Piao Y, et al. - With the intention of achieving a more accurate diagnosis, researchers sought to analyze the specific similarities and differences in clinicopathologic features between immunoglobulin G4 (IgG4)-related chronic rhinosinusitis (CRS), and Granulomatosis with Polyangiitis (GPA), Rosai-Dorfman disease (RDD) and Fungal Rhinosinusitis (FRS). Similar histopathologic features could be found in the sinonasal diseases GPA, RDD and FRS, such as increased numbers of plasma cells and fibrosis which were characteristic of IgG4-related CRS. Findings indicated that a comprehensive consideration combining the clinical signs and symptoms with a histopathological assessment of IgG4- positive plasma cells could yield accurate diagnoses of these conditions.