**4.3 Images**

Radiologic exams, CT scan, and MR are the bases of the diagnosis in the everyday clinical practice [22]. Typical sausage-like increase in pancreatic size with a peripheral halo is seen in several cases when the pancreas is diffusely affected. Frequently, only segments of pancreas are involved. In these cases the differences in density or signal intensity as compared to the normal segments (**Figures 1b, 2b** and **3a,b**), the late enhancement with contrast, and the irregular stricture of the main pancreatic duct can be helpful. In the difficult situation when there is a clinical suspicion of pancreatic cancer, even without a clear-cut mass, the absence of significant upstream duct dilation is an important element which

#### **Figure 1.**

*(a) Magnetic resonance cholangiography showing pancreatic duct stricture in the head and stenosis of intrapancreatic segment of choledochus with proximal dilatation. Pancreatic duct is only slightly dilated in the body and tail. (b) Pancreatic head is enlarged with slightly hyperintense signal in T2. The pancreatic duct is only seen in the body and tail. (c and d) The same patient and same images after 2 months of treatment. Almost complete recovery, with slight pancreatic atrophy. The images of this chapter come from the Radiolology Department of Clinical Hospital of University of Chile and are the authors' property.*

**97**

types 1 and 2 of AIP.

**Figure 2.**

**Figure 3.**

*involved segments.*

*Autoimmune Pancreatitis: Clinical Presentation and Therapy*

*in the augmented pancreatic head, but the upstream dilatation is only mild.*

helps to distinguish the two pathologies with diametrically different prognoses (**Figures 1a,b, 2a,b** and **5a**). It is noteworthy that neither necrosis nor major peripancreatic fluid collection are seen in AIP. Sometimes, pseudocysts can complicate the disease [23]; they also respond to steroids and can disappear even completely. It is important to emphasize that there is no difference in the radiologic alterations in

*Focal AIP in the pancreatic tail. (a) T2, hyperintensity of the signal; (b) T1, hypointense signal. Arrow: the swollen pancreatic segment. Pointed arrow: normal pancreas. Note the clear limitation between the normal and* 

*(a) Markedly dilated choledochus, proximal to the stenotic intrapancreatic segment of the bile duct. Irregular multiple stenosis of the main pancreatic duct. (b) Again, the structured pancreatic duct is practically not seen* 

The necessity of ERCP in order to establish the diagnosis of AIP nowadays is an exception. Magnetic resonance images have a similar sensibility in the diagnosis. If performed, irregular and usually multifocal narrowing of the main pancreatic duct is seen in the affected pancreatic segment, without an important upstream dilatation (**Figure 5a**). Stenosis of intrapancreatic segment of choledochus is frequent, and, sometimes, irregular strictures of extra- and intrahepatic bile ducts can show the associated IgG4-related cholangitis, very similar to the primary sclerosing cholangitis (PSC) (**Figures 5b** and **6a**). The clinical need of ERCP is determined in the majority of the cases by the severe obstructive jaundice and the intention to drain the obstructed dilated bile duct with a biliary endoprosthesis (**Figures 5b** and **6b**). However, it is at least a matter of discussion: the decrease in bilirubin level in response to steroid treatment is strikingly rapid, and it seems better to avoid unnecessary instrumentalization of biliary tract with the risk of bacterial contamination. Once ERCP is performed without the previous suspicion of AIP and contrast material injected in the obstructed bile duct, stent placement is mandatory as in any other causes of bile duct obstruction. In our practice, we performed ERCP only in our first

*4.3.1 When to perform diagnostic ERCP and biliary drainage?*

*DOI: http://dx.doi.org/10.5772/intechopen.83349*

*Autoimmune Pancreatitis: Clinical Presentation and Therapy DOI: http://dx.doi.org/10.5772/intechopen.83349*

#### **Figure 2.**

*Chronic Autoimmune Epithelitis - Sjogren's Syndrome and Other Autoimmune Diseases...*

autoimmunity is not a frequent cause of recurrent acute pancreatitis.

**4.2 Serology**

ing it.

