In 1961, Sarles et al. [
Clinically, AIP is characterized by protean symptoms that have many features in common with pancreatic cancer. These symptoms include abdominal pain, obstructive jaundice, weight loss, steatorrhea, new-onset diabetes mellitus (DM), and elevated levels of serum tumor markers. Hardacre et al. in their single institutional study reported that about 2.5% of pancreatoduodenectomies were performed in AIP patients following a mistaken diagnosis of pancreatic cancer [
The diagnosis of AIP is challenging as it closely mimics pancreatic cancer. We further report a case of a 50-year-old Caucasian woman who presented with epigastric pain, nausea, vomiting, and jaundice. Subsequent workup revealed AIP as the etiology of her symptoms, and she was treated effectively with steroids.
A 50-year-old Caucasian woman presented to our hospital with 2-day duration of epigastric pain, nausea, vomiting, and jaundice. Her physical examination was unremarkable except for scleral icterus. An abdominal examination revealed epigastric tenderness without rebound. Laboratory investigations revealed hemoglobin 12.9 g/dL, white blood cell count 9.6/
MRCP images arrow showing sausage-like pancreas in delayed phase.
Endoscopic ultrasound images arrows showing (clockwise) (a) CBD stricture, (b) dilated CHD, (c) reactive lymph node, and (d) homogenous pancreatic body.
ERCP arrows showing CBD and MPD strictures pre stent insertion (a) and (b); post stent insertion (c) and (d) (clockwise).
Common bile duct stricture
Main pancreatic duct stricture
Stent in common bile duct
Stent in main pancreatic duct
Autoimmune pancreatitis is rare disease with a much lower rate of incidence than its principal differential diagnosis, pancreatic cancer. The overall incidence and prevalence are still unclear owing to lack of prospective natural history studies. Study series from Japan have reported the prevalence of autoimmune pancreatitis in a range between 5 and 6% of all patients with chronic pancreatitis of which 6–8% (0.82 per 100,000) had pancreatic resections performed for presumed pancreatic cancer [
The histopathological hallmark findings in patients with AIP include dense infiltration of T lymphocytes, IgG4-positive plasma cells, storiform fibrosis, and obliterative phlebitis in the pancreas; this form is termed lymphoplasmacytic sclerosing pancreatitis (LPSP) [
In 2011, an international panel of experts met during the 14th Congress of the International Association of Pancreatology held in Fukuoka, Japan, and an international consensus diagnostic criterion for AIP was proposed [
Level 1 and level 2 criteria for type 1 AIP.
Criterion | Level 1 | Level 2 |
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Parenchymal imaging | Typical: diffuse enlargement with delayed enhancement (sometimes associated with rim-like enhancement) | Indeterminate (including atypical): segmental/focal enlargement with delayed enhancement |
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Ductal imaging (ERP) | Long (>1/3 length of the main pancreatic duct) or multiple strictures without marked upstream dilatation | Segmental/focal narrowing without marked upstream dilatation (duct size, <5 mm) |
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Serology | IgG4, >2x_upper limit of normal value | IgG4, 1-2x_upper limit of normal value |
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a or b | a or b | |
(a) Histology of extrapancreatic organs | (a) Histology of extrapancreatic organs including endoscopic biopsy of bile duct | |
Any three of the following: | Both of the following: | |
(1) Marked lymphoplasmacytic infiltration with fibrosis and without granulocytic infiltration | (1) Marked lymphoplasmacytic infiltration with fibrosis without granulocytic infiltration | |
(2) Storiform fibrosis granulocytic infiltration | (2) Abundant (>10 cells/HPF) IgG4-positive cells | |
Other organ involvement (OOI) | (3) Obliterative phlebitis | |
(4) Abundant (>10 cells/HPF) IgG4-positive cells | ||
(b) Typical radiological evidence | (b) Physical or radiological evidence | |
At least one of the following: | At least one of the following: | |
(1) Segmental/multiple proximal (hilar/intrahepatic) or proximal and distal bile duct stricture | (1) Symmetrically enlarged salivary/lacrimal glands | |
(2) Retroperitoneal fibrosis | (2) Radiological evidence of renal involvement described in association with AIP | |
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LPSP (core biopsy/resection) | LPSP (core biopsy) | |
At least 3 of the following: | Any 2 of the following: | |
Histology of the pancreas | (1) Periductal lymphoplasmacytic infiltrate without granulocytic infiltration | (1) Periductal lymphoplasmacytic infiltrate without granulocytic infiltration |
(2) Obliterative phlebitis | (2) Obliterative phlebitis | |
(3) Storiform fibrosis | (3) Storiform fibrosis | |
(4) Abundant (>10 cells/HPF) IgG4-positive cells | (4) Abundant (>10 cells/HPF) IgG4-positive cells |
Reproduced with permission from 2012 Kamisawa, Tabata, Hara, Kuruma, Chiba, Kanno, Masamune, and Shimosegawa.
