Concomitant occurrence of Mikulicz's disease and immunoglobulin G4‐related chronic rhinosinusitis: a clinicopathological study of 12 cases

Aims Concomitant occurrence of Mikulicz's disease ( MD ) and immunoglobulin (Ig)G4‐related chronic rhinosinusitis (IgG4‐related CRS ) is extremely rare. We evaluated the clinicopathological features of MD patients with concomitant IgG4‐related CRS ( CRS ‐ MD ). Methods and results Twelve CRS ‐ MD patients were evaluated clinically and biopsy samples were taken from the lacrimal/salivary glands ( n  = 12) and nasal mucosa ( n  = 7) for assessment of IgG4‐positive cells, using immunohistochemical techniques. Similarly, nine MD patients and 10 patients with common CRS were evaluated as controls. CRS ‐ MD patients had higher serum IgG and IgG4 concentrations than MD patients ( P  < 0.05 for both). Lymphoplasmacytic infiltration, lymphoid follicle formation and sclerosis was prominent in the lacrimal/salivary glands in both groups; however, the magnitude of IgG4‐positive plasma cells infiltration in the CRS ‐ MD group was significantly higher compared to the MD group ( P  = 0.004). Similarly, evaluation of nasal mucosa revealed greater lymphocyte, plasma cell and eosinophil infiltration and lymphoid follicle formation, together with significantly higher IgG4‐positive plasma cell infiltration in the CRS ‐ MD group compared to the common CRS group ( P =  0.004). Conclusions Concomitant MD and IgG4‐related CRS were characterized by a combination of IgG4‐positive plasma cells infiltration in the lacrimal/salivary glands and the nasal mucosa and increased serum IgG4.