Figure 1
Autoimmune pancreatitis
Coronal CT of abdomen shows enlargement of the pancreas with sharp margin, minimal peripancreatic fat stranding and dilatation of the main pancreatic duct (< 5mm).
Autoimmune pancreatitis
SectionAbdominal imaging
Case TypeClinical Cases
AuthorsValbuena Durán, Emilio José; Gijón de la Santa, Luis; Pérez Retortillo, José Antonio
Connected authors
34 years, male
Clinical History
A 34-year-old male patient presented to the emergency room with three days of epigastric pain and nausea without fever. Laboratory examinations revealed elevated serum amylase and alkaline phosphatase.
He had a history of inflammatory bowel disease 2 years before.
He had a history of inflammatory bowel disease 2 years before.
Imaging Findings
Ultrasound examination revealed gallbladder acalculous and dilatation of the pancreatic duct without dilatation of the common bile duct.
The performed CT scan of the abdomen showed focal enlargement of the pancreas with loss of definition of pancreatic clefts, minimal peripancreatic fat stranding not extending into the mesentery or anterior pararenal fascia, peripancreatic lymph-nodes < 1 cm and mild dilatation of the main pancreatic duct at the level of the pancreatic body (Fig. 1).
MRI shows diffusion restriction with high DWI signal and low ADC signal (Fig. 3), minimally hyperintense with mild dilatation of the main pancreatic duct (< 5mm) in T2 weighted sequence (Fig. 2) and homogeneous enhancement on dynamic imaging, unidentified mass (Fig. 4).
Blood workup demonstrated elevated serum IgG4 levels.
The patient showed a favourable response to corticosteroid therapy.
The performed CT scan of the abdomen showed focal enlargement of the pancreas with loss of definition of pancreatic clefts, minimal peripancreatic fat stranding not extending into the mesentery or anterior pararenal fascia, peripancreatic lymph-nodes < 1 cm and mild dilatation of the main pancreatic duct at the level of the pancreatic body (Fig. 1).
MRI shows diffusion restriction with high DWI signal and low ADC signal (Fig. 3), minimally hyperintense with mild dilatation of the main pancreatic duct (< 5mm) in T2 weighted sequence (Fig. 2) and homogeneous enhancement on dynamic imaging, unidentified mass (Fig. 4).
Blood workup demonstrated elevated serum IgG4 levels.
The patient showed a favourable response to corticosteroid therapy.
Discussion
Autoimmune pancreatitis (AIP) is a distinct type of chronic pancreatitis (5-11%) and is characterized by infiltration of lymphocytes which leads to fibrosis and organ dysfunction [1-7].
Patients typically present abdominal pain (65%) or obstructive jaundice (52%)
There are 2 patterns of autoimmune pancreatitis [6]:
- Type 1 is more prevalent in Asian countries, with a peak of presentation to the sixth decade, with elevated serum IgG4 levels and often associated with the involvement of other organs (sclerosing cholangitis, kidneys, inflammatory bowel disease, retroperitoneal fibrosis, sclerosing sialadenitis...) Renal involvement is present in 35% and usually it manifests as multiple and bilateral renal lesions showing mild enhancement on delayed phase CT/MR.
- Type 2 is more common in Europe/US, affecting younger patients, not usually associated with elevation of IgG4 or involvement of other organs, although up to 25% have associated inflammatory bowel disease (especially ulcerative colitis)
The CT and MR appearance is variable depending on the pattern: diffuse or focal/multifocal enlargement of the pancreas with loss of the lobular contour, peripancreatic rim of low attenuation or hypointense "halo", pancreatic dilatation may be seen as can biliary dilatation in focal autoimmune pancreatitis located in the pancreatic head. At contrast-enhanced CT and MR imaging, mild decreased enhancement is seen in the early phase and moderate delayed enhancement is seen in the late phase. A hypointense halo with delayed enhancement is seen in 57%. The presence of a late homogeneous enhancement and ADC value <0.88 × 10-3 s / mm2 (AIP showing lower ADC values adenocarcinoma) would identify this entity with a sensitivity and specificity of 100% [4, 5, 7].
In Mayo Clinic criteria a diagnosis of autoimmune pancreatitis is made in patients with one or more of the following findings [2, 5]:
- histology findings
- characteristic CT/MR with elevate serum IgG4 levels
- response to steroid therapy
Autoimmune pancreatitis is an important mimic of pancreatic malignancy, in fact 2-6% of patients who undergo resection for a presumed tumour have autoimmune pancreatitis. However, there is no evidence that autoimmune pancreatitis predisposes to pancreatic carcinoma [1].
The treatment with steroids demonstrate dramatic response (within 4-6 weeks); the improvement of ductal stenosis is a specific finding of the AIP: not seen in any other type of chronic pancreatitis or pancreatic carcinoma. Pancreatic atrophy of the affected segments is observed after treatment [3, 5, 6].
However, disease recurrence is common (20-30%) after stopping corticosteroid therapy. It is much more frequent in the AIP type 1 and untreated patient [3, 6].
Patients typically present abdominal pain (65%) or obstructive jaundice (52%)
There are 2 patterns of autoimmune pancreatitis [6]:
- Type 1 is more prevalent in Asian countries, with a peak of presentation to the sixth decade, with elevated serum IgG4 levels and often associated with the involvement of other organs (sclerosing cholangitis, kidneys, inflammatory bowel disease, retroperitoneal fibrosis, sclerosing sialadenitis...) Renal involvement is present in 35% and usually it manifests as multiple and bilateral renal lesions showing mild enhancement on delayed phase CT/MR.
