A case of probable IgG4-related disease involving the unilateral trigeminal nerve of the cheek region

Abstract

Immunoglobulin G4 (IgG4)-related disease comprises a recently recognized systemic syndrome char- acterized by mass-forming lesions that are found mainly in exocrine tissue and consist of lymphoplasmacytic infil- trates and sclerosis. There are numerous IgG4-positive plasma cells in the affected tissues, and the serum IgG4 level is increased in patients. The subject was a 77-year-old man with pathologically provable IgG4-related disease involving the unilateral trigeminal nerve in the left cheek region. A tumor-like lesion measuring 40 9 15 9 15 mm in the soft tissues of the left cheek was observed on com- puted tomography and magnetic resonance imaging, and extended along the infraorbital nerves to the anterior region of the maxilla. The mass was hypointense on T2-weighted images and showed mild contrast enhancement. Positron emission tomography showed accumulation in the left cheek (SUVmax: 3.9). Lymphoid follicles of various sizes surrounded by fibrosis were seen in the resected tumor. Immunostaining for IgG and IgG4 showed diffuse distribution of IgG- and IgG4-positive plasma cells in the interfollicular area, and the ratio of IgG4-positive plasma cells to IgG-positive plasma cells was 59 %. IgG4-related disease of the head and neck may be suggested by the combination of clinical signs and symptoms and radiologic findings of an infiltrative mass lesion. Although a definitive diagnosis cannot presently be obtained using IgG4-related disease comprehensive diagnostic criteria, we concluded that the present case was IgG4-related disease based on the good clinical course.