Pseudotumoral Lesion as a Manifestation of Autoimmune Pancreatitis

Autoimmune pancreatitis is a chronic and benign disease of autoimmune etiology that can occur isolated or constitute a manifestation of immunoglobulin G4 (IgG4)-related disease (types 2 and 1, respectively). It is a pathological condition that can mimic pancreatic cancer by presenting as a mass in imaging studies and provoking symptoms such as obstructive jaundice and dramatic weight-loss. The inflammatory infiltrates in the pancreas can also produce endocrine dysfunction leading to diabetes. The authors report the case of a 68-year-old man that presented with unexplained weight loss and poorly controlled diabetes despite progressive pharmacological adjustments, with a later onset of obstructive jaundice, for which he underwent pancreaticoduodenectomy with the pre-operative diagnosis of pancreatic malignant neoplasm, which was posteriorly identified as type 1 autoimmune pancreatitis. In these cases, the differential diagnosis might be particularly challenging, requiring a high level of suspicion to avoid unnecessary procedures. Corticosteroid therapy can lead to the resolution of symptoms as well as glycemic control, and it is the cornerstone of IgG4-related disease treatment. However, corticosteroid-sparing agents may be of interest to achieve clinical suppression.