- Type 2 is more common in Europe/US, affecting younger patients, not usually associated with elevation of IgG4 or involvement of other organs, although up to 25% have associated inflammatory bowel disease (especially ulcerative colitis)
The CT and MR appearance is variable depending on the pattern: diffuse or focal/multifocal enlargement of the pancreas with loss of the lobular contour, peripancreatic rim of low attenuation or hypointense "halo", pancreatic dilatation may be seen as can biliary dilatation in focal autoimmune pancreatitis located in the pancreatic head. At contrast-enhanced CT and MR imaging, mild decreased enhancement is seen in the early phase and moderate delayed enhancement is seen in the late phase. A hypointense halo with delayed enhancement is seen in 57%. The presence of a late homogeneous enhancement and ADC value <0.88 × 10-3 s / mm2 (AIP showing lower ADC values adenocarcinoma) would identify this entity with a sensitivity and specificity of 100% [4, 5, 7].
In Mayo Clinic criteria a diagnosis of autoimmune pancreatitis is made in patients with one or more of the following findings [2, 5]:
- histology findings
- characteristic CT/MR with elevate serum IgG4 levels
- response to steroid therapy
Autoimmune pancreatitis is an important mimic of pancreatic malignancy, in fact 2-6% of patients who undergo resection for a presumed tumour have autoimmune pancreatitis. However, there is no evidence that autoimmune pancreatitis predisposes to pancreatic carcinoma [1].
The treatment with steroids demonstrate dramatic response (within 4-6 weeks); the improvement of ductal stenosis is a specific finding of the AIP: not seen in any other type of chronic pancreatitis or pancreatic carcinoma. Pancreatic atrophy of the affected segments is observed after treatment [3, 5, 6].
However, disease recurrence is common (20-30%) after stopping corticosteroid therapy. It is much more frequent in the AIP type 1 and untreated patient [3, 6].
Differential Diagnosis List
Autoimmune pancreatitis
Pancreatic carcinoma
Groove pancreatitis
Pancreatic lymphoma
Final Diagnosis
Autoimmune pancreatitis
References
[1] Takahashi N, Fletcjer JG, et al. (2009) Autoimmune pancreatitis: differentiation from pancreatic carcinoma and normal pancreas on the basis of enhancement characteristics at dual-phase CT. AJR Am J Roentgenol 193(2):479-484 (PMID: 19620446)
[2] Kim KP, Kim MH, et al. (2006) Diagnostic criteria for autoimmune chronic pancreatitis revisited. World J Gastroenterol 12(16): 2487-2496 (PMID: 16688792)
[3] Kamisawa T, Okam oto, et al (2007) Prognosis of autoimmune pancratitis. J Gastroenterol 42:59-62 (PMID: 17520225)
[4] Sahani DV et al (2004) Autoimmune pancreatitis: imaging features. Radiology 233(2): 345-352 (PMID: 15459324)
[5] Paraskevi A, Korosh Khalili, et al (2011) IgG4-related Sclerosing Disease: Autoimmune pancreatitis and extrapancreatic manifestations. Radiographics 31:1379-1402 (PMID: 21918050)
[6] López-Serrano A, Crespo J, Pascual I et al. (2016) Diagnosis, treatment and long-term outcomes of autoimmune pancreatitis in Spain based on the International Consensus Diagnostic Criteria: A multi-centre study. Pancreatology Epub ahead of print] (PMID: 26944001)
[7] Muhi A, Ichikawa T, Motosugi U, Sou H, Sano K, Tsuka- moto T, et al. (2012) Mass-forming autoimmune pancreatitis and pancreatic carcinoma: differential diagnosis on the basis of computed tomography and magnetic resonance cholangiopancreatography, and diffusion-weighted ima- ging findings. J Magn Reson Imaging 35:827-36 (PMID: 22069025)
Case information
| URL: | https://eurorad.org/case/13531 |
| DOI: | 10.1594/EURORAD/CASE.13531 |
| ISSN: | 1563-4086 |
License
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Figure 2
Autoimmune pancreatitis
T2 weighted sequence on axial plane: mild dilatation (< 5mm) of the main pancreatic duct at the level of the pancreatic body.
Figure 3
Autoimmune pancreatitis
DWI/ADC:
shows diffusion restriction with high DWI signal and low ADC signal (arrow).
Figure 4
Autoimmune pancreatitis
Contrast-enhanced T1-weighted MR images shows homogeneous enhancement of the entire gland, unidentified mass.
Autoimmune pancreatitis
Coronal CT of abdomen shows enlargement of the pancreas with sharp margin, minimal peripancreatic fat stranding and dilatation of the main pancreatic duct (< 5mm).
Department of Radiology University Hospital of Guadalajara Spain
Department of Radiology University Hospital of Guadalajara Spain
Autoimmune pancreatitis
T2 weighted sequence on axial plane: mild dilatation (< 5mm) of the main pancreatic duct at the level of the pancreatic body.
Department of Radiology University Hospital of Guadalajara Spain
Department of Radiology University Hospital of Guadalajara Spain
Autoimmune pancreatitis
DWI/ADC:
shows diffusion restriction with high DWI signal and low ADC signal (arrow).
Department of Radiology University Hospital of Guadalajara, Spain
Department of Radiology University Hospital of Guadalajara, Spain
Autoimmune pancreatitis
Contrast-enhanced T1-weighted MR images shows homogeneous enhancement of the entire gland, unidentified mass.
Department of Radiology University Hospital of Guadalajara, Spain
Department of Radiology University Hospital of Guadalajara, Spain