Endoscopic ultrasound-guided fine needle aspiration in the differentiation of type 1 and type 2 autoimmune pancreatitis

Can serum immunoglobulin G4 levels and age serve as reliable predictors of relapse in autoimmune pancreatitis?

We are writing in response to the paper published in the World Journal of Gastroenterology by Zhou et al. The authors identified higher serum immunoglobulin (Ig) G4 levels and age over 55 years as independent risk factors for disease relapse. Despite notable strengths, it is crucial to address potential biases. Firstly, the cohort study included 189 patients with autoimmune pancreatitis (AIP) type 1 (with higher IgG4 seropositivity and higher relapse) and 24 with type 2 (with lower IgG4 seropositivity and lower relapse). Consequently, most, if not all, AIP type 2 patients were assigned to the normal group, possibly inflating the association of higher serum IgG4 levels with relapse and potentially exaggerating the association of older age with relapse. Secondly, the authors did not provide sufficient details regarding AIP diagnosis, such as the ratio of definitive vs probable cases and the proportion of biopsies. In cases where histological evidence is unavailable or indeterminate, AIP type 2 may be misdiagnosed as definitive type 1, and type 1 may also be misdiagnosed as probable type 2, particularly in cases with normal or mildly elevated serum IgG4 levels. Lastly, in this retrospective study, approximately one-third of the consecutive patients initially collected were excluded for various reasons. Accordingly, the impact of non-random exclusion on relapse outcomes should be carefully considered. In conclusion, the paper by Zhou et al offers plausible, though not entirely compelling, evidence suggesting a predictive role of elevated serum IgG4 levels and advanced age in AIP relapse. The foundation for future investigations lies in ensuring a reliable diagnosis and accurate disease subtyping, heavily dependent on obtaining histological specimens. In this regard, endoscopic ultrasound-guided fine-needle biopsy emerges as a pivotal component of the diagnostic process, contributing to mitigating biases in future explorations of the disease.

Autoimmune pancreatitis type 2 (idiopathic duct-centric pancreatitis): A comprehensive review

Autoimmune pancreatitis (AIP) is an uncommon fibro-inflammatory disorder precipitated by autoimmune/inflammatory reactions. Currently, there are two clinical subtypes of AIP (type 1 [AIP-1] and type 2 [AIP-2]) that correspond to two histologic descriptors (lymphoplasmacytic sclerosing pancreatitis and idiopathic duct-centric pancreatitis, respectively). While our understanding of AIP-1 has evolved considerably over the years, little is known about AIP-2 due to its rarity, often leading to misdiagnosis, delayed treatment, and even unnecessary surgical resection. Compared to AIP-1, AIP-2 exhibits distinct clinical and histologic features. Because AIP-2 is a pancreas-restricted disease without a specific serum marker, the evaluation of histologic features (e.g., granulocytic epithelial lesions) is essential for an accurate diagnosis. Patients with AIP-2 respond well to glucocorticoids, with anti-tumor necrosis factor-alpha antibodies as a promising alternative therapy. The prognosis of AIP-2 is generally favorable and relapse is uncommon. Here, we provide an overview of our current knowledge on the clinical features, diagnosis, therapeutic regimens, prognosis, and putative mechanisms underlying AIP-2. Notably, the diagnostic differentiation between AIP-2, especially the mass-forming/focal type, and pancreatic cancer is important, but challenging. In this regard, endoscopic ultrasound-guided core biopsy has a key role, but novel diagnostic markers and modalities are clearly needed.

Utility of Endoscopic Ultrasound-Guided Fine-Needle Aspiration and Biopsy for Histological Diagnosis of Type 2 Autoimmune Pancreatitis

In Japan, type 1 autoimmune pancreatitis (AIP) is the most common type of AIP; type 2 AIP is rare. The aim of this study was to clarify the usefulness of endoscopic ultrasound-guided fine-needle aspiration and biopsy (EUS-FNAB) for the diagnosis of type 2 AIP. We analyzed the tissue specimens of 10 patients with suspected type 2 AIP who underwent EUS-FNAB at our hospital between April 2009 and March 2021 for tissue volume and histopathological diagnostic performance. The male-to-female ratio of the patients was 8:2, and the patient age (mean ± standard deviation) was 35.6 ± 15.5 years. EUS-FNAB provided sufficient tissue volume, with high-power field >10 in eight patients (80.0%). Based on the International Consensus Diagnostic Criteria (ICDC), four patients (40.0%) had histological findings corresponding to ICDC level 1, and five patients (50.0%) had histological findings corresponding to ICDC level 2. The results of this study show that EUS-FNB can be considered an alternative method to resection and core-needle biopsy for the collection of tissue samples of type 2 AIP.

Biopsy diagnosis of type 1 autoimmune pancreatitis: Does it bring a conclusion or confusion?

