**4.6 Response to glucocorticosteroid treatment**

The improvement in the pancreatic morphology in response to steroid treatment is very quick, easily detectable already after 2 weeks. This fact can be used even in the differential diagnosis: while AIP improves rapidly, pancreatic cancer evidently does not respond to steroids, and no change in the pancreatic morphology can be observed after 2 weeks. In addition, it was demonstrated by Moon et al. [29] that the "lost" 2 weeks did not change the resectability of the malignant lesion. This short treatment trial is only acceptable if a good biopsy is not available or the histologic finding is uncertain in a patient of high surgical risk. It means that steroid treatment trial has to be restricted to the cases, when:


In conclusion, in the everyday clinical practice, the basis of the diagnosis is radiology, showing typical characteristic images of the pancreas (**Table 2**). However, differential diagnosis is not always easy and other parameters could be of utility. Unfortunately, no specific autoantibodies have been discovered till now. Increased, >270 mg/dl serum IgG4 level seems to be quite specific but not enough sensitive in the diagnosis of type 1 AIP, and IgG4 has no value in type 2. Other organ involvement can be useful again in the diagnosis of type 1 AIP. In addition, imaging alterations do not distinguish between type 1 and type 2. Thus, type 2 AIP almost always requires biopsy and histology; in its absence the diagnosis can be only highly probable but not definitive [30]. Type 1 AIP can be definitely demonstrated without biopsy in the majority of cases. However, several patients have an undetermined AIP, which is named NOS [31], a mixture of seronegative type 1 and possible type 2 cases. A useful simple algorithm in the differential diagnosis is proposed in **Figure 7**.

After the diagnosis of AIP, the classification has practical and prognostic significance. As described above, characteristic image on MRI associated with serum IgG4 level more than double of upper limit of normal (>270 mg%) and/ or simultaneous or sometimes previous presence of IgG4-related disease in other organs are sufficient to establish definitive diagnosis of type 1 AIP, even without histology. If IgG4 is normal and the only associated disease is ulcerative colitis or Crohn's disease, the classification in type 2 AIP is probable, but not definitive. If the patient does not have any associated disease, only NOS AIP is the clinically


*Note the unique combination of findings in autoimmune pancreatitis. The absence of more significant upstream dilatation of pancreatic duct and altered signal in the parenchyma, both useful as compared to pancreatic cancer. On the other hand, the absence of necrosis and peripancreatic fluid collections helps to distinguish it as compared to acute pancreatitis.*

#### **Table 2.**

*Characteristic alterations in pancreatic and peripancreatic morphology, useful in the differential diagnosis.*

**101**

**Figure 8.**

**Figure 7.**

*Autoimmune Pancreatitis: Clinical Presentation and Therapy*

*A simplified algorithm for the differential diagnosis and treatment of autoimmune pancreatitis. Briefly: Once AIP is suspected on the basis of medical history or abdominal US findings, CT scan or MRI is performed, of course completed with determination of the IgG4 level in the serum. These data can be sufficient to establish definitive diagnosis of AIP or pancreatic cancer and initiate proper treatment. The effect of steroid treatment must be confirmed after a short time, about 2 weeks: if no improvement is detectable, the diagnosis of AIP is improbable, and the patients must be reevaluated for surgery or at least biopsy. If the initial workup gives an equivocal result, EUS and biopsy (not cytology!) is necessary to define the diagnosis and treatment. CT, computed tomography; MRI, magnetic resonance imaging; EUS, endosonography; Cht, chemotherapy.*

*Classification of AIP in different subclasses. Type 1 can be frequently demonstrated without histology, while definitive diagnosis of type 2 requires biopsy in the majority of cases. NOS is clinically a useful category, in particular, when no biopsy is available. For details, see text. LPSP, lymphoplasmacytic sclerosing pancreatitis; GEL, granulocytic epithelial lesion; NOS, Not Otherwise Specified; IBD, inflammatory bowel disease.*

*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 7.**

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

• EUS and pancreatic biopsy is not available or its result is uncertain.

• The patient is known and followed by a multidisciplinary group.