**4.3 Images**

segment of choledochus by the fibroinflammatory process in the pancreatic head. Unfortunately, it shares typical symptoms of pancreatic head cancer and represents one of the most challenging difficulties in differential diagnosis. Abdominal pain and mild acute pancreatitis are also important manifestations. However, severe acute pancreatitis and major local fluid collections practically do not occur and

As described above, the only valuable serological marker is the serum IgG4 level [17]. However, its performance in the diagnosis is variable: it can be increased only in type 1, not in type 2. Other unspecific autoantibodies have low sensibility in AIP and are not used routinely. Sometimes, IgE and peripheral eosinophils can be increased. If altered, they help in the diagnosis; if not, they have no value in exclud-

Radiologic exams, CT scan, and MR are the bases of the diagnosis in the everyday clinical practice [22]. Typical sausage-like increase in pancreatic size with a peripheral halo is seen in several cases when the pancreas is diffusely affected. Frequently, only segments of pancreas are involved. In these cases the differences in density or signal intensity as compared to the normal segments (**Figures 1b, 2b** and **3a,b**), the late enhancement with contrast, and the irregular stricture of the main pancreatic duct can be helpful. In the difficult situation when there is a clinical suspicion of pancreatic cancer, even without a clear-cut mass, the absence of significant upstream duct dilation is an important element which

*(a) Magnetic resonance cholangiography showing pancreatic duct stricture in the head and stenosis of intrapancreatic segment of choledochus with proximal dilatation. Pancreatic duct is only slightly dilated in the body and tail. (b) Pancreatic head is enlarged with slightly hyperintense signal in T2. The pancreatic duct is only seen in the body and tail. (c and d) The same patient and same images after 2 months of treatment. Almost complete recovery, with slight pancreatic atrophy. The images of this chapter come from the Radiolology* 

*Department of Clinical Hospital of University of Chile and are the authors' property.*

**96**

**Figure 1.**

*(a) Markedly dilated choledochus, proximal to the stenotic intrapancreatic segment of the bile duct. Irregular multiple stenosis of the main pancreatic duct. (b) Again, the structured pancreatic duct is practically not seen in the augmented pancreatic head, but the upstream dilatation is only mild.*

#### **Figure 3.**

*Focal AIP in the pancreatic tail. (a) T2, hyperintensity of the signal; (b) T1, hypointense signal. Arrow: the swollen pancreatic segment. Pointed arrow: normal pancreas. Note the clear limitation between the normal and involved segments.*

helps to distinguish the two pathologies with diametrically different prognoses (**Figures 1a,b, 2a,b** and **5a**). It is noteworthy that neither necrosis nor major peripancreatic fluid collection are seen in AIP. Sometimes, pseudocysts can complicate the disease [23]; they also respond to steroids and can disappear even completely. It is important to emphasize that there is no difference in the radiologic alterations in types 1 and 2 of AIP.

#### *4.3.1 When to perform diagnostic ERCP and biliary drainage?*

The necessity of ERCP in order to establish the diagnosis of AIP nowadays is an exception. Magnetic resonance images have a similar sensibility in the diagnosis. If performed, irregular and usually multifocal narrowing of the main pancreatic duct is seen in the affected pancreatic segment, without an important upstream dilatation (**Figure 5a**). Stenosis of intrapancreatic segment of choledochus is frequent, and, sometimes, irregular strictures of extra- and intrahepatic bile ducts can show the associated IgG4-related cholangitis, very similar to the primary sclerosing cholangitis (PSC) (**Figures 5b** and **6a**). The clinical need of ERCP is determined in the majority of the cases by the severe obstructive jaundice and the intention to drain the obstructed dilated bile duct with a biliary endoprosthesis (**Figures 5b** and **6b**). However, it is at least a matter of discussion: the decrease in bilirubin level in response to steroid treatment is strikingly rapid, and it seems better to avoid unnecessary instrumentalization of biliary tract with the risk of bacterial contamination. Once ERCP is performed without the previous suspicion of AIP and contrast material injected in the obstructed bile duct, stent placement is mandatory as in any other causes of bile duct obstruction. In our practice, we performed ERCP only in our first

patients, later on only in some exceptional cases when even concomitant sclerosing cholangitis was not excluded, and it was impossible to avoid biliary stent placement. In fact, Chari's group published the same tendency from Mayo Clinic [24].
