Imaging Pearls ❯ Pancreas ❯ Autoimmune pancreatitis
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- “The pancreatic groove is a space surrounded by the pancreatic head, the duodenum, and the common bile duct. Pancreatic ductal adenocarcinoma arising in the groove area may not show typical signs, such as pancreatic cutoff, ductal obstruction, and upstream atrophy. The exact histopathologic origin of groove PDACs is unclear. Theory suggests that groove PDACs may arise from pancreatic tissue around the accessory pancreatic duct penetrating the groove and duodenum. Although the pancreatic tissue at this location is generally considered ectopic, in approximately 40% of cases it is continuous and/or closely related to the proper pancreas with the same morphologies and functions, suggesting that it may be a portion of the dorsal pancreas rather than an ectopic pancreas.”
Atypical and uncommon CT and MR imaging presentations of pancreatic ductal adenocarcinoma
Xu Hua Gong · Jian Rong Xu · Li Jun Qian
Abdominal Radiology (2021) 46:4226–4237 - “According to previous studies, the radiological findings, including a thickened duodenal wall (>3 mm), the presence of a cystic lesion in or near the pancreatic groove, no dilatation or dilatation of the common bile duct with distal tapering, focal and patchy enhancement rather than peripheral enhancement in the portal venous phase, and increased duodenal wall enhancement on MR imaging (relative to the proximal jejunal loops), favor the diagnosis of groove pancreatitis. Moreover, adenocarcinoma is much more likely to infiltrate posteriorly into the retroperitoneum and encase the vasculature.”
Atypical and uncommon CT and MR imaging presentations of pancreatic ductal adenocarcinoma
Xu Hua Gong · Jian Rong Xu · Li Jun Qian
Abdominal Radiology (2021) 46:4226–4237 - “Kalb et al. found that using all three features (i.e., focal thickening of the second portion of the duodenum wall, abnormal enhancement of the second portion of the duodenum, and cystic focus in the expected region of the accessory pancreatic duct) achieved an accuracy of 87.2% in distinguishing groove pancreatitis from carcinoma. However, there is still considerable overlap in the imaging manifestations of the two entities. Distinction can be extremely difficult when there are no cystic lesions within the mass and in the presence of a thickened duodenal wall.”
Atypical and uncommon CT and MR imaging presentations of pancreatic ductal adenocarcinoma
Xu Hua Gong · Jian Rong Xu · Li Jun Qian
Abdominal Radiology (2021) 46:4226–4237 - “Pancreatic ductal adenocarcinomas (PDACs) occasionally have atypical and uncommon imaging presentations that can present a diagnostic dilemma and result in false interpretation. This article aimed to illustrate these CT and MR imaging findings, including isoattenuating PDAC, coexisting acute pancreatitis, PDAC with a cystic feature, groove PDAC, diffuse PDAC, hypointensity on diffusion-weighted imaging (DWI), multifocal PDAC, intratumoral calcification, and extrapancreatic invasion with a barely discernable mass. A subset of PDACs with atypical features are occasionally encountered during routine clinical practice. Knowledge of and attention to these atypical and uncommon variable imaging features may allow radiologists to avoid misinterpretation and a delayed diagnosis.”
Atypical and uncommon CT and MR imaging presentations of pancreatic ductal adenocarcinoma
Xu Hua Gong · Jian Rong Xu · Li Jun Qian
Abdominal Radiology (2021) 46:4226–4237 - “Primary pancreatic lymphoma (PPL) is a very rare disease, representing only 0.1% of malignant lymphomas and 0.2% of primary pancreatic tumours. The World Health Organization provides precise diagnostic criteria: the bulk of the disease is localized in the pancreas; adjacent lymph node involvement and distant spread may exist but the primary clinical presentation has to involve the pancreatic gland. The disease can develop at any age, but usually affects elderly patients, with higher incidence in males. Clinical presentation is variable: in most cases the first manifestation is abdominal pain; other clinical findings include systemic symptoms such as fever, night sweats and weight loss. Jaundice and/or gastric or duodenal obstruction may be present.”
