[Malignant lymphoma with IgG4-related disease arising in a very elderly man].

IgG4-related disease (IgG4-RD) which is characterized by an autoimmune abnormality and elevated serum IgG4 level often presents as swelling, nodules, and the thickening of multiple organs. It typically occurs in middle-aged to elderly patients, but its pathogenesis remains unclear. Lymphadenopathy is frequently seen in IgG4-RD, which clinically requires a differential diagnosis from malignant lymphoma. We herein report a case of malignant lymphoma with IgG4-RD arising in a very elderly man.An 85-year old man with a 6-year history of autoimmune pancreatitis was diagnosed as IgG4-related hypophysitis 13 months prior to admission. Hydrocortisone was prescribed for secondary adrenal insufficiency after this presentation. At 9 months before admission, he began to suffer from central diabetes insipidus, and desmopressin was also prescribed at that time. However, 9 months later, he presented with fever, weight loss, and systemic lymphadenopathy while demonstrating elastic hardness, flexibility, and no tenderness. A pathologic specimen obtained from a right axillary lymph node biopsy revealed diffuse large B cell lymphoma. Considering his age and performance status, palliative therapy was chosen, and thus prednisolone was administered. He was transferred to another hospital to receive palliative care on the 55th day after hospitalization.We should consider the clinical course, pathological findings, serum IgG4 level, and other involved organs in order to differentiate malignant lymphoma from IgG4-related lymphadenopathy. To our knowledge, this case is the oldest known patient to have ever been reported. Both IgG4-RD and malignant lymphoma are frequently seen in elderly people, therefore, we should deepen our knowledge of these diseases.