[Expression and significance of IgG4 in inflammatory disease of nasal cavity and paranasal sinuses].

Objective: To study the prevalence of IgG4-positive plasma cells in inflammatory disease of nasal cavity and paranasal sinuses and its association with IgG4-related sclerosing disease (IgG4-SD).

Methods: The expression of IgG4 and IgG in plasma cells of 103 cases diagnosed as inflammatory disease of nasal cavity and paranasal sinuses with dense lymphoplasmacytic infiltrate was studied by immunohistochemistry (EnVision) and quantitatively analyzed by medical image analysis system.

Results: Immunohistochemical study showed marked infiltration by IgG4-positive plasma cells (>50 per high-power field) in 28 cases, moderate infiltration (30 to 50 per high-power field) in 23 cases, mild (10 to 29 per high-power field) in 30 cases and negative (<10 per high-power field) in 22 cases (P < 0.05). Twenty-two cases studied fulfilled the diagnostic criteria of IgG4-SD (>50 IgG4-positive plasma cells per high-power field and IgG4-to-IgG ratio > 40%), including 3 cases of chronic sinusitis (3/20), 3 cases of nasal polyps (3/18), 3 cases of inflammatory pseudotumor (3/17), 4 cases of fungal sinusitis (4/20), 1 case of rhinoscleroma (1/12), 7 cases of Wegener's granulomatosis (7/11) and 1 case of Rosai-Dorfman disease (1/2).

Conclusion: Inflammatory disease of nasal cavity and paranasal sinuses fulfilling the diagnostic criteria IgG4-SD is not uncommon. Definitive diagnosis of IgG4-SD requires correlation with other clinical and laboratory findings. Some cases of unexplained inflammatory disease of nasal cavity and paranasal sinus may represent a member of the IgG4-SD spectrum. IgG4 carries diagnostic value in differential diagnosis of inflammatory disease occurring in nasal cavity and paranasal sinuses.