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 Table of Contents  
Year : 2020  |  Volume : 53  |  Issue : 3  |  Page : 113-116

Autoimmune pancreatitis type 2: Mimicking pancreatic cancer

1 Department of General Surgery, Chang Gung Memorial Hospital, Taipei, Taiwan
2 Department of Anatomical Pathology, Chang Gung Memorial Hospital, Taipei, Taiwan
3 Department of Medical Imaging and interventions, Chang Gung Memorial Hospital, Taipei, Taiwan
4 Department of General Surgery, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taipei, Taiwan

Date of Submission28-Nov-2019
Date of Decision30-Jan-2020
Date of Acceptance19-Mar-2020
Date of Web Publication30-May-2020

Correspondence Address:
Dr. Ta-Sen Yeh
5, Fu-Hsing Street, Kwei-Shan, Taoyuan
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/fjs.fjs_104_19

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Autoimmune pancreatitis (AIP) is a rare disease, which comprises two distinct forms of steroid response chronic pancreatitis. AIP type 2 with no association to IgG level and more confined to the pancreas makes it hard to differentiate with pancreatic cancer preoperatively. Here, we present two cases that were preoperatively diagnosed as pancreatic cancer but turn out to be AIP type 2. The first case is a 55-year-old male with epigastric pain, body weight loss and obstructive jaundice. He also had elevated liver enzyme, but tumor marker and IgG4 level were within normal range. The image studies showed the pancreatic head mass. The pylorus-preserving pancreaticoduodenectomy was performed. The second case is a 35-year-old female with epigastric pain and fever. The laboratory data were within the normal range except elevated C-reactive protein level. The magnetic resonance cholangiopancreatography showed a lobulated mass at the pancreatic tail with regional lymphadenopathy. The laparoscopic distal pancreatectomy with splenectomy was arranged for suspect pancreatic neoplasm. In summary, we had reviewed several studies and concluded several steps to help differential AIP to pancreatic cancer. This may help reduce the unnecessary pancreatic resection in the future.

Keywords: Autoimmune pancreatitis type 1, autoimmune pancreatitis type 2, pancreatic tumor, IgG4 antibody, pancreatectomy

How to cite this article:
Lin TA, Chen TC, Tseng JH, Yeh TS. Autoimmune pancreatitis type 2: Mimicking pancreatic cancer. Formos J Surg 2020;53:113-6

How to cite this URL:
Lin TA, Chen TC, Tseng JH, Yeh TS. Autoimmune pancreatitis type 2: Mimicking pancreatic cancer. Formos J Surg [serial online] 2020 [cited 2021 Aug 4];53:113-6. Available from: https://www.e-fjs.org/text.asp?2020/53/3/113/285396

  Introduction Top

Autoimmune pancreatitis (AIP) is a rare disease, which comprises two distinct forms of steroid response chronic pancreatitis. This unique form of pancreatitis often presents with obstructive jaundice with or without pancreatic mass. Here, we present two cases that were preoperatively diagnosed as pancreatic cancer but turn out to be AIP type 2 after tumor resection. This study is aimed to increase the awareness of AIP and help reduce unnecessary pancreatic tumor resection in the future.

  Case Report Top

Case 1

A 55-year-old male presented with intermittent epigastric dull pain with poor intake and body weight loss 6 kg in 1 month. The patient first attended to the regional hospital where abdominal echo and computed tomography (CT) showed intrahepatic biliary tree dilatation. The patient was referred to our medical center. On admission, physical examination showed icteric sclera and epigastric tenderness. Biochemistry examination showed total bilirubin of 6.6 mg/dL, amylase of 254 U/L, lipase of 690 U/L, alkaline phosphatase of 785 U/L, and aspartate aminotransferase of 252 U/L. Magnetic resonance cholangiopancreatography (MRCP) showed contrast enhancement of the pancreatic head tumor with long-segment stricture of the main pancreatic duct in the head portion with only mild dilatation of the distal main pancreatic duct [Figure 1]a. The serum IgG4 level was 67 mg/dL. CT-guided biopsy with 21G fine-needle aspiration cytology yielded negative for malignancy.
Figure 1: Case 1: (a) Pancreatic tumor over the pancreatic head (arrow). (b) The H and E stain, 1 × 40: The lymphoplasmacytic infiltration around pancreatic ducts and within lobules (arrowhead). Intraductal neutrophilic microabscess with polymorphous and lymphoplasmacytic infiltration (arrow). (c) Immunohistochemical stain of IgG, 1 × 400: The light brownish spots. (d) Immunohistochemical stain of IgG4, 1 × 400: The dark brownish spots. The IgG4/IgG ratio is <40%

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Based on inconclusive diagnosis amid pancreatic cancer and AIP, pylorus-preserving pancreaticoduodenectomy was performed. During the operation, the stony hard consistence of the entire length of the pancreas with remarkable soft lymphadenopathy over the common hepatic artery and extreme adhesions over the hepatoduodenal ligament and splenic–portal vein confluence was noted. The pathology turned out to be AIP [Figure 1]b, while immunohistochemical (IHC) study supported the diagnosis to be AIP type 2 [Figure 1]c and [Figure 1]d.

