Peripheral T-cell lymphoma that developed during the follow-up of IgG4-related disease.

IgG4-related disease is a recently recognized fibroinflammatory disorder characterized by extensive IgG4-positive plasma cell and lymphocyte infiltration of various organs. The pancreatic manifestation of IgG4-related disease is called autoimmune pancreatitis (AIP), in which autoimmune mechanisms are likely involved. On the other hand, some autoimmune and chronic inflammatory disorders, such as Sjögren's syndrome and rheumatoid arthritis, are associated with increased risks of non-Hodgkin lymphoma (NHL).