Inflammatory pseudotumour of the skull base: A case report and review of the literature

Inflammatory pseudotumours (IPTs) are non-malignant collections of mixed inflammatory and fibroblastic cells due to an unknown etiology. IPTs have been most commonly described in the gastrointestinal and respiratory tract, but can occur anywhere in the body. The diagnosis of IPT is one of exclusion and rheumatologists are often asked to assess for entities such as granulomatosis with polyangiitis (GPA) or IgG4- related disease. Here we describe a case of a 27 year old female who presented with several months of right sided temporal headache and new-onset dysarthria, dysphagia and rightward tongue deviation. MRI revealed a mass at the skull base extending into multiple cranial nerve foraminae. Blood work revealed negative ANCA studies, elevated inflammatory markers, and normal IgG4 and ACE levels. She also had an incidentally discovered pulmonary nodule that was biopsied and showed focal necrosis with no granulomas or vasculitis. The skull base mass was biopsied and found to be consistent with IPT, without any features of vasculitis, lymphoma, sarcoidosis, infection or IgG4-related disease. She initially improved with high dose glucocorticoids followed by two doses of IV cyclophosphamide but unfortunately worsened after several weeks. A second biopsy was done to ensure that her diagnosis was correct and was again consistent with IPT. Currently, she remains symptomatic on glucocorticoids and is awaiting Rituximab therapy. We reviewed the literature for similar cases of adult patients with IPT involving the skull base with cranial nerve involvement and found seven articles detailing 10 patients. The average age of reported patients was 44 ± 12 years. In most cases patients had symptoms that had been present for months to years. All patients had an acute deterioration that led to diagnosis of IPT, usually with vision symptoms, hearing loss or worsening pain. All patients underwent imaging to localize the IPT and all had biopsies performed for definitive diagnosis. Treatment of IPT varied, two patients were managed with surgery alone, eight had variable doses and durations of glucocorticoids, and four patients also received cyclophosphamide therapy. Four patients had recurrence of symptoms after initial treatment. Overall outcomes were favourable, with resolution of symptoms and improvement of neurological deficits in eight patients. Two patients died; one from sepsis and the other from internal bleeding after the IPT infiltrated a carotid artery. Inflammatory pseudotumours have diverse presentations that may mimic rheumatologic conditions. Rheumatologists are often asked to rule out other diseases as well as aid in management with immunosuppressive medications.