A biopsy-based diagnosis of type 1 autoimmune pancreatitis (AIP) is now feasible via an endoscopic ultrasound-guided fine-needle biopsy, but there are potential issues to address. The benefits of acquiring large tissue samples include more successful immunostaining for Immunoglobulin G4 and more identifications of storiform fibrosis, obliterative phlebitis, and the ductal lesions of type 1 AIP. However, storiform fibrosis may not be present in all the type 1 AIP lesions. An interobserver agreement study revealed only slight-to-moderate agreement among pathologists diagnosing the histological findings of type 1 AIP. Potential reasons for disagreement are the different time phases of the inflammation (which result in heterogeneous histological pictures), a focal appearance of the typical histological findings, and the different definitions used by pathologists. We have thus devised guidance for diagnosing type 1 AIP based on biopsy tissues. In this guidance, we define each histological finding of type 1 AIP, for example, storiform fibrosis as a swirling arrangement of inflammatory cells, spindle-shaped cells, and delicate collagens as a unit. The necessity of elastic stains for identifying obliterative phlebitis is explained, with examples of mimickers. Another important purpose of a biopsy in type 1 AIP cases is differentiation from pancreatic ductal adenocarcinoma (PDAC). In this situation, acinar-ductal metaplasia observed in type 1 AIP is a mimicker of PDAC and should not be confused. For the resolution of potential disagreements among pathologists, a multi-disciplinary approach with the collaboration of clinicians, radiologists, and pathologists is necessary to avoid confusion.

Concordance of the histological diagnosis of type 1 autoimmune pancreatitis and its distinction from pancreatic ductal adenocarcinoma with endoscopic ultrasound-guided fine needle biopsy specimens: an interobserver agreement study

The histological diagnosis of type 1 autoimmune pancreatitis (AIP) based on the findings obtained by an endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) is feasible, but the diagnostic consistency of this method has not been confirmed. We determined the interobserver agreement among 20 pathologists regarding the diagnosis of type 1 AIP, including the distinction from pancreatic ductal adenocarcinoma (PDAC) using large tissue samples obtained by EUS-FNB. After guidance for diagnosing AIP with biopsy tissues was provided, a round 2 was performed. The median sensitivity and specificity for diagnosing PDAC vs. non-neoplastic diseases were 95.2% and 100%, respectively. In groups of specialists (n = 7) and the generalists (n = 13), Fleiss' к-values increased from 0.886 to 0.958 and from 0.750 to 0.816 in round 2. The concordance was fair or moderate for obliterative phlebitis and storiform fibrosis but slight for ductal lesion of type 1 AIP. Discordant results were due to ambiguous findings and biopsy tissue limitations. Among the specialists, the ratio of cases with perfect agreement regarding the presence of storiform fibrosis increased in round 2, but agreement regarding obliterative phlebitis or ductal lesions was not improved. Although the histological definite diagnosis of type 1 AIP was achieved by most observers in > 60% of the cases, the confidence levels varied. Because some ambiguities exist, the histological diagnostic levels based on the diagnostic criteria of type 1 AIP should not be taken for granted. Guidance is effective for improving accurate PDAC diagnoses (notably by recognizing acinar-ductal metaplasia) and for evaluating storiform fibrosis.

Endoscopic ultrasound-guided pancreatic sampling for the histopathological diagnosis of autoimmune pancreatitis

Autoimmune pancreatitis (AIP), which is characterized by pancreatic enlargement and irregular narrowing of the main pancreatic duct, is difficult to differentiate from malignancy. The irregular narrowing of the pancreatic duct, which can be detected via endoscopic retrograde cholangiopancreatography, is a characteristic feature of AIP; however, distinguishing between localized AIP and pancreatic cancer based on pancreatic duct imaging is difficult. This study overviews the efficacy of endoscopic ultrasound (EUS)-guided pancreatic sampling for the histopathological diagnosis of AIP. Recent enhancements in needle biopsy methodologies and technologies have contributed to improvement in the diagnostic efficacy of this technique. The guidance provided in this study for the histological diagnosis of AIP is anticipated to further advance in the histopathological diagnosis of AIP using EUS-guided pancreatic sampling.

Current status of type 1 (IgG4-related) autoimmune pancreatitis

In 1995, Yoshida et al. proposed first the concept of "autoimmune pancreatitis" (AIP). Since then, AIP has been accepted as a new pancreatic inflammatory disease and is now divided two subtypes. Type 1 AIP affected immunoglobulin G4 (IgG4) and implicates the pancreatic manifestation of IgG4-related disease, while type 2 is characterized by neutrophil infiltration and granulocytic epithelial lesions (GEL). Recent research has clarified the clinical and pathophysiological aspects of type 1 AIP, which is more than type 2 among the Japanese population. However, many details remain unclear about the pathogenesis and progression of this disease. In this review, we discuss the current knowledge and recent advances relating to type 1 AIP.

Endoscopic ultrasound-guided fine needle aspiration versus biopsy for diagnosis of autoimmune pancreatitis: Systematic review and comparative meta-analysis

BACKGROUND

Endoscopic ultrasound (EUS) is recommended for guiding the acquisition of pancreatic tissue in patients with suspected autoimmune pancreatitis (AIP). Data comparing EUS-guided fine needle aspiration (FNA) and fine needle biopsy (FNB) sampling in the diagnosis of AIP are limited.

METHODS

A comprehensive literature search of the PubMed, EMBASE, and Ovid MEDLINE databases was conducted until April 2020. The pooled rates of diagnostic yield for the histologic criteria of AIP, histologic tissue procurement, and adverse events were compared between FNA and FNB. Diagnostic yields were also compared between 19 gauge (G) and 22G needles.