• If there is no clear improvement after 2 weeks of treatment, steroids are

In conclusion, in the everyday clinical practice, the basis of the diagnosis is radiology, showing typical characteristic images of the pancreas (**Table 2**). However, differential diagnosis is not always easy and other parameters could be of utility. Unfortunately, no specific autoantibodies have been discovered till now. Increased, >270 mg/dl serum IgG4 level seems to be quite specific but not enough sensitive in the diagnosis of type 1 AIP, and IgG4 has no value in type 2. Other organ involvement can be useful again in the diagnosis of type 1 AIP. In addition, imaging alterations do not distinguish between type 1 and type 2. Thus, type 2 AIP almost always requires biopsy and histology; in its absence the diagnosis can be only highly probable but not definitive [30]. Type 1 AIP can be definitely demonstrated without biopsy in the majority of cases. However, several patients have an undetermined AIP, which is named NOS [31], a mixture of seronegative type 1 and possible type 2 cases. A useful simple algorithm in the differential diagnosis is

After the diagnosis of AIP, the classification has practical and prognostic significance. As described above, characteristic image on MRI associated with serum IgG4 level more than double of upper limit of normal (>270 mg%) and/ or simultaneous or sometimes previous presence of IgG4-related disease in other organs are sufficient to establish definitive diagnosis of type 1 AIP, even without histology. If IgG4 is normal and the only associated disease is ulcerative colitis or Crohn's disease, the classification in type 2 AIP is probable, but not definitive. If the patient does not have any associated disease, only NOS AIP is the clinically

Focal Diffuse, irregular Atrophy

upstream dilatation

*Note the unique combination of findings in autoimmune pancreatitis. The absence of more significant upstream dilatation of pancreatic duct and altered signal in the parenchyma, both useful as compared to pancreatic cancer. On the other hand, the absence of necrosis and peripancreatic fluid collections helps to distinguish it as compared to acute* 

*Characteristic alterations in pancreatic and peripancreatic morphology, useful in the differential diagnosis.*

Focal or diffuse Stricture +/− slight

**Increase in size Dilatation of ducts Parenchyma Neighborhood**

+/− calcifications

Altered signal, contrast enhancement and diffusion

Marked upstream Upstream atrophy Metastasis in

collections

—

—

lymph nodes

Diffuse No Edema +/− necrosis Fluid

Head, groove Upstream, regular Normal —

• Conditions of very strict and early control are assured.

withdrawn and the patient goes to surgery.

proposed in **Figure 7**.

Acute pancreatitis

Chronic pancreatitis

Groove pancreatitis

Autoimmune pancreatitis

Pancreatic cancer

*pancreatitis.*

**Table 2.**

Focal (hypovascular mass)

**100**

*A simplified algorithm for the differential diagnosis and treatment of autoimmune pancreatitis. Briefly: Once AIP is suspected on the basis of medical history or abdominal US findings, CT scan or MRI is performed, of course completed with determination of the IgG4 level in the serum. These data can be sufficient to establish definitive diagnosis of AIP or pancreatic cancer and initiate proper treatment. The effect of steroid treatment must be confirmed after a short time, about 2 weeks: if no improvement is detectable, the diagnosis of AIP is improbable, and the patients must be reevaluated for surgery or at least biopsy. If the initial workup gives an equivocal result, EUS and biopsy (not cytology!) is necessary to define the diagnosis and treatment. CT, computed tomography; MRI, magnetic resonance imaging; EUS, endosonography; Cht, chemotherapy.*

#### **Figure 8.**

*Classification of AIP in different subclasses. Type 1 can be frequently demonstrated without histology, while definitive diagnosis of type 2 requires biopsy in the majority of cases. NOS is clinically a useful category, in particular, when no biopsy is available. For details, see text. LPSP, lymphoplasmacytic sclerosing pancreatitis; GEL, granulocytic epithelial lesion; NOS, Not Otherwise Specified; IBD, inflammatory bowel disease.*

possible diagnosis. In these latter cases, pancreatic biopsy is advisable, guided by EUS and taking core biopsy, not cytology. Several cases will show typical histology of type 1 AIP. In others, the absence of significant IgG4-positive lymphoplasmacytic infiltration and the presence of granulocytic epithelial lesions with or without neutrophil infiltration of the pancreatic lobules prove definitively type 2 AIP. However, typical histological features of type 2 can be also absent in the core biopsy: in these cases the diagnosis continues to be NOS or sometimes probable type 2 (**Figure 8**).