CT imaging of primary pancreatic lymphoma: experience from three referral centres for pancreatic diseases
Enrico Boninsegna et al.
Insights Imaging. 2018 Feb; 9(1): 17–24.
- Purpose: The purpose of this study was to determine whether computed tomography (CT)-based machine learning of radiomics features could help distinguish autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC).
Results: The pancreas was diffusely involved in 37 (37/89; 41.6%) patients with AIP and not diffusely in 52(52/89; 58.4%) patients. Using machine learning, 95.2% (59/62; 95% confidence interval [CI]: 89.8–100%),83.9% (52:67; 95% CI: 74.7–93.0%) and 77.4% (48/62; 95% CI: 67.0–87.8%) of the 62 test patients werecorrectly classified as either having PDAC or AIP with thin-slice venous phase, thin-slice arterial phase, and thick-slice venous phase CT, respectively. Three of the 29 patients with AIP (3/29; 10.3%) were incorrectly classified as having PDAC but all 33 patients with PDAC (33/33; 100%) were correctly classified with thin-slice venous phase with 89.7% sensitivity (26/29; 95% CI: 78.6–100%) and 100% specificity (33/33;95% CI: 93–100%) for the diagnosis of AIP, 95.2% accuracy (59/62; 95% CI: 89.8–100%) and area under the curve of 0.975 (95% CI: 0.936–1.0).
Conclusions: Radiomic features help differentiate AIP from PDAC with an overall accuracy of 95.2%. - Purpose: The purpose of this study was to determine whether computed tomography (CT)-based machine learning of radiomics features could help distinguish autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC).
Conclusions: Radiomic features help differentiate AIP from PDAC with an overall accuracy of 95.2%.
Differentiating autoimmune pancreatitis from pancreatic ductal adenocarcinoma with CT radiomics features
S. Park, L.C. Chu, R.H. Hruban, Vogelstein, K.W. Kinzler, A.L. Yuille, Fouladi, S. Shayesteh, S. Ghandili, C.L. Wolfgang, R. Burkhart, J. He, E.K. Fishman, S. Kawamoto
Diagnostic and Interventional Imaging (in press) - •CT radiomics differentiates AIP from PDAC with 89.7% sensitivity and 100% specificity.
•Thin slice CT radiomics better differentiates AIP from PDAC than thick slice CT radiomics.
•Venous phase CT radiomics better differentiates AIP from PDAC than arterial phase radiomics.
Differentiating autoimmune pancreatitis from pancreatic ductal adenocarcinoma with CT radiomics features
S. Park, L.C. Chu, R.H. Hruban, Vogelstein, K.W. Kinzler, A.L. Yuille, Fouladi, S. Shayesteh, S. Ghandili, C.L. Wolfgang, R. Burkhart, J. He, E.K. Fishman, S. Kawamoto
Diagnostic and Interventional Imaging (in press) - “AIP has clinical and imaging features that overlap with those of pancreatic ductal adenocarcinoma (PDAC) and can pose a significant diagnostic dilemma even for experienced radiologists . The management of these two conditions is markedly different. Patients with AIP are initially treated with oral corticosteroids, while patients with PDAC are treated with a combination of surgical resection and chemotherapy. The most common presentation of AIP is obstructive jaundice and pancreatic enlargement, which mimics that of PDAC and 2–6% of patients undergoing surgical resection for suspected pancreatic cancer are actually diagnosed with AIP upon histopathological analysis. Computed tomography (CT) plays an important role in the evaluation of suspected pancreatic cancer, and is often the initial diagnostic imaging modality. It is of utmost importance to correctly differentiate AIP from PDAC early in the disease process so as to administer the proper treatment and avoid unnecessary pancreatic resections in patients with AIP.”