RESULTS

This meta-analysis included nine studies comprising 309 patients with AIP who underwent FNA and seven studies comprising 131 patients who underwent FNB. The pooled diagnostic yields for level 1 or 2 histology criteria of AIP were 55.8% (95% confidence interval (CI) 37.0-73.9%, I²  = 91.1) for FNA and 87.2% (95% CI 68.8-98.1%, I²  = 69.4) for FNB (P = 0.030). The pooled histologic procurement rates for FNA and FNB were 91.3% (95% CI, 84.9-97.6%, I²  = 82.9) and 87.0% (95% CI, 77.8-96.1%, I²  = 40.0), respectively (P = 0.501). Adverse events were comparable between two groups. When analyzed by needle size, the diagnostic yield was better with a 19G needle than with a 22G needle (88.9% vs. 60.6%, P = 0.023).

CONCLUSIONS

The diagnostic yield may be better with FNB needles than with FNA needles for the diagnosis of AIP, despite the similar rate of histologic tissue procurement. A quantitative definition for the histologic sample adequacy for AIP may be warranted.

Histological features of autoimmune pancreatitis and IgG4-related sclerosing cholangitis with a correlation with imaging findings

Autoimmune pancreatitis (AIP) is characterized by a tumefactive inflammatory lesion resembling pancreatic carcinoma. Type 1 AIP is a pancreatic manifestation of IgG4-related disease characterized by unique histological features that can be identified on imaging. The capsule-like rim, which is a collar of hypertrophic lesion surrounding the pancreas, consists of lymphoplasmacytic infiltration and fibrosis, and storiform fibrosis is often identified. Hypertrophic lesions of various microscopic architectures such as the ducts, veins (obliterative phlebitis), arteries (periarteritis), and nerves are observed without parenchymal damage. The pancreatic lobules keep their contours, but the acinar cells are diminished and replaced by numerous inflammatory cells. These features provide clues to arrive at a diagnosis of type 1 AIP and to distinguish it from pancreatic carcinoma on imaging. In contrast, type 2 AIP is an epithelium-centered inflammation involving the ducts and lobules. Neutrophilic infiltration in the epithelium and/or lumens (granulocytic epithelial lesion) is a characteristic finding. Lobular swelling due to inflammation is the cause of pancreatic enlargement. IgG4-related sclerosing cholangitis is histologically similar to the hypertrophic ductal lesion in type 1 AIP and characterized by wall thickening due to inflammation and luminal stenosis. The epithelium is intact, which is different from bile duct carcinomas and primary sclerosing cholangitis, the latter of which is characterized by inflammation targeting the epithelium. Although the histological features of type 1 AIP and IgG4-related sclerosing cholangitis are unique, the biopsy diagnosis of these diseases has limitations, which should be recognized by clinicians.

Endoscopic ultrasound-guided tissue acquisition for the histopathological diagnosis of autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a disease concept that originated in Japan. It is characterized by diffuse pancreatic enlargement and irregular narrowing of the main pancreatic duct. Although the usefulness of the histological diagnosis of AIP using endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) and EUS-guided fine-needle biopsy (FNB) has been reported, enhanced diagnostic performance is expected with improvements in tissue collection methods and fine-needle techniques. Guidance for establishing the tissue diagnosis of AIP has been developed and is useful for histological evaluation. Histopathological diagnosis by EUS-FNA/FNB is expected to play a central role in AIP diagnosis in the future.

The Role of EUS-Guided FNA and FNB in Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is an increasingly recognized disease classified into two different subtypes based on histology. According to the International Diagnostic Criteria (ICDC), the diagnosis is achieved using a combination of different criteria. In patients presenting with a typical imaging appearance, the diagnosis may be straightforward, and steroid treatment is recommended, even without histological confirmation. In patients with atypical imaging or mass-forming appearance, the differential diagnosis with pancreatic cancer is challenging and crucial for treatment strategy. Endoscopic ultrasound (EUS)-guided tissue acquisition has been proposed to achieve a histological diagnosis. Fine-needle aspiration (FNA) was first proposed to aspirate cells from pancreatic lesions. Despite excellent results in terms of sensitivity for pancreatic cancer, the data are disappointing regarding the diagnosis of AIP. The recent development of new needles allowing fine-needle biopsy (FNB) has been associated with improved diagnostic accuracy based on preserving the tissue architecture, which is necessary to detect the typical histological features of AIP. However, the published literature on the role of EUS-guided FNA and FNB is limited and mainly focused on type 1 AIP. The present study aimed to review the available literature on the role of EUS-guided FNA and FNB in the diagnosis of AIP.

The role of apparent diffusion coefficient value in the diagnosis of localized type 1 autoimmune pancreatitis: differentiation from pancreatic ductal adenocarcinoma and evaluation of response to steroids

PURPOSE

The aim of this study was to clarify the usefulness of the apparent diffusion coefficient (ADC) value in the differential diagnosis of localized autoimmune pancreatitis (AIP) and pancreatic ductal adenocarcinoma (PDAC) and the evaluation of response to steroids.

