Immunoglobulin G4-related disease of the paranasal sinuses.

Immunoglobulin G4-related disease (IgG4-RD) is becoming increasingly documented. It was first described in relation to autoimmune pancreatitis. Features of the disease include tissue infiltration by IgG4 plasma cells with associated fibrosis and the growth of pseudotumours. A 71-year-old woman presented with increasing right cheek swelling and mild proptosis. Ten years earlier, she had a similar presentation and was diagnosed with an inflammatory pseudotumour. Examination revealed a lesion in the right nasal cavity. CT and MRI confirmed a mass within the right maxillary antrum extending into the nasal cavity. Endoscopic biopsies showed florid plasma cell infiltrate with marked increase in IgG+ plasma cells. Immunostaining expressed IgG4 (70%). She was started on a course of prednisolone and her symptoms resolved. IgG4-RD is becoming an emerging disease entity. Its involvement in the paranasal sinuses can mimic nasal tumours. Major surgical resection should be avoided as patients can often be treated medically.