IgG4-Related Disease of the Skull and Skull Base, A Systematic Review and Report of Two Cases: Review of Skull Base IgG4-Related Disease.

Abstract 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 of 2 cases of IgG4-RD in the skull base highlighting the diagnostic challenges with assessment of these skull base lesions was performed, and a systematic review of relevant literature summarized. Results A systematic review of literature conducted in accordance with PRISMA guidelines identified 113 publications 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 co-administered with immunosuppressive agents such as rituximab. Prevalence appeared to be equal between sexes, and serum IgG4 levels were elevated in 61% of cases. Delayed diagnosis and a need for multiple biopsies was reported in numerous cases. Two cases of skull base IgG4-RD from the authors institution demonstrate the variable presentations of this disease. More invasive surgical biopsies were required in both cases, and corticosteroid treatment led to significant clinical improvement. Conclusion IgG4-RD is an uncommon condition with a growing body of reported cases that can affect the skull base and calvarium and should be in the differential diagnosis as delay in diagnosis and treatment may be common.