Probable Immunoglobulin Subtype—G4-Related Disease in the Head and Neck from Foreign Body Injection: A Case Report

Introduction Immunoglobulin subtype G4-related disease (IgG4-RD) is a fibroinflammatory disease of unknown etiology, with manifestations involving nearly every organ system. Its association with foreign bodies is not established. Here, we present a novel case of IgG4-RD in response to foreign body injection. Case Description A 58-year-old woman presented with history of persistent left facial pain, xerophthalmia, blurred vision, and trismus. The patient's medical history was significant for left-sided temporomandibular joint (TMJ) reconstruction with silicone injection into the joint. Magnetic resonance imaging revealed a lesion in the left skull base. Biopsies demonstrated the cardinal histopathological features of IgG4-RD. The patient was treated with a tapering dose of prednisolone followed by rituximab, resulting in tumor shrinkage and resolution of her symptoms. Discussion This is the first reported case of IgG4-RD potentially precipitated by a foreign body, in this case injected silicone into the TMJ. The pathogenesis and etiology of IgG4-RD is still not fully elucidated, but allergic and reactive inflammatory reactions have been implicated in the disease process. This case report should raise the idea of reactive foreign bodies as a causative agent for IgG4-RD.