Autoimmune pancreatitis mimicking unresectable pancreatic cancer

K. Papp, E. Angst, S. Seidel, R. Flury-Frei, F. Hetzer

Objective

Autoimmune pancreatitis is a rare IgG4-associated disease. Two clinical and histological types have been described: type 1 is characzterized as lymphoplasmacytic sclerosing pancreatitis, whereas type 2 exhibits a duct-centric pancreatitis with granulocytic infiltration. Here we report the case of a patient with type 1 autoimmune pancreatitis with classical symptoms of pancreatic cancer.

Results

67-year-old male patient presented with painless jaundice, dark brown urine, acholia, the onset of a diabetic condition and a weight loss of 4 kg. His antecedent history showed an operated prostate cancer, malignant melanoma, borreliosis and polymyalgia rheumatica.

The computer tomography showed a double-duct sign and a tumorous process of the head of the pancreas was suspected, however the blood test showed normal values of the tumor markers. We indicated surgery suspecting pancreatic cancer: we found.

Figure 1: CT- Scan from 26.08.2013: typical “sausage- shaped” pancreas
Figure 2: CT- Scan from 20.11.2013: smaller pancreas without extended pancreatic duct

Infiltration of the superior mesenteric artery made the planned Whipple procedure impossible. The histological results of the biopsies showed chronic inflammation and fibrosis, but no sign of malignity. The secondary biopsies showed chronic periductal inflammation with infiltration of plasma cells, sclerosis, venulitis, parenchymal atrophy and positive immunostaining for IgG4, leading to the diagnosis of an IgG4-related pancreatitis.

Figure 3: Histology (HE) showing a chronic inflammation of the pancreas
Figure 4: Histology (immunostaining) showing IgG4- positive cells
Figure 5: Histology (immunostaining) showing IgG4- positive cells

We then determined IgG4 in the serum, which was elevated.

The computer tomography 6 weeks later presented a narrower pancreas without any signs of a tumorous component. As the patient was asymptomatic, no further therapy was needed.

Conclusion

Type 1 autoimmune pancreatitis was diagnosed in our patient typically occurring in men over 50 characterized by lymphoplasmacytic sclerosing pancreatitis. This disease mimicks pancreatic cancer in the imaging procedure and causes obstructive jaundice. It is associated with several extrapancreatic autoimmune diseases involving the lymph nodes, salivary glands or the breasts. The treatment is non-operative with steroid medication and is monitored by IgG serum levels.