Idiopathic orbital inflammation with bone destruction and extension into the paranasal sinuses.

Idiopathic orbital inflammation developed in the right orbit of a woman in her mid-thirties, causing tearing, photophobia, diplopia, altered depth perception, proptosis, and pain on eye movements. Computed tomography disclosed a mass involving the intraconal and extraconal nasal right orbit, extending to the orbital apex with anterior displacement of the globe, effacement of the medial rectus muscle, portions of the fat plane, and the superior oblique muscle, and bone destruction with extension of the mass through the orbital floor into the superior maxillary sinus and through the lamina papyracea into the ethmoid sinus. Orbital biopsy disclosed dense fibrous connective tissue with numerous lymphocytes and macrophages. Immunohistochemical stains supported a diagnosis of idiopathic inflammatory pseudotumor involving the orbit and sinus mucosa. Treatment with a prednisone taper and a retrobulbar injection of triamcinolone acetonide have relieved her symptoms and diminished her proptosis. This patient highlights the rare potential of idiopathic orbital inflammation to erode though bone into adjacent cranial structures.