IgG4-related disease presenting with destructive sinonasal lesion mimicking malignancy.

IgG4-related disease is a newly recognized systemic fibroinflammatory disorder. We report a 36-year-old man who presented with intractable right nasal pain and frontal headache for 1 month. Computed tomography revealed an ill-defined lesion with bony erosion over the right anterior ethmoid sinus and middle turbinate. The lesion was resected through endoscopic anterior ethmoidectomy and middle turbinectomy. IgG4-related disease was definitively diagnosed according to histopathological features. Prednisolone was administered postoperatively. IgG4-related disease presenting with destructive sinonasal lesion mimicking malignancy is rare. Awareness is essential to avoid delayed diagnosis or unnecessary invasive intervention, because the disorder responds to glucocorticoid and immunosuppressant therapy.