Case 2

A 35-year-old female presented with persistent epigastria with radiation to back and fever. She had undergone laparoscopic cholecystectomy for gallstone disease. Physical examination showed mild epigastric tenderness and moderate left flank-knocking pain. The laboratory data were within the normal range except C-reactive protein level of 210.9 mg/L. The CT of the abdomen showed swelling of the pancreatic tail with surrounding fat stranding, indicating acute pancreatitis and Balthazar Grade C. There was no biliary tree, common bile duct, or pancreatic duct dilatation. MRCP showed a lobulated mass measured 6.1 cm × 2.9 cm located at the pancreatic tail with homogeneous soft-tissue component and regional lymphadenopathy over the peripancreatic tail, left para-aortic, pancreatic head, and uncinate process [Figure 2]a. The serum level of CA 19-9, carcinoembryonic antigen (CEA), and IgG4 was 17.5 U/mL, 0.5 ng/mL, and 196 mg/dL, respectively. The patient underwent laparoscopic distal pancreatectomy with splenectomy for suspicion of pancreatic cancer. The hard and swollen pancreatic tail with adhesion over the spleen and Gerota's fascia was noted during surgery. The pathology report ended up being AIP [Figure 2]b. The IHC study further indicated the final diagnosis as AIP type 2 [Figure 2]c and [Figure 2]d. She had an acute pancreatitis episode 4 months after operation. The patient received steroid therapy starting from 30 mg per day of prednisolone, and the dose was gradually tapered.
Figure 2: Case 2: (a) The lobulated mass at the pancreatic tail (arrow). The local fat stranding suggests pancreatitis (arrowhead). (b) The H and E stain, 1 × 40: The lymphoplasmacytic, neutrophilic, and eosinophilic infiltrates, acinar atrophy, and fibrosis. The periductal inflammation, granulocytic epithelial lesions, intraluminal microabscesses, and phlebitis and focal fat necrosis were also seen. (c) Immunohistochemical stain of IgG, 1 × 400. (d) Immunohistochemical stain of IgG4, 1 × 400

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  Discussion Top

AIP is a rare disease, while AIP type 2 is even less common than type 1. The first case report of pancreatitis associated with elevated IgG level was published in 1961.[1] The AIP concept was eventually established by Dr. Yoshida et al. in 1995.[2] Later on 2010, AIP type 2 was divided from AIP type 1 due to the characteristic of nonelevated IgG level but still response to steroid therapy. The International Consensus Diagnostic Criteria (ICDC) was established on the next year, which showed a good sensibility and specificity in AIP type 1 but not as good in type 2.[1],[3]

Differential diagnosis

AIP type 2 is typically characterized with obstructive jaundice with or without pancreatic mass and no other organ involvement. Most of the patients have no autoimmune disease but might increase inflammatory bowel disease incidence. Reviewing the literatures, several studies had emphasized the difficulty of distinguishing AIP type 2 to pancreatic cancer before pancreatic tumor resection.[3],[4],[5] Dr. Peláez-Luna et al. reviewed the pathology outcome of all the pancreatic head mass who underwent the Whipple procedure. The result showed 70% as pancreatic cancer, 10% as chronic pancreatitis and 20% as AIP type 2. This suggest major operation took place in 30% of benign lesions. After analysis the AIP type 2 patients characteristic, they tend to be younger age, more abdominal pain episode, higher chances of collaborate with autoimmune disease. However, less presented with obstructive jaundice and image showed nondilated main pancreatic duct.[6]

Several considerations lead to over resection of the AIP type 2. The ICDC recommend consider those atypical imaging as pancreatic cancer first unless has strong collateral evidence.[1],[7] One of the cohort studies reported the small proportion of simultaneously AIP with pancreatic cancer. With the fear of malignancy, clinicians and patients may choose even more aggressive treatment to resect the mass.[8] However, the Korean prospective study suggested that “a 2-week steroid trial” in those equivocal cases might be one of the appropriate ways to differentiate AIP from pancreatic cancer.[9]They suggests take 2 weeks of steroid therapy in those equivocal cases before tumor resection. If the follow up imaging 2 weeks after showed decrease of tumor size, the AIP type 2 is more favor and the operation could be hold.