METHODS

This study retrospectively analyzed 40 patients with localized AIP and 71 patients with PDAC who underwent abdominal MRI with DWI (b = 0 and 1000 s/mm²). Their ADC values at the lesion sites and five MRI findings useful for diagnosing AIP were evaluated. In addition, ADC values before and after steroid therapy were compared in 28 patients with localized AIP.

RESULTS

The median ADC value was significantly lower for localized AIP than for PDAC (1.057 × 10^-3 vs 1.376 × 10^-3 mm²/s, P < 0.001). In the ROC curve analysis, the area under the curve was 0.957 and optimal cut-off value of ADC for differentiating localized AIP from PDAC was 1.188 × 10^-3 mm²/s. ADC value ≤ 1.188 × 10^-3 mm²/s showed the highest sensitivity and accuracy among the MRI findings (92.6% and 90.7%, respectively), and when combined with one or more other MRI findings, showed 96.3% specificity. The median ADC values before and after steroid therapy (mean 7.9 days) were 1.061 × 10^-3 and 1.340 × 10^-3 mm²/s, respectively, and ADC values were significantly elevated after steroid induction (P < 0.001).

CONCLUSION

The measurement of ADC values was useful for the differential diagnosis of localized AIP and PDAC and for the early determination of the effect of steroid therapy.

Late-onset type-2 autoimmune pancreatitis with two mass lesions diagnosed by endoscopic ultrasound-guided fine-needle aspiration

A 65-year-old man with ulcerative colitis presented with aggravated diabetes. Computed tomography showed two masses in the body and tail of the pancreas. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) was performed, with histopathological findings suggesting autoimmune pancreatitis (AIP). Type-2 AIP was suspected, and administration of prednisolone was initiated. The pancreatic masses had disappeared after the treatment. In this case, EUS-FNA was effective for the diagnosis of type-2 AIP. The two-lesion mass formation observed here is a rare presentation of the disease. In patients with a history of ulcerative colitis, the possibility of late-onset type-2 AIP should be kept in mind.

Utility of a 21-gauge Menghini-type biopsy needle with the rolling method for an endoscopic ultrasound-guided histological diagnosis of autoimmune pancreatitis: a retrospective study

Background

The histological diagnosis of autoimmune pancreatitis (AIP) by an endoscopic ultrasound (EUS)-guided approach is still challenging.

Methods

We investigated the utility of the 21-gauge Menghini-type biopsy needle with the rolling method for the histological diagnosis of AIP, in comparison with conventional 22-gauge needles. Among total 28 patients, rate of definitive histological diagnosis, acquired sample area of tissue, rate of histopathological diagnosis of AIP, and adverse events were retrospectively analyzed.

Results

Definitive histological diagnoses were successfully accomplished in all 14 patients (100%) treated with a Menghini-type needle, and in 57% of cases (8/14) treated with conventional 22-gauge needles (P < 0.001). The median sample area of the tissue, except for blood contamination, was remarkably larger by the Menghini-type needle than by conventional-type needles (6.2 [IQR, 4.5–8.8] versus 0.7 [IQR, 0.2–2.0] mm², P < 0.001), and the area per punctures was approximately 4 times larger (1.4 [IQR: 0.9–2.9] versus 0.3 [IQR: 0.1–0.6] mm²/puncture, P < 0.001). Based on the International Consensus Diagnostic Criteria, lymphoplasmacytic infiltration, abundant IgG4-postive cells, storiform fibrosis, and obliterative phlebitis were found in 86%/29%, 64%/0%, 36%/0%, and 7%/0% patients who were treated with the Menghini-type needle and conventional-type needles, respectively. Consequently, histopathological diagnosis with type 1 AIP (lever 1 or 2) was achieved in 9 patients (64%) treated with the Menghini-type needle and in no patient treated with conventional-type needles (P < 0.001). Two patients who had mild post-procedural pancreatitis improved with conservative treatment, and no bleeding occurred in patients treated with the Menghini-type needle.

Conclusion

EUS-guided rolling method with the 21-gauge Menghini-type biopsy needle is useful for the histopathological diagnosis of AIP, due to its abundant acquisition of good-quality tissue from the pancreas.

Diagnostic yield of endoscopic ultrasound-guided tissue acquisition in autoimmune pancreatitis: a systematic review and meta-analysis

