA at age 14, managed with prednisone and rituximab. Two years after being diagnosed with AIHA, the patient had an ischemic stroke. Imaging demonstrated marked stenosis of bilateral internal carotid arteries and irregularities of Circle of Willis branches, and extensive collateral circulation formation, consistent with moyamoya disease.
The patient may be presenting with a genetic mutation predisposing him to moyamoya, with AIHA as an environmental trigger, but lack of significant family history weakens this hypothesis. Another suggested etiology is autoimmune, with presence of autoantibodies in AIHA. The association is weakened by lack of inflammatory or arteriosclerotic changes on pathological analysis of affected vessels in moyamoya in previous literature.
Association of moyamoya with hemoglobinopathies suggests that hypoxic anemia secondary to hemolytic processes leads to release of cellular mediators contributing to the pathophysiology. This is supported by literature indicating presence of smooth muscle hyperplasia contributing to vessel occlusion in moyamoya. This hypothesis may be most relevant in our case, as the patient’s presentation 2 years after diagnosis of AIHA is consistent with a chronic process.