Differentiating autoimmune pancreatitis from pancreatic ductal adenocarcinoma with CT radiomics features
S. Park, L.C. Chu, R.H. Hruban, Vogelstein, K.W. Kinzler, A.L. Yuille, Fouladi, S. Shayesteh, S. Ghandili, C.L. Wolfgang, R. Burkhart, J. He, E.K. Fishman, S. Kawamoto
Diagnostic and Interventional Imaging (in press) 
Differentiating autoimmune pancreatitis from pancreatic ductal adenocarcinoma with CT radiomics features
S. Park, L.C. Chu, R.H. Hruban, Vogelstein, K.W. Kinzler, A.L. Yuille, Fouladi, S. Shayesteh, S. Ghandili, C.L. Wolfgang, R. Burkhart, J. He, E.K. Fishman, S. Kawamoto
Diagnostic and Interventional Imaging (in press)- "In conclusion, radiomics analysis of CT images is reasonably accurate in differentiating AIP from PDAC. Using such features, in combination with clinical and standard radiologic analyses, may improve the accuracy of AID diagnosis and spare patients’ unnecessary surgical procedure.”
Differentiating autoimmune pancreatitis from pancreatic ductal adenocarcinoma with CT radiomics features
S. Park, L.C. Chu, R.H. Hruban, Vogelstein, K.W. Kinzler, A.L. Yuille, Fouladi, S. Shayesteh, S. Ghandili, C.L. Wolfgang, R. Burkhart, J. He, E.K. Fishman, S. Kawamoto
Diagnostic and Interventional Imaging (in press) - "Our results showed that by combining radiomics features, AIP could be distinguished from PDAC with a sensitivity of 89.7% and a specificity of 100%, and an overall accuracy of 95.2%. Among 3 patients with focal AIP were falsely classified as PDAC using radiomics features, two patients had focal AIP in the head with a plastic stent in the common bile duct, which can sensitively affect to the quantitative feature computation. In our study, the accuracy was higher than that in a previous study that evaluated CT to differentiate AIP from PDAC based on morphological features. In that study, the mean accuracies for diagnosing AIP and PDAC were 68% and 83%, respectively. In our study, AIP was considered as a diagnosis or differential diagnosis by the radiologists in only in 67% of patients with AIP not already suspected to be AIP at the time of CT examination.”
Differentiating autoimmune pancreatitis from pancreatic ductal adenocarcinoma with CT radiomics features
S. Park, L.C. Chu, R.H. Hruban, Vogelstein, K.W. Kinzler, A.L. Yuille, Fouladi, S. Shayesteh, S. Ghandili, C.L. Wolfgang, R. Burkhart, J. He, E.K. Fishman, S. Kawamoto
Diagnostic and Interventional Imaging (in press) - “We found that radiomics features were better at distinguishing AIP from PDAC using venous phase CT images than using arterial phase images. We also performed radiomics analysis on both thin- and thick-slice reconstructions. We found that thin-slice CT based radiomics signature had better diagnostic performance than thick-slice, as reported in pulmonary nodules and lung cancer in prior studies.”
Differentiating autoimmune pancreatitis from pancreatic ductal adenocarcinoma with CT radiomics features
S. Park, L.C. Chu, R.H. Hruban, Vogelstein, K.W. Kinzler, A.L. Yuille, Fouladi, S. Shayesteh, S. Ghandili, C.L. Wolfgang, R. Burkhart, J. He, E.K. Fishman, S. Kawamoto
Diagnostic and Interventional Imaging (in press)
- "Type I AIP is associated with high serum IgG4 levels; however, high serum IgG4 levels can also be seen in 7–10% of PDAC. It was reported that an IgG4 level greater than 135 mg/dL can differentiate autoimmune pancreatitis from PDAC with 95% sensitivity and 97% specificity. On the other hand, type II AIP is often associated with normal serum IgG4 level.”
Pancreatitis and PDAC: association and differentiation
Sherif B. Elsherif et al.
Abdominal Radiology 2019 (in press) https://doi.org/10.1007/s00261-019-02292-w - "In conclusion, differentiating pancreatic cancer from mass- forming chronic pancreatitis remains a major and primary problem in the imaging and management of pancreatic masses. There is an overlap between MFCP and PDAC on imaging for multiple modalities, but certain imaging features such as enhancement pattern/perfusion on contrast-enhanced studies, iodine content on spectral CT, main pancreatic duct findings such as the duct-penetrating sign and double-duct sign on MRCP, and ADC value on DWI may be able to suggest pancreatic cancer versus chronic pancreatitis as the likely diagnosis. Overall, biopsy is currently still necessary to establish the diagnosis. These advances in imaging nev- ertheless do show promise for developing in the future a non-invasive approach in differentiating these two entities.”
