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01.12.2012 | Case report | Ausgabe 1/2012 Open Access

Journal of Medical Case Reports 1/2012

Autoimmune pancreatitis mimicking carcinoma of the head of the pancreas: a case report

Zeitschrift:
Journal of Medical Case Reports > Ausgabe 1/2012
Autoren:
Mohammad-Reza Ghadir, Farshad Sheikhesmaili, Fatemeh Attari, Reza Safdari, Amirhossein Ghanooni, Maryam Vaez-javadi
Wichtige Hinweise

Electronic supplementary material

The online version of this article (doi:10.​1186/​1752-1947-6-11) contains supplementary material, which is available to authorized users.

Competing interests

The authors declare that they have no competing interests.

Authors' contributions

GM conducted the first approach and examinations, participated in the treatment of our patient and oversaw the manuscript to publication. He was also responsible for final approval and supervision of the manuscript. SF and AF were involved in taking our patient's history and revising the manuscript. SR contributed to the writing and translation of the manuscript. GA contributed to the editing of the final manuscript. All authors read and approved the final manuscript.

Introduction

Autoimmune pancreatitis (AIP) is a rare disease and has only been reported in certain countries [1]. Cases of autoimmune pancreatitis that mimic pancreatic head cancer are rare in Iran.
AIP is a primary pancreatic disorder that is associated with other autoimmune disorders, such as primary biliary cirrhosis, rheumatoid arthritis, sarcoidosis, inflammatory bowel disease and vitiligo [2]. The disease commonly presents as recurrent mild abdominal pain with obstruction of the biliary ducts and pancreatic duct; there may be a pancreatic mass that can be misdiagnosed as pancreatic lymphoma or cancer [3]. Although such cases are rare, an accurate diagnosis of AIP can prevent the progression of the disease and unnecessary surgery.
The diagnostic criteria defined by the Mayo Clinic include one or more of three characteristics: diagnostic histology; related features in abdominal magnetic resonance imaging (MRI) or computed tomography (CT) in association with increased levels of immunoglobulin G4 (IgG4); and the response of intra- or extrapancreatic manifestations to corticosteroid therapy [4].
The imaging features of the disease have similar presentations in both MRI and CT scans and may include local or diffuse enlargement of the pancreas [5]. AIP can appear as a common bile duct stricture in an endoscopic retrograde cholangiopancreatography. It is impossible to distinguish AIP from pancreatic cancer solely by means of such imaging techniques [6].
A serum level of IgG4 above 135 ng/dL has very high sensitivity and specificity in differentiating AIP from pancreatic cancer [7]. However, although increased serum levels of IgG4 and radiologic features associated with a therapeutic response to corticosteroids are suggestive of AIP, a pancreatic biopsy is essential in confirming the diagnosis. Histological findings in the pancreatic sample include dense fibrosis and inflammatory levels of lymphoplasmacytic infiltration [4].

Case presentation

Our patient was a 75-year-old Iranian man, admitted to hospital with recurrent upper abdominal pain for the past 18 months. A common bile duct plastic stent had been inserted based on the results of diagnostic investigations, including an obstructive pattern of liver enzyme elevation, dilatation of extra- and intrahepatic bile ducts revealed through ultrasonography and heterogeneity of the pancreatic head (likely due to cancer) in an abdominal spiral CT scan with oral- and venous-contrast media (Figures 1 and 2). No abnormalities were found during a physical examination, with the exception of mild upper abdominal tenderness and vitiligo patches on his neck and hands (Tables 1 and 2).
Table 1
The results of laboratory tests before the stent placement.
Product
Level
Aspartate aminotransferase
110 U/L
Alanine aminotransferase
120 U/L
Alkaline phosphatase
540 IU
Total bilirubin
4.5 mg/dL
Direct bilirubin
2.5 mg/dL
Amylase
450 IU
Table 2
The laboratory test results after the stent placement.
Test
Level
Aspartate aminotransferase
21 U/L
Alanine aminotransferase
10 U/L
Alkaline phosphatase
250 IU
Total bilirubin
0.6 mg/dl
Direct bilirubin
0.2 mg/dl
Amylase
100 IU
White blood cell count
4100 cells/mm
Hemoglobin
311 g/dL
Mean corpuscular volume
76 fL
Erythrocyte sedimentation rate
36 mm/h
Blood urea nitrogen
18 mg/dL
Creatinine
1 mg/dL
Serum iron
25 mg/dL
Total iron binding capacity
468
Immunoglobulin G4
187 ng/mL
Carcinoembryonic antigen
2.7 ng/mL
Carbohydrate antigen 125
16 ng/mL
Carbohydrate antigen 19-9
8 ng/mL
Alpha fetoprotein
2.5 ng/5 mL
An upper gastrointestinal endoscopy, aimed at controlling the presence of occult blood in his stool, iron deficiency anemia and heartburn, showed lower esophageal ulcers associated with diaphragmatic herniation. A pathologic evaluation of the ulcer biopsy specimens confirmed reflux esophagitis. A colonoscopy was normal. Mild dilatation of his extra- and intrahepatic bile ducts was seen in repeated abdominal ultrasonography procedures. However, an endoscopic ultrasound showed a hypoechoic area, 2 cm in size, in the head of his pancreas. The pathological and cytological results of an aspiration biopsy of the lesion revealed fibrosis and inflammatory cell infiltration without evidence of malignancy (Figures 3 and 4).
Once AIP had been diagnosed, prednisolone was administered. Two months after treatment, a reevaluation of the pancreas head by means of an abdominal spiral CT scan with oral and venous contrast media did not show any abnormality, and the common bile duct stent was removed because of the positive therapeutic response.