Background and study aims  There is limited evidence on the diagnostic performance of endoscopic ultrasound (EUS)-guided tissue acquisition in autoimmune pancreatitis (AIP). The aim of this meta-analysis was to provide a pooled estimate of the diagnostic performance of EUS-guided fine-needle aspiration (FNA) and fine-needle biopsy (FNB) in patients with AIP. Patients and methods  Computerized bibliographic search was performed through January 2020. Pooled effects were calculated using a random-effects model by means of DerSimonian and Laird test. Primary endpoint was diagnostic accuracy compared to clinical diagnostic criteria. Additional outcomes were definitive histopathology, pooled rates of adequate material for histological diagnosis, sample adequacy, mean number of needle passes. Diagnostic sensitivity and safety data were also analyzed. Results  Fifteen studies with 631 patients were included, of which four were prospective series and one randomized trial. Overall diagnostic accuracy of EUS tissue acquisition was 54.7 % (95 % confidence interval, 40.9 %-68.4 %), with a clear superiority of FNB over FNA (63 %, 52.7 % to 73.4 % versus 45.7 %, 26.5 %-65 %; p < 0.001). FNB provided level 1 of histological diagnosis in 44.2 % of cases (30.8 %-57.5 %) as compared to 21.9 % (10 %-33.7 %) with FNA ( P  < 0.001). The rate of definitive histopathology of EUS tissue sampling was 20.7 % (12.9 %-28.5 %) and it was significantly higher with FNB (24.3 %, 11.8 %-36.8 %) as compared to FNA (14.7 %, 5.4 %-23.9 %; P  < 0.001). Less than 1 % of subjects experienced post-procedural acute pancreatitis. Conclusion  The results of this meta-analysis demonstrate that the diagnostic performance of EUS-guided tissue acquisition is modest in patients with AIP, with an improved performance of FNB compared to FNA.

The Diagnosis of Autoimmune Pancreatitis Using Endoscopic Ultrasonography

Autoimmune pancreatitis (AIP) is characterized by enlargement of the pancreas and irregular narrowing of the main pancreatic duct. It is often associated with IgG4-related sclerosing cholangitis (IgG4-SC), in which the bile duct narrows. Although characteristic irregular narrowing of the pancreatic duct caused by endoscopic retrograde cholangiopancreatography is noted in AIP, it is difficult to differentiate between localized AIP and pancreatic carcinoma based on imaging of the pancreatic duct. While stenosis of the bile duct in IgG4-SC is characterized by longer-length stenosis than in cholangiocarcinoma, differentiation based on bile duct imaging alone is challenging. Endoscopic ultrasound (EUS) can characterize hypoechoic enlargement of the pancreas or bile duct wall thickening in AIP and IgG4-SC, and diagnosis using elastography and contrast-enhanced EUS are being evaluated. The utility of EUS-guided fine needle aspiration for the histological diagnosis of AIP has been reported and is expected to improve diagnostic performance for AIP. Findings in the bile duct wall from endoscopic retrograde cholangiopancreatography followed by intraductal ultrasonography are useful in differentiating IgG4-SC from cholangiocarcinoma. Diagnoses based on endoscopic ultrasonography play a central role in the diagnosis of AIP.

Role of Endoscopic Ultrasonography-Guided Fine Needle Aspiration/Biopsy in the Diagnosis of Autoimmune Pancreatitis

Type 1 autoimmune pancreatitis (AIP) is histologically characterized by lymphoplasmacytic sclerosing pancreatitis (LPSP). Recently, the diagnostic yield of endoscopic ultrasonography-guided fine needle aspiration/biopsy (EUS-FNA/B) for AIP has been reported. However, its role in the diagnostic flow of AIP is not fully elucidated. We retrospectively reviewed 53 consecutive patients who were suspected with AIP and underwent EUS-FNA/B. We evaluated the contribution of EUS-FNA/B to the diagnosis of AIP before considering response to steroid therapy among patients with diffuse enlargement of the pancreas and those with focal enlargement, respectively. Twenty-two patients showed diffuse pancreatic enlargement and 31 showed focal enlargement. The final diagnosis was definitive AIP in 32 patients, probable AIP in 2, possible AIP in 1, and mass-forming focal pancreatitis in 18. There was no change in diagnosis after EUS-FNA/B among patients with diffuse pancreatic enlargement, while diagnosis changed in 38.7% (12/31) among those with focal enlargement—there was a probable to definitive diagnosis in 4 patients, unspecified to definitive in 3, and unspecified to probable in 5. EUS-FNB provided a significantly higher sensitivity for typical pathological findings of LPSP than EUS-FNA, and 10 patients were diagnosed as pathologically definitive AIP by EUS-FNB, though none were by EUS-FNA (p = 0.002). EUS-FNA/B was useful in the diagnosis of focal type AIP, and steroid therapy could be introduced after the diagnosis was confirmed. Meanwhile, EUS-FNA/B provided no contribution to diagnosis of diffuse type AIP. EUS-FNB showed a higher diagnostic yield than FNA.

Autoimmune pancreatitis type 2

PURPOSE OF REVIEW

Type 2 autoimmune pancreatitis (AIP) is a rare inflammatory disease of the pancreas. Very few data have been published on this particular subtype, which differs from the 'classical' IgG4-related type 1 AIP in terms of pathological features, epidemiology and risk of relapse. The aim of the current review is to summarize the available literature, suggesting a diagnostic and therapeutic approach to this disease.

RECENT FINDINGS

Based on the International Consensus Diagnostic Criteria, to achieve a 'definitive' diagnosis of type 2 AIP, histology is required. If a definitive histological diagnosis is lacking (not-performed or inconclusive), concomitant presence of inflammatory bowel disease (IBD) and effective response to steroids are needed for a 'probable' diagnosis of type 2 AIP.

SUMMARY

Type 2 AIP is a selective pancreatic disease, without association to other organ involvement. The lack of validated serological markers makes the diagnosis challenging in clinical practice, particularly in focal forms. A careful evaluation of the clinical profile (especially of a concomitant IBD), associated with an accurate imaging, might help in clinical practice to suspect type 2 AIP. Response to steroids is crucial to achieve diagnosis in patients without a diagnostic histology.

