Otolaryngology Case Reports · Published 2026-07-13 · DOI 10.1016/j.xocr.2026.100761
Fadoua El Mourabit, M. Lahjaouj, M. Loudghiri, W. Bijou, Y. Oukessou, S. Rouadi, R. Abada, M. Roubal, M. Mahtar
Background: Immunoglobulin G4-related disease (IgG4-RD) is a chronic immune-mediated fibro-inflammatory disorder characterized by tumefactive lesions, dense lymphoplasmacytic infiltrates rich in IgG4-positive plasma cells, storiform fibrosis, and obliterative phlebitis. Although head and neck involvement is increasingly recognized, isolated disease of the pterygopalatine fossa with orbital extension remains exceptionally rare and may closely mimic aggressive neoplastic or infectious skull base lesions. Case presentation: A 62-year-old man with type 2 diabetes mellitus presented with progressive painful right-sided exophthalmos, retro-orbital headache, and visual impairment. Ophthalmological examination revealed decimal visual acuity of 1/10 in the right eye (equivalent to approximately 20/200 Snellen) and 10/10 in the left eye (20/20 Snellen), with preserved pupillary reflexes and right papilledema. Initial computed tomography suggested orbital cellulitis associated with chronic maxillary sinusitis. Subsequent magnetic resonance imaging demonstrated an infiltrative pseudotumoral lesion centered on the right pterygopalatine fossa extending to the orbit, orbital apex, infratemporal fossa, sphenoid sinus, and nasal cavity, with enlargement of the inferior rectus muscle. The radiological appearance strongly suggested an aggressive skull base malignancy. Serum IgG4 levels were elevated to approximately three times the upper limit of normal, while PET-CT excluded systemic involvement. Endoscopic biopsy revealed dense lymphoplasmacytic infiltrates, storiform fibrosis, and obliterative phlebitis. Immunohistochemistry demonstrated more than 30–50 IgG4-positive plasma cells per high-power field and an IgG4+/IgG + plasma cell ratio exceeding 40%, confirming IgG4-related disease. Treatment with oral prednisolone (0.6 mg/kg/day) resulted in only partial clinical improvement. Rituximab therapy (1000 mg intravenously on days 1 and 15) was subsequently administered, leading to partial regression of exophthalmos and significant radiological improvement during 12 months of follow-up. Conclusion: IgG4-related disease should be considered in the differential diagnosis of infiltrative lesions involving the pterygopalatine fossa and orbit. Because radiological findings may closely resemble malignant skull base tumors, histopathological and immunohistochemical confirmation is essential. Early recognition may prevent unnecessary aggressive procedures and allow timely initiation of effective immunomodulatory therapy, including rituximab in refractory cases.
Abstract from DOAJ. Public domain (CC0 1.0).
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Mourabit, F., Lahjaouj, M., Loudghiri, M., et al. (2026). IgG4-related disease of the pterygopalatine fossa with orbital extension mimicking an aggressive skull base tumor: A case report and literature review. Otolaryngology Case Reports. https://doi.org/10.1016/j.xocr.2026.100761