Discussion

The etiology of AIP, a rare type of chronic pancreatitis, has been recognized by clinical, histological and morphologic findings [3]. Recently, it has been described as a systemic disease with lymphoplasmacytic infiltration that is associated with other autoimmune diseases. The disease has been reported in a number of countries and its incidence has been rising in some regions, especially in Japan [1, 6].
Typically, AIP can present in various clinical forms, including mild pancreatitis, acute recurrent pancreatitis, biliary duct strictures and pancreatitis, with such clinical presentations as primary sclerosing cholangitis and a pancreatic mass, which may be misdiagnosed as pancreatic cancer.
Acute AIP symptoms may also include rare, intermittent abdominal pain, weight loss, jaundice and an obstructive pattern of liver enzymes (an inappropriate rise of alkaline phosphatase relative to a mild elevation in aminotransferases) that may also be seen in cases of pancreatic cancer and cholangiocarcinoma [8].
AIP has been reported in two patients with obstructive jaundice and a diagnosis of pancreatic head cancer was made based on radiologic studies conducted by Japanese researchers [9]. In another study, AIP was reported as the most common benign disease in patients with a diagnosis of pancreatic adenocarcinoma who had undergone a pancreatoduodenectomy [10].
The definitive diagnosis of AIP is made by radiologic CT scan findings of a narrowing of the pancreatic duct and parenchymal edema of the pancreas [8]; and on MRI as a focal or diffuse expansion of the pancreas (a sausage shape). These findings are usually associated with an absence of vascular marking, calcification or fluid collection around the pancreas, a narrowing of the main pancreatic duct and a crescent development of the pancreas head [5].
AIP is routinely responsive to corticosteroid therapy over a one to four month period [7]. During treatment, patients typically have an immunological follow-up with an assessment of serum levels of IgG4 through a CT scan.

Conclusion

AIP is an autoimmune disease with varying diagnostic criteria, which include a range of pancreatic manifestations and specific MRI findings. A pancreatic biopsy, increased IgG4 serum level and a therapeutic response to corticosteroids are necessary in determining a definitive differentiation from a diagnosis of pancreatic adenocarcinoma based on radiologic findings [4]. A precise diagnosis of AIP would prevent complications arising from the progression of the disease and unnecessary surgery [4, 10].

Consent

Written consent was obtained from the patient for publication of this case report and any accompanying images.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://​creativecommons.​org/​licenses/​by/​2.​0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Competing interests

The authors declare that they have no competing interests.

Authors' contributions

GM conducted the first approach and examinations, participated in the treatment of our patient and oversaw the manuscript to publication. He was also responsible for final approval and supervision of the manuscript. SF and AF were involved in taking our patient's history and revising the manuscript. SR contributed to the writing and translation of the manuscript. GA contributed to the editing of the final manuscript. All authors read and approved the final manuscript.

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Zusatzmaterial
Authors’ original file for figure 1
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Authors’ original file for figure 2
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Authors’ original file for figure 3
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Authors’ original file for figure 4
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