Pancreatitis and PDAC: association and differentiation
Sherif B. Elsherif et al.
Abdominal Radiology 2019 (in press) https://doi.org/10.1007/s00261-019-02292-w
- “Type 1 auto- immune pancreatitis demonstrates elevated levels of serum IgG4 and is associated with IgG4-related disease involving other organs besides the pancreas. The diagnostic feature of Type 2 is extensive infiltration of the pancreatic ductal epithelium by neutrophils known as granulocyte epithelial lesion (GEL) on histopathological analysis. Type 1 AIP has a higher incidence in older males and those from Asia, while type 2 AIP favors younger patients in the United States and Europe without a clear gender predilection. Both types tend to respond to corticosteroids, however type 1 more commonly relapses (ranging from 30 to 60% of patients). Furthermore, the two types cannot be easily differentiated radiographically. Type 1 is more often associated with other organ involvement.”
Inflammatory mimickers of pancreatic adenocarcinoma
Kunal Kothar ET AL.
Abdominal Radiology (In Press, 2019) https://doi.org/10.1007/s00261-019-02233-7 - Mass-forming autoimmune pancreatitis accounts for approximately 33 to 41% of all cases of autoimmune pancreatitis. It is important to distinguish this process from pancreatic adenocarcinoma to avoid potentially unnecessary surgical intervention in patients with autoimmune pancreatitis. Kamisawa et al. reported that approximately 19% of patients with autoimmune pancreatitis had surgery because they were misdiagnosed as having pancreatic or bile duct cancer.”
Inflammatory mimickers of pancreatic adenocarcinoma
Kunal Kothar ET AL.
Abdominal Radiology (In Press, 2019) https://doi.org/10.1007/s00261-019-02233-7 - “The presence of extrapancreatic manifestations of autoimmune pancreatitis are important to identify as they can suggest that a pancreatic mass may represent autoimmune pancreatitis. Renal involvement includes small peripheral cortical nodules, round lesions, well-defined wedge-shaped lesions or diffuse patchy involvement. Biliary involvement, retroperitoneal fibrosis, periaortitis and other features of IgG4-related systemic disease and improvement of imaging findings following treatment with corticosteroids suggests autoimmune pancreatitis.”
Inflammatory mimickers of pancreatic adenocarcinoma
Kunal Kothar ET AL.
Abdominal Radiology (In Press, 2019) https://doi.org/10.1007/s00261-019-02233-7
- “Autoimmune pancreatitis (AIP) is an uncommon form of chronic pancreatitis caused by an autoimmune mechanism. It is a challenge to distinguish focal AIP from PDAC because the two diseases show similar imaging features, but several reports have offered suggestions for discriminating between them. According to those studies, slightly lower or similar signal intensity compared with the spleen on unenhanced T1-weighted images, relatively homogeneous enhancement, signs of pancreatic duct penetration, smooth tapered narrowing of the pancreatic duct (icicle sign) or bile duct, multifocal stricture of the pancreatic duct, and a delayed enhancement pattern on dynamic enhanced images are features favoring AIP over PDAC.”
Pancreas Ductal Adenocarcinoma and its Mimics: Review of Cross- sectional Imaging Findings for Differential Diagnosis.
Kim, SS, et al.
Journal of the Belgian Society of Radiology. 2018; 102(1): 71, 1–8.
- “The advent of the ICDC guidelines in 2011 represents the most current comprehensive guidelines for use in the diagnosis of AIP. The ICDC, similar to the preceding guidelines, cited the 5 cardinal features of AIP and drew on evidence from each of those features in the diagnosis of AIP. Other than histologic confirmation, the use of evidence from a single cardinal feature should not be used in isolation and instead should be paired with other evidence as outlined by ICDC in the diagnosis of AIP.”