Efficacy and limitations of the histological diagnosis of type 1 autoimmune pancreatitis with endoscopic ultrasound-guided fine needle biopsy with large tissue amounts

OBJECTIVES

We examined the efficacy and limitations of acquiring large specimens by endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) for diagnosing type 1 autoimmune pancreatitis (AIP).

METHODS

Patients from 12 institutions with non-neoplastic diseases or pancreatic ductal adenocarcinoma (PDAC) with large EUS-FNB specimens were investigated. Slides stained with hematoxylin-eosin, elastic, IgG4, and IgG stains were evaluated. The IgG4- and IgG-positive cell numbers were counted in three foci. The diagnoses were based on the Japan Pancreas Society 2011 (JPS 2011) criteria and the International Consensus Diagnostic Criteria (ICDC).

RESULTS

We analyzed 85 non-neoplastic (definite type 1 AIP in 73/85 based on the ICDC) cases and 64 PDAC cases. IgG4-positive cells were numerous (>10 in 85.9%), and the IgG4/IgG ratios were high (>40% in 81.2%). Plasma cell crushing by an artifact caused unsuccessful immunostaining, notably in smaller samples. Tissue lengths were an important factor for the presence of storiform fibrosis and obliterative phlebitis, but storiform fibrosis was equivocal even in large tissues. A definite or possible histological diagnosis was achieved in 45.9% (39/85) and 41.2% (35/85), respectively, and contributed to the definite final diagnosis of type 1 AIP in 33.3% (ICDC) and 55.6% (JPS 2011) in cases with segmental/focal lesions. In the PDAC group, >10 IgG4-positive cells was rare (2/58), but elastic stains revealed fibrous venous occlusions in 10.3% (6/58).

CONCLUSIONS

EUS-FNB with large tissue amounts was useful for diagnosing type 1 AIP, notably by facilitating successful IgG4 immunostaining, but definite diagnosis may not be achieved even in cases with large specimens.

European Guideline on IgG4-related digestive disease - UEG and SGF evidence-based recommendations

The overall objective of these guidelines is to provide evidence-based recommendations for the diagnosis and management of immunoglobulin G4 (IgG4)-related digestive disease in adults and children. IgG4-related digestive disease can be diagnosed only with a comprehensive work-up that includes histology, organ morphology at imaging, serology, search for other organ involvement, and response to glucocorticoid treatment. Indications for treatment are symptomatic patients with obstructive jaundice, abdominal pain, posterior pancreatic pain, and involvement of extra-pancreatic digestive organs, including IgG4-related cholangitis. Treatment with glucocorticoids should be weight-based and initiated at a dose of 0.6-0.8 mg/kg body weight/day orally (typical starting dose 30-40 mg/day prednisone equivalent) for 1 month to induce remission and then be tapered within two additional months. Response to initial treatment should be assessed at week 2-4 with clinical, biochemical and morphological markers. Maintenance treatment with glucocorticoids should be considered in multi-organ disease or history of relapse. If there is no change in disease activity and burden within 3 months, the diagnosis should be reconsidered. If the disease relapsed during the 3 months of treatment, immunosuppressive drugs should be added.

Can the wet suction technique change the efficacy of endoscopic ultrasound-guided fine-needle aspiration for diagnosing autoimmune pancreatitis type 1? A prospective single-arm study

BACKGROUND

Other than surgery, endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is the only procedure for histologically diagnosing autoimmune pancreatitis (AIP). However, adequate specimens are difficult to obtain. Recently, more adequate specimens were reported to be obtained with EUS-FNA with a wet suction technique (WEST) than with conventional EUS-FNA.

AIM

To histologically diagnose AIP by EUS-FNA with a WEST.

METHODS

Eleven patients with possible type 1 AIP between February 2016 and August 2018 underwent EUS-FNA with a WEST (WEST group), with four punctures by 19 or 22 G needles. As a historical control, 23 type 1 AIP patients who underwent no fewer than four punctures with 19 or 22 G needles were enrolled (DRY group). Patient characteristics and histological findings were compared between the two groups.

RESULTS

Three histopathological factors according to the International Consensus Diagnostic Criteria were significantly greater in the WEST group than the DRY group [lymphoplasmacytic infiltrate without granulocytic infiltration: 9 (81.8%) vs 6 (26.1%), P = 0.003, storiform fibrosis: 5 (45.5%) vs 1 (4.3%), P = 0.008, abundant (> 10 cells/HPF) IgG4-positive cells: 7 (63.6%) vs 5 (21.7%), P = 0.026]. Level 1 or level 2 histopathological findings were observed more often in the WEST group than in the DRY group [8 (72.7%) vs 3 (13.0%), P = 0.001].

CONCLUSION

EUS-FNA with a WEST was more successful than standard EUS-FNA in histologically diagnosing AIP.