AIP should always be included in the differential diagnosis particularly in elderly presenting with obstructive jaundice and a pancreatic mass. Prior to initiation of therapy, it is of paramount importance to differentiate AIP from pancreatic cancer. Various strategies help differentiate the clinical, immunological, and radiological presentations in between AIP and pancreatic cancer. Obstructive jaundice induced by bile duct stenosis secondary to pancreatic cancer typically progresses steadily, whereas the jaundice of AIP in IgG4-related sclerosing disease sometimes fluctuates or, in rare cases, improves spontaneously [
Radiological studies aid in differentiation based on the characteristic features on computed tomography (CT) and magnetic resonance imaging (MRI) that include diffuse or focal pancreatic enlargement, a peripancreatic capsule-like rim, enhancement at the late phase of contrast-enhanced images, and abnormal signal intensity on MRI. Diffuse enlargement of the pancreas and effacement of the lobular contour of the pancreas, the so-called “sausage-like” appearance, are a typical finding in AIP and are rarely seen in pancreatic cancer. On delayed phase of dynamic CT and MRI, enhancement of an enlarged pancreas is characteristic of AIP. As fibroinflammatory changes involve the peripancreatic adipose tissue, a capsule-like rim surrounding the pancreas is specifically detected in some AIP patients [
The hallmark finding on endoscopic retrograde cholangiopancreatography (ERCP) in patients with autoimmune pancreatitis is diffuse or segmental attenuation of the main pancreatic duct (MPD), in contrast to the segmental stenoses often encountered with pancreatic adenocarcinoma. The other common findings are narrowing of the intrapancreatic portion of the common bile duct, irregular narrowing of extrahepatic bile ducts, and, less frequently, enlarged intrahepatic bile ducts [
Endoscopic ultrasonography (EUS) emerged as a particularly important pancreatic imaging tool due to its ability to provide high-resolution imaging along with short working distances for transluminal pancreatic interventions. Though nonspecific, most common finding on EUS is diffuse or focal pancreatic enlargement inhomogeneous echo pattern, stranding and calcification [
In summary, we further report another case of AIP that reemphasizes the importance and various strategies of distinguishing it from pancreatic adenocarcinoma in order to avoid unnecessary surgical intervention. The concept of a “great mimicker” may be invoked and a heightened vigilance of AIP in one’s differential diagnosis must be emphasized. As it is sometimes difficult to obtain adequate biopsy material from the pancreas, AIP is currently diagnosed based on careful consideration of a combination of characteristic clinical, serological, morphological, and histopathological features. More widespread use of pancreatic biopsy will aid in the diagnosis of autoimmune pancreatitis and provide a secure basis for the treatment with corticosteroids. Combined with a lack of prospectively validated clinical criteria that reliably establish the diagnosis, it is expected that the endoscopist will continue to play a central role in the diagnosis and management of AIP in the future.
Autoimmune pancreatitis
Main pancreatic duct
Common bile duct
Common hepatic duct
Lymphoplasmacytic sclerosing pancreatitis
Idiopathic duct-centric pancreatitis
Computer tomography
Magnetic resonance imaging
Magnetic resonance cholangiopancreatography
Endoscopic retrograde cholangiopancreatography
Endoscopic ultrasound-guided fine needle aspiration.
The authors declare that there is no conflict of interests regarding the publication of this paper.
Satya Allaparthi, Mohammed Sageer, and Mark J. Sterling reviewed, designed, edited, and organized the report; Mark J. Sterling served as the attending doctor for the patient and performed the ERCP; Satya Allaparthi performed the literature review and wrote the paper.