Autoimmune Pancreatitis : An Update on Diagnosis and Management Kamraan Madhani, James J. Farrell Gastroenterology Clinics of North America Volume 45, Issue 1, March 2016, Pages 29–43 - “AIP was initially recognized as a disease associated with characteristic clinical, radiologic, and serologic features affecting primarily the pancreas, with the ability to involve other organs. However, more recently AIP has been associated with other immune-mediated diseases, including immunoglobulin (Ig) G4–associated cholangitis (IAC), salivary gland disorders, mediastinal fibrosis, retroperitoneal fibrosis, tubulointerstitial disease and inflammatory bowel disease, and increased levels of IgG4, both in tissue plasma cells and in the serum,thus terming this collection of disease processes IgG4-related systemic disease.”
Autoimmune Pancreatitis : An Update on Diagnosis and Management Kamraan Madhani, James J. Farrell Gastroenterology Clinics of North America Volume 45, Issue 1, March 2016, Pages 29–43 - “A recent prospective study compared 32 patients with AIP with a control population of patients with pancreatic adenocarcinoma based on CT imaging features. Independently, 3 radiologists read the images and reported common features seen in each disease. The most common findings seen on CT in patients with AIP were common bile duct (CBD) stricture (63%), bile duct wall hyperenhancement (47%), and diffuse parenchymal enlargement (41%).”
Autoimmune Pancreatitis : An Update on Diagnosis and Management Kamraan Madhani, James J. Farrell Gastroenterology Clinics of North America Volume 45, Issue 1, March 2016, Pages 29–43
- “The purposes of this study were to identify the most common imaging features of autoimmune pancreatitis and to evaluate the utility of MDCT for differentiating autoimmune pancreatitis from two more frequently encountered differential diagnoses-pancreatic ductal adenocarcinoma and acute interstitial pancreatitis.”
Use of MDCT to Differentiate Autoimmune Pancreatitis From Ductal Adenocarcinoma and Interstitial Pancreatitis. Lee-Felker SA et al. AJR Am J Roentgenol. 2015 Jul;205(1):2-9. - “The most common imaging features of autoimmune pancreatitis were sausage shape (25/39 [64%]) and low-attenuation halo (23/39 [59%]). Pancreatic duct dilatation (20/25 [80%]) and biliary dilatation (11/25 [44%]) were most frequent in pancreatic ductal adenocarcinoma. Peripancreatic stranding (22/27 [81%]) was most frequent in acute interstitial pancreatitis.”
Use of MDCT to Differentiate Autoimmune Pancreatitis From Ductal Adenocarcinoma and Interstitial Pancreatitis. Lee-Felker SA et al. AJR Am J Roentgenol. 2015 Jul;205(1):2-9. - “Sausage shape, low-attenuation halo, and absence of a pancreatic duct or biliary dilatation differentiated autoimmune pancreatitis from pancreatic ductal adenocarcinoma with an accuracy of 0.88. Sausage shape and absence of peripancreatic stranding differentiated autoimmune pancreatitis from acute interstitial pancreatitis with an accuracy of 0.82.”
Use of MDCT to Differentiate Autoimmune Pancreatitis From Ductal Adenocarcinoma and Interstitial Pancreatitis. Lee-Felker SA et al. AJR Am J Roentgenol. 2015 Jul;205(1):2-9. - “Typical cases of autoimmune pancreatitis can be accurately differentiated from pancreatic ductal adenocarcinoma and acute interstitial pancreatitis on the basis of characteristic MDCT features. However, autoimmune pancreatitis should be considered in the presence of atypical features.”
Use of MDCT to Differentiate Autoimmune Pancreatitis From Ductal Adenocarcinoma and Interstitial Pancreatitis. Lee-Felker SA et al. AJR Am J Roentgenol. 2015 Jul;205(1):2-9.
