Diagnosis: Sinonasal idiopathic inflammatory pseudotumor (IIP) with orbital invasion
In the head and neck region, IIP most commonly involves the orbit and rarely involves the paranasal sinuses. The common symptoms of the sinonasal IIPs are pain around the involving sinus, nasal obstruction, and hemorrhagic rhinorrhea. Our patient had only orbital symptoms, such as periorbital edema, proptosis, global displacement, and binocular diplopia, with limitation on ocular motility; however, he had no nasal symptoms or painful cheek swelling. The mass was clinically silent until it invaded the orbital area, with periorbital edema, proptosis, and extraocular muscle involvement.