IgG4-Related Disease of the Skull and Skull Base–A Systematic Review and Report of Two Cases

Objective: IgG4-related disease (IgG4-RD) is an inflammatory process that uncommonly can present in the skull base and calvarium and mimic a tumor but the nature of this condition is not well summarized in the neurosurgical literature. Methods: A review was performed of 2 cases of IgG4-RD in the skull base highlighting the diagnostic challenges with assessment of these skull base lesions, and a systematic review of relevant literature was carried out. Results: A systematic review of the literature conducted in accordance with PRISMA guidelines identified 113 articles, with 184 cases of IgG4-RD in the skull base or calvarium. The most commonly affected locations include the meninges, cavernous sinus, base of the posterior fossa, clivus, and mastoid bone. Headache, visual and auditory disturbances, cranial nerve dysfunction, and seizures were the most common presenting symptoms. Medical treatment was highly successful and most commonly consisted of corticosteroids coadministered with immunosuppressive agents such as rituximab. Prevalence seemed to be equal between sexes, and serum IgG4 levels were increased in 61% of patients. Delayed diagnosis and a need for multiple biopsies were reported in numerous cases. Two cases of skull base IgG4-RD from the authors' institution show the variable presentations of this disease. More invasive surgical biopsies were required in both cases, and corticosteroid treatment led to significant clinical improvement. Conclusions: IgG4-RD is an uncommon condition with an increasing body of reported cases that can affect the skull base and calvarium and should be in the differential diagnosis, because delay in diagnosis and treatment may be common.