Eosinophilic Angiocentric Fibrosis Is a Form of IgG4-related Systemic Disease

Eosinophilic angiocentric fibrosis (EAF) is an uncommon tumefactive lesion of the orbit and upper respiratory tract of unknown etiology. The condition is characterized histologically by concentric layers of fibrosis around small-caliber arteries and a mixed inflammatory infiltrate dominated by eosinophils. After the serendipitous observation of an elevated serum concentration of IgG4 in 1 patient with EAF, we investigated the hypothesis that EAF...