Present state of endoscopic ultrasonography-guided fine needle aspiration for the diagnosis of autoimmune pancreatitis type 1

Autoimmune pancreatitis (AIP) is defined as pancreatitis caused by irregular narrowing of the pancreatic duct accompanied by pancreatic swelling, fibrosis and lymphocyte infiltration, events that are related to autoimmune mechanisms. The 2010 International Consensus Diagnostic Criteria for AIP defined pancreatitis as “type 1” when increased levels of serum IgG4 were present and other organs were involved; lymphoplasmacytic sclerosing pancreatitis was the main histological characteristic. Apart from surgery, endoscopic ultrasonography-guided fine needle aspiration (EUS-FNA) is the only method for the histological diagnosis of AIP; however, this method is difficult. The use of larger-diameter FNA needles and trucut biopsy did not improve the diagnostic performance of EUS-FNA, but it has improved gradually. In this review, we look back at past efforts to improve the diagnostic performance of EUS-FNA and reveal the present state of EUS-FNA for the histological diagnosis of AIP type 1.

Clinical and pathophysiological aspects of type 1 autoimmune pancreatitis

In 1995, Yoshida and colleagues proposed the concept of "autoimmune pancreatitis" (AIP), which has recently been recognized as a new pancreatic inflammatory disease. Recent studies have suggested the existence of two subtypes of AIP: type 1, which involves immunoglobulin G4 (IgG4) and is the pancreatic manifestation of IgG4-related disease (IgG4-RD); and type 2, which is characterized by granulocytic epithelial lesions. Type 2 AIP is thought to be rare in Japan. Type 1 AIP is characterized by increased serum IgG4 concentrations, lymphoplasmacytic infiltrations, storiform fibrosis, and obliterative phlebitis. However, although type 1 AIP has become increasingly recognized, many clinical and basic issues remain to be solved. This review provides an overview of the recent clinical and basic knowledge of type 1 AIP.

Present status and perspectives of endosonography 2017 in gastroenterology

Endoscopic ultrasound has become an essential tool in modern gastroenterology and abdominal surgery. Compared with all other endoscopic methods, it has the most potential for innovation and its future looks bright. Thus, we compiled this summary of established and novel applications of endoscopic ultrasound methods to inform the reader about what is already possible and where future developments will lead in improving patient care further. This review is structured in four parts. The first section reports on developments in diagnostic endoscopic ultrasound, the second looks at semi-invasive endoscopic ultrasound, and the third discusses advances in therapeutic endoscopic ultrasound. An overview on the future prospects of endoscopic ultrasound methods concludes this article.

Endoscopic Ultrasonography-Guided Fine Needle Aspiration Can Be Used to Rule Out Malignancy in Autoimmune Pancreatitis Patients

OBJECTIVES

The aim of this study was to review the suitability of endoscopic ultrasonography-guided fine needle aspiration (EUS-FNA) for ruling out malignancy in autoimmune pancreatitis patients.

METHODS

We retrospectively reviewed 40 autoimmune pancreatitis patients (type 1:37 patients; type 2: two patients; possible autoimmune pancreatitis: one patient) who received EUS-FNA. Among the 40 autoimmune pancreatitis patients, 34 were not histopathologically diagnosed with autoimmune pancreatitis by EUS-FNA, and they were followed up for more than 6 months in our hospital. Moreover, 14 pancreatic cancer patients who were not diagnosed by EUS-FNA were selected as a control group. These 14 patients constituted 3.9% of the 360 pancreatic cancer patients who received EUS-FNA. We evaluated the prognoses of the 34 autoimmune pancreatitis patients and the clinical differences between these 34 autoimmune pancreatitis patients and the 14 pancreatic cancer patients.

RESULTS

All 34 autoimmune pancreatitis patients showed reduced pancreatic swelling. The main pancreatic duct dilation ( > 3 mm), the diameter of the main pancreatic duct, the capsule-like rim sign, and serum CA19-9 levels were significantly different between the autoimmune pancreatitis and pancreatic cancer patients (2.9% versus 69.2%, P < .01; 1.7 ± 1.6 mm versus 6.8 ± 5.0 mm, P < .01; 79.4% versus 0%, P < .01; 41.4 ± 79.0 U/mL versus 2079.1 ± 275.3 U/mL, P = .02).

CONCLUSIONS

Almost all pancreatic cancers can be diagnosed by EUS-FNA. Furthermore, other clinical characteristics of pancreatic cancer undiagnosed by EUS-FNA were different from autoimmune pancreatitis undiagnosed by EUS-FNA. Endoscopic ultrasonography-guided FNA can be used to rule out malignancy in autoimmune pancreatitis patients.

The Role of Endoscopic Ultrasound in the Diagnosis of Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is increasingly being recognized due to improved understanding of the disease and its criteria for diagnosis. The classic type 1 AIP can be diagnosed on clinical data, but type 2 AIP requires histologic confirmation. Current criteria incorporate cross-sectional imaging and endoscopic retrograde cholangiopancreatography in the diagnosis of AIP. However, endoscopic ultrasound (EUS) will likely have an increasing role in the diagnosis through its characteristic imaging, image-enhancing techniques, and its ability to acquire tissue through either fine needle aspiration or biopsy. This article will review the diagnostic challenges of AIP and the current role of EUS.

