Otologic Manifestations of IgG4-Related Disease: Literature Review and Report of Two Cases

Background: IgG4-related disease (IgG4-RD) is an inflammatory process. The literature on IgG4-RD is rather limited, with mastoid involvement being uncommon. In such cases, presentation may mimic other middle ear and mastoid cavity pathologies. Objective: To summarize findings of patients with IgG4-RD involving the mastoid. Methods: Description of two new cases and summary of findings with previous reports. Results: Nineteen cases of IgG4-RD with mastoid bone involvement were reported in the literature, the earliest appearing at the beginning of the previous decade. Most frequent symptoms included hearing deterioration, tinnitus and otalgia. In 58% of the cases, the process was restricted to otologic manifestations. In 7 out of 19 cases, tissue IgG4 levels were elevated. In all histopathologic samples taken from the operative sites, a dense lymphoplasmacytic cell infiltration was observed. Following definitive pathological diagnosis, the most common treatment was corticosteroids. Generally, the time from onset to final diagnosis was usually more than six months. The treatment is corticosteroids, followed by immunosuppressive agents such as rituximab, cyclophosphamide, and methotrexate. Conclusions: IgG4-RD involving the mastoid is a challenging condition, both in diagnosis and treatment. Hence, IgG4-RD should be included in the differential diagnosis of middle ear pathologies and include a multi-disciplinary team for treatment.