A rare case of IgG4-related systemic disease manifesting with pancreatic head mass mimicking borderline resectable cancer

INTRODUCTION: Autoimmune pancreatitis (AIP) is a rare pancreatic disorder among chronic pancreatitis that can mimick pancreatic cancer (PC). Patients with type 1 AIP usually present obstructive jaundice associated with high level of IgG4 in serum and a pancreatic mass at radiological imaging; these disorders may be associated with other organs lesions presenting the same histopathological features, and in these cases AIP should be considered a pancreatic localization of an IgG4-related systemic disease. PRESENTATION OF CASE: We report the case of a young man with initial suspect of PC to be treated with surgery, and final diagnosis of AIP in the context of an IgG4-related systemic disease. DISCUSSION: Because of its similar features, several algorithms have been proposed for AIP diagnosis, based on combination of clinical/serological and radiological criteria. However, histology represents the only way to obtain definitive diagnosis, even if sometimes it is difficult to obtain biological samples. CONCLUSION: IgG4-related systemic disease must be taken into account among differential diagnosis during the workup for PC, in order to avoid unnecessary surgery.