Chronic rhinosinusitis is a condition characterized by inflammation of the paranasal sinuses causing several symptoms, including facial pain, anosmia, nasal drainage, and obstruction for a minimal duration of three months. It is a commonly occurring disease and is diagnosed through direct visualization or the detection of inflammation on a CT scan. A mucosal tissue biopsy typically reveals stromal fibrosis and an increase in submucosal glands, and infiltration of mixed mononuclear cells, neutrophils, and eosinophils may also be present but typically makes up less than 10% of the total cells. T helper type 2 releasing cytokines, interleukins (IL-5 and IL-13), as well as histamine, are frequently found in high concentrations in polyp tissue. We report a case of rare chronic rhinosinusitis. The patient's specimen shows a very high number of immunoglobulin G4 (IgG4)-positive plasma cells. Keywords: allergy; chronic rhinosinusitis; igg4-related chronic rhinosinusitis; invasive fungal rhinosinusitis; rhinosinusitis.

2023