Eosinophilic Angiocentric Fibrosis of the Nasal Cavities: A Report of an Uncommon Lesion with Emphasis on the Etiology and Differential Diagnosis.

Background and Objectives : Eosinophilic angiocentric fibrosis (EAF) is an indolent but sometimes locally destructive lesion with a predilection for the sinonasal tract. Although it was first described in 1983, its etiology remains unknown. Some authors initially attributed EAF to trauma, hypersensitivity, and/or surgical manipulation, while it has been recently suggested to include EAF within the spectrum of IgG4-related systemic diseases. Materials and Methods : We report an uncommon case of idiopathic EAF in a 76-year-old male who developed two bilateral tumefactive masses in the nasal cavities. Results : As the histological examination showed a subepithelial proliferation of fibroblasts along with sclero-hyaline fibrosis around small-sized vessels (an "onion skin-like" pattern) and an eosinophils-rich inflammatory infiltrate, a diagnosis of EAF was rendered. The differential diagnosis included granuloma faciale, Wegener's granulomatosis, and Churg-Strauss syndrome. Conclusions : Pathologists should be aware of the possibility that this lesion can be part of the wide spectrum of IgG4-related systemic diseases by performing IgG4 investigations to assess adherence to IgG4-related systemic disease criteria.