**4.4 Other organ involvement**

A type 1 AIP is a systemic disease; we can see frequently signs of the disease in other organs. Fibroinflammatory tumor-like pathology of lacrimal and salivary glands is clearly visible, palpable, and easy to access for a biopsy. However, other manifestations, as frequent bilateral nephritis, can be asymptomatic but easily detectable on the MR image (**Figure 4a**), frequently synchronic with the pancreatic disease. Peritoneal fibrosis and aortitis can occur in different times, before or later, as compared to AIP. In our experience PSC like cholangitis and bilateral multifocal nephritis were the most frequent extrapancreatic manifestations, found in 8 and 11 of our 44 type 1 patients, respectively [18]. Any of these manifestations, in particular when their histology confirms IgG4-related disease, can be considered as a definitive proof for type 1 AIP. For type 2, the association of IBD makes probable the diagnosis, but cannot be considered as a definitive proof.