Even though facing the difficulty, we suggest the following steps for helping us to differentiate AIP type 1, AIP type 2, and pancreatic cancer. In the patient presents with pancreatic mass, first, we need to exclude those with typical pancreatic cancer presentation. For example, in the CT and/or MRI study, the pancreatic cancer presents as a hypoattenuating lesion, the mass effect on the pancreatic parenchyma, distal atrophy and the abrupt cutoff of the dilated pancreatic duct, double-duct signs, vessel encasement, lymphadenopathy, etc. Next, if the imaging doesn't fit the typical pancreatic cancer features, the AIP should be considered. Especially in those patients that is younger, symptomatic, collaborate with autoimmune disease and without dilation of the main pancreatic duct. AIP is more favorable. Then, check IgG4 level and tumor marker with CA 19-9 and CEA before the operation in every patient with pancreatic tumor or suspicious pancreatitis. The tissue biopsy for pathology proof is also indicated in this point. This help divide AIP to pancreatic cancer. Finally, in those equivocal cases, the “2-week steroid trial” may be helpful. After the patient takes steroid therapy for two weeks, the mass decreasing size may indicate AIP and this could help reduce the unnecessary operation. If the size is consistent or even larger, the sensitivity of pancreatic cancer increases, and the operation could be performed for definite diagnosis.

Therapeutic consideration

The AIP international treatment consensus combined both Western and Eastern experts' point of view was published in 2017.[7] In those AIP patients, 10%–25% are asymptomatic and may spontaneously improve without medication or intervention. The “watchful waiting” may be appropriate. However, those symptomatic patients could then receive steroid-based treatment. One of the international multicenter studies reported a high remission rate, 99.6% in AIP type 1 and 92.3% in type 2.[10]

Prognosis and prevention

The prognosis of AIP type 2 is a relatively good, and most of the patients could reach complete remission and need an only regular biochemical blood test and imaging follow-up. Currently, there was no evidence of increased incidence of pancreatic neoplasm or other kinds of autoimmune disease in the future. The relapse rate is significantly lower in AIP type 2 than in AIP type 1, as 9% versus 31%.[7] We are still at the beginning of understanding AIP type 2 in etiology, diagnosis, clinical presentation, management, and prognosis. Further studies and efforts are needed for better acknowledgment of the disease.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest

  References Top

Shimosegawa T, Chari ST, Frulloni L, Kamisawa T, Kawa S, Mino-Kenudson M, et al. International consensus diagnostic criteria for autoimmune pancreatitis: Guidelines of the international association of pancreatology. Pancreas 2011;40:352-8.  Back to cited text no. 1
Yoshida K, Toki F, Takeuchi T, Watanabe S, Shiratori K, Hayashi N. Chronic pancreatitis caused by an autoimmune abnormality. Proposal of the concept of autoimmune pancreatitis. Dig Dis Sci 1995;40:1561-8.  Back to cited text no. 2
Nagpal S, Sharma A, Suresh TC. Autoimmune pancreatitis. Am J Gastroenterol 2018;113:1301-9.  Back to cited text no. 3
Hart PA, Levy MJ, Smyrk TC, Takahashi N, Abu Dayyeh BK, Clain JE, et al. Clinical profiles and outcomes in idiopathic duct-centric chronic pancreatitis (type 2 autoimmune pancreatitis): The mayo clinic experience. Gut 2016;65:1702-9.  Back to cited text no. 4
Dickerson LD, Farooq A, Bano F, Kleeff J, Baron R, Raraty M, et al. Differentiation of autoimmune pancreatitis from pancreatic cancer remains challenging. World J Surg 2019;43:1604-11.  Back to cited text no. 5
Peláez-Luna M, Medina-Campos C, Uscanga-Domínuez L, Hernandez-Calleros J, Chan-Nuñez C, Negrete E, et al. A nondilated main pancreatic duct predicts type 2 autoimmune pancreatitis: Comparative study of resected pancreatic head masses. Digestion 2020;101:137-43.  Back to cited text no. 6
Okazaki K, Chari ST, Frulloni L, Lerch MM, Kamisawa T, Kawa S, et al. International consensus for the treatment of autoimmune pancreatitis. Pancreatology 2017;17:1-6.  Back to cited text no. 7
Macinga P, Pulkertova A, Bajer L, Maluskova J, Oliverius M, Smejkal M, et al. Simultaneous occurrence of autoimmune pancreatitis and pancreatic cancer in patients resected for focal pancreatic mass. World J Gastroenterol 2017;23:2185-93.  Back to cited text no. 8
Moon SH, Kim MH, Park DH, Hwang CY, Park SJ, Lee SS, et al. Is a 2-week steroid trial after initial negative investigation for malignancy useful in differentiating autoimmune pancreatitis from pancreatic cancer? A prospective outcome study. Gut 2008;57:1704-12.  Back to cited text no. 9
Kamisawa T, Shimosegawa T, Okazaki K, Nishino T, Watanabe H, Kanno A, et al. Standard steroid treatment for autoimmune pancreatitis. Gut 2009;58:1504-7.  Back to cited text no. 10


  [Figure 1], [Figure 2]


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