IgG4-Related Sclerosing Disease of the Temporal Bone: A Systematic Review

OBJECTIVE: IgG4-related disease (IgG4-RD) involving the temporal bone is an uncommon and underrecognized pathology often mistaken for malignancy. This systematic review is the first that aims to thoroughly analyze IgG4-RD of the temporal bone. DATABASES REVIEWED: Ovid MEDLINE, EMBASE, Cochrane Library, and Google Scholar. METHODS: We used the following search keywords: "lgG4-RD," "skull," "skull base," "cranial," "temporal bone," "inner ear." We additionally manually searched the bibliographies of relevant articles. The JBI Critical Appraisal Checklist for Case Reports and Case Series was used to assess the risk of bias; because of the scarcity of the reports, data were available through limited case series and reports; thus, data synthesis was not possible. RESULTS: We identified 17 studies with 22 cases with temporal bone involvement. The most common presenting symptoms were hearing loss, otalgia, and headache. The mastoid and petrous bone were the most affected anatomical areas. Both computed tomography and magnetic resonance imaging were used. Biopsies showed the characteristic lymphoplasmacytic infiltrate in all cases, with histopathology being the diagnostic modality that set the diagnosis. Most patients were treated with corticosteroids ± surgery or a combination of corticosteroids and immunosuppressants with 95.5% symptomatic response and disease control. CONCLUSION: IgG4-RD of the temporal bone radiologically manifests as space-occupying, lytic lesions; clinically, it presents with vague otological symptoms. Diagnosis involves a thorough workup, with histopathology being crucial in setting a definite diagnosis. IgG4-RD tends to respond well to systemic corticosteroids, whereas surgery is mostly required for diagnostic purposes.