IgG4-Related Disease Complicated by Brain Parenchymal Lesions Successfully Treated with Corticosteroid Therapy: A Case Report.

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is distinguished by the infiltration of IgG4-positive plasma cells in a variety of tissues and organs including the pancreas, salivary glands, retroperitoneal lesions, kidney, and lymph nodes with elevated serum IgG4 levels. Even so, central nervous system (CNS) lesions such as brain parenchymal lesions associated with IgG4-RD are scarce. So far, only six cases of IgG4-RD in relation with brain parenchymal lesions have been described, with its characteristics still being not clear. Here we have detailed a case of IgG4-RD with brain parenchymal lesions and reviewed previously-reported cases of IgG4-RD with brain parenchymal lesions. A 62-year-old Japanese male suffering from lung silicosis was admitted to our hospital for abdominal discomfort and altered consciousness. He has shown no major neurologic abnormalities except for drowsiness, urinary retention, and fecal incontinence. Brain magnetic resonance imaging has shown scattered hyperintense signals in the brain parenchyma. The serum IgG4 levels were elevated and systemic lymph nodes were enlarged. Biopsy from inguinal lymph nodes has shown massive infiltration of IgG4-positive plasma cells: the ratio of IgG4-positive/IgG-positive plasma cells was nearly 100%. Based on clinical courses, images, laboratory data, and pathological findings, a diagnosis of IgG4-RD that was complicated by brain parenchymal lesions and sacral nerve disturbance was confirmed. The patient was then given methylprednisolone pulse therapy (1g for 3 days) succeeding oral prednisolone (1 mg per body weight). The clinical and radiological improvements together with steroid therapy proposed IgG4-RD to be the cause of the lesions.