Pitfalls in the diagnostic procedure after initial radiographic presentation of a pancreatic tumor: Case series of patients diagnosed with autoimmune pancreatitis and pancreatic cancer

Introduction:

Tumor – according to its original meaning – refers to the swelling of tissue. Both inflammation and neoplasia can be the cause of a tumor. A relatively new entity in the history of gastroenterology is autoimmune pancreatitis characterized by diffuse or focal inflammation of the pancreas, a certain histological picture and a response to steroids.

Case 1:

A 58 year old female patient presented with diffuse abdominal pain radiating to her back and occasional night sweats. In an MRI of the abdomen thickening of the pancreatic body and tail in addition to a loss of lobulation as well as late enhancement in venous phase became apparent. To substantiate the suspected diagnosis of autoimmune pancreatitis an endosonographic biopsy of the pancreas revealed the histological picture of IgG4-dominated CD138-positive plasma cells. An elevated serum IgG4 of 833 mg/dl was measured. Regarding her additional diagnoses of autoimmune gastritis, alopecia, vitiligo and Hashimoto's thyreoditis the gastric tissue was analyzed on its IgG4 fraction compared to all CD138 positive plasma cells. Its elevation led to the diagnosis of an IgG4-associated systemic disorder and close consecutive follow-up with radiological and clinical response to steroids fortified the diagnosis.

Case 2:

A 72 year old male patient presented with a painless icterus and a weight loss of 8 kg in two months. Lipase was elevated at 574 U/l, while IgG4 was normal. Elevated inflammatory markers combined with an elevation in cholestasis parameters led to the initial diagnosis of cholangitis. An ERC revealed a distal stenosis of the common bile duct (due to tumor compression). A complementary abdominal CT scan showed an irregularly margined hypodense lesion (3 × 2 cm) in the pancreatic head without infiltration of the vessels. Due to the suspected diagnosis of a pancreatic cancer surgery was performed which revealed the histomorphological picture of an autoimmune pancreatitis with pancreatic intraepithelial neoplasia (PanIN 1).

Case 3:

A 36 year old male patient presented with recurrent left-sided abdominal pain and a weight loss of 7 kg in three months. Cross-sectional imaging showed a solid lesion at the pancreatic body-tail transition zone. A biopsy showed no malignancy or autoimmune pancreatitis. CA 19 – 9, CEA and Chromogranin A were within the normal range, while there was a discrete increase in IgG4. Therefore a steroid treatment was initiated to observe a possible response after two weeks suggestive of an autoimmune pancreatitis. In the follow-up MRI scan the lesion grew with infiltration of the splenic vein. Consequently, the steroid treatment was discontinued instantly and a resection of the pancreatic body and tail was performed. Histology showed a neuroendocrine carcinoma (pT2, pN1 (3/25), cM0, L0, V0, G2, Ki67 15%).

Conclusion:

The diagnostic evaluation of a pancreatic tumor is a challenging task. It is important to think of both neoplastic as well as inflammatory, especially autoimmune, causes that can look very similar radiographically.