- “Pitfalls leading to major pancreatic resections in autoimmune pancreatitis include unnecessarily high thresholds for initiating serum IgG4 evaluation, false positive cytologic evaluations for malignancy, and failure to recognize non-classic initial presentations, or recurrence of disease. Better diagnostic strategies are needed, but awareness of these specific findings should help to decrease the number of patients undergoing operation for unrecognized autoimmune pancreatitis.”
Pitfalls in avoiding operation for autoimmune pancreatitis
Learn PA et al.
Surgery 2011 Nov;150(5):968-74
- “ In rare instances, IgG4-related sclerosing disease manifests atypical features in various organs in the abdomen. It is important that radiologists be aware of the typical and atypical features of this disease to provide timely effective treatment.”
Atypical Manifestations of IgG4-Related Sclerosing Disease in the Abdomen: Imaging Findings and Pathologic Correlations
Kim JH et al.
AJR 2013; 200:102-112 - “ IgG4 related sclerosing disease is a systemic disease characterized by extensive infiltration of IgG4-positive plasma cells and lymphocytes in various organs; it responds well to steroid therapy.”
Atypical Manifestations of IgG4-Related Sclerosing Disease in the Abdomen: Imaging Findings and Pathologic Correlations
Kim JH et al.
AJR 2013; 200:102-112 - “ The organ most commonly involved in IgG4 related sclerosing disease is the pancreas, and such involvement is termed autoimmune pancreatitis. Various extrapancreatic organs, including the bile ducts, liver, gallbladder, kidneys, retroperitoneum, gastrointestinal tract, mesentery, prostate, lungs, lacrimal and salivary glands, and lymph nodes, can be involved with AIP either synchronously or metachronously, and in rare cases there can be extrapancreatic involvement without any sign of AIP.”
Atypical Manifestations of IgG4-Related Sclerosing Disease in the Abdomen: Imaging Findings and Pathologic Correlations
Kim JH et al.
AJR 2013; 200:102-112 - “Various extrapancreatic organs, including the bile ducts, liver, gallbladder, kidneys, retroperitoneum, gastrointestinal tract, mesentery, prostate, lungs, lacrimal and salivary glands, and lymph nodes, can be involved with AIP either synchronously or metachronously, and in rare cases there can be extrapancreatic involvement without any sign of AIP.”
Atypical Manifestations of IgG4-Related Sclerosing Disease in the Abdomen: Imaging Findings and Pathologic Correlations
Kim JH et al.
AJR 2013; 200:102-112 - Autoimmune Pancreatitis: Facts
- Diffuse sausagelike swelling of the pancreas with loss of pancreatic clefts
- Symmetric capsule like rim of low attenuation surrounding the pancreas
- Multifocal irregular narrowing of the main pancreatic duct without downstream narrowing
- Associated renal involvement and retroperitoneal fibrosis is common - “Focal involvement of the pancreas, focal autoimmune pancreatitis (AIP), has been reported to have an incidence that ranges from 28% to 41%. The image findings of focal AIP can mimic those of pancreatic cancer.”
Atypical Manifestations of IgG4-Related Sclerosing Disease in the Abdomen: Imaging Findings and Pathologic Correlations
Kim JH et al.
AJR 2013; 200:102-112 - IgG4-Related Sclerosing Disease: Rare Extrapancreatic Findings
- Renal lesions (range from well defined nodules as well as patchy enhancement)
- Retroperitoneal fibrosis
- Pseudocysts in the spleen
- Hepatic focal mass
- Gastric focal mass
- Omental infiltration
- Sclerosing mesenteritis
- Vas deferens mass
- Autoimmune Pancreatitis
1. Diffuse enlargement of the pancreas
- Rarely focal
2. Diffuse or segmental narrowing of the PD
3. Minimal peripancreatic stranding
4. Low attenuation capsule-like rim
- May show delayed enhancement
5. Strictures of CBD
- Thickening and enhancement - Automimmune Pancreatitis
Extrapancreatic Findings:
1. Retroperitoneal Fibrosis
2. Salivary gland enlargement
3. Renal involvement
- Renal infarcts or discrete renal parenchymal lesions
4. Lung disease (reticular nodules or ground-glass)
5. Mediastinal adenopathy