Focal Mass-Forming Autoimmune Pancreatitis Mimicking Pancreatic Cancer: Which strategy?

Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis that predominantly affects men in their fifth and sixth decades and often presents with obstructive jaundice and pancreatic enlargement. It is relatively easily diagnosed by characteristics of diffuse swelling of parenchyma and irregular narrowing of the main pancreatic duct. However, focal mass-forming AIP is hard to distinguish from pancreatic cancer. Problematic issue : How to differentiate a focal AIP from a pancreatic cancer and avoid a heavy and unnecessary surgical treatment?. Summary of the observation : We report three cases of mass-forming autoimmune pancreatitis that were preoperatively suspected to be pancreatic cancer, and review their clinical, radiological and histological features. We emphasize on the strategy of diagnosis and we try to understand the histopathological features of this disease. Conclusion : In patients with obstructive jaundice suggestive of pancreatic carcinoma, AIP should be considered in the differential diagnosis to avoid unnecessary laparotomy or pancreatic resection. To the best of our knowledge, this report is from the rare publications to present a histopathological comparison of mass-forming AIP with the adjacent uninvolved pancreatic tissues.