From Pathogenesis, Clinical Manifestation, and Diagnosis to Treatment: An Overview on Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is a special type of chronic pancreatitis which is autoimmune mediated. The international consensus diagnostic criteria (ICDC) 2011 proposed two types of AIP: type I is associated with histological pattern of lymphoplasmacytic sclerosing pancreatitis (LPSP), characterized by serum IgG4 elevation, whereas type 2 is named idiopathic duct-centric pancreatitis (IDCP), with granulocytic epithelial lesion (GEL) and immunoglobulin G4 (IgG4) negative. The pathogenic mechanism is unclear now; based on genetic factors, disease specific or related antigens, innate and adaptive immunity may be involved. The most common clinical manifestations of AIP are obstructive jaundice and upper abdominal pain. The diagnosis can be made by a combination of parenchymal and ductal imaging, serum IgG4 concentrations, pancreatic histology, extrapancreatic disease, and glucocorticoid responsiveness according to ICDC 2011. Because of the clinical and imaging similarities with pancreatic cancer, general work-up should be done carefully to exclude pancreatic malignant tumor before empirical trial of glucocorticoid treatment. Glucocorticoid is the most common drug for AIP to induce remission, while there still exists controversy on steroid maintenance and treatment for relapse. Further studies should be done to identify more specific serum biomarkers for AIP, the pathogenic mechanisms, and the treatment for relapse.

Pancreatic Cytopathology

Pancreatic cytopathology, particularly through the use of endoscopic ultrasound-guided fine-needle aspiration (FNA), has excellent specificity and sensitivity for the diagnosis of pancreatic lesions. Such diagnoses can help guide preoperative management of patients, provide prognostic information, and confirm diagnoses in patients who are not surgical candidates. Furthermore, FNA can be used to obtain cyst fluid for ancillary tests that can improve the diagnosis of cystic lesions. In this article, we describe the cytomorphological features and differential diagnoses of the most commonly encountered pancreatic lesions on FNA.

Prospective multicenter study on the usefulness of EUS-guided FNA biopsy for the diagnosis of autoimmune pancreatitis

BACKGROUND AND AIMS

In the International Consensus Diagnostic Criteria (ICDC), autoimmune pancreatitis (AIP) is classified into types 1 and 2, and its definite histopathology diagnosis can be made based only on surgical or core biopsy specimens. Although EUS-guided FNA (EUS-FNA) biopsy is a safe technique for the collection of pancreatic tissue, no consensus viewpoint has been reached with regard to the role of EUS-FNA biopsy in the diagnosis of AIP. This study investigated the utility of pancreatic tissue collected by EUS-FNA biopsy by using a standard 22-gauge aspiration needle in the diagnosis of AIP.

METHODS

Patients with suspected AIP were prospectively enrolled in Nagoya University Hospital and Nagoya University-affiliated institutions. Pancreatic tissue was collected from each by EUS-FNA biopsy with a standard 22-gauge aspiration needle.

RESULTS

Fifty patients were registered, including 45 with a final diagnosis of AIP. Lymphoplasmacytic infiltration and abundant immunoglobulin G4-positive plasmacyte infiltration (>10/high-power field) were detected in 36 (72%) and 27 (54%) patients, respectively. Obliterative phlebitis and storiform fibrosis were not detected in our study. Granulocytic epithelial lesions (GEL) were observed in 3 patients. The sensitivity, specificity, positive predictive value, and negative predictive value of EUS-FNA biopsy to definitively diagnose AIP were 7.9% (3/38), 100% (12/12), 100% (3/3), and 25.5% (12/47), respectively. Pathology evaluation of pancreatic tissue collected by EUS-FNA biopsy improved the diagnostic accuracy in 8 (16%) of the 50 patients.

CONCLUSIONS

In this study, EUS-FNA biopsy by using a standard 22-gauge aspiration needle is not an effective diagnostic method for most patients with AIP. The combination of level 2 histology diagnosis of AIP with other findings specified in the ICDC slightly improved the diagnostic accuracy, although it still remains insufficiently accurate for routine clinical use.(

CLINICAL TRIAL REGISTRATION NUMBER

000006297.).

Diagnosis, treatment and long-term outcomes of autoimmune pancreatitis in Spain based on the International Consensus Diagnostic Criteria: A multi-centre study

OBJECTIVES

Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis that has been reported worldwide for the last two decades. The aim of this study is to analyse the clinical profile of patients from Spain with AIP, as well as treatments, relapses and long-term outcomes.

METHODS

Data from 59 patients with suspected AIP that had been diagnosed in 15 institutions are retrospectively analysed. Subjects are classified according to the International Consensus Diagnostic Criteria (ICDC). Patients with type 1 AIP (AIP1) and type 2 AIP (AIP2) are compared. Kaplan-Meier methodology is used to estimate the overall survival without relapses.

RESULTS

Fifty-two patients met ICDC, 45 patients were AIP1 (86.5%). Common manifestations included abdominal pain (65.4%) and obstructive jaundice (51.9%). Diffuse enlargement of pancreas was present in 51.0%; other organ involvement was present in 61.5%. Serum IgG4 increased in 76.7% of AIP1 patients vs. 20.0% in AIP2 (p = 0.028). Tissue specimens were obtained in 76.9%. Initial successful treatment with steroids or surgery was achieved in 79.8% and 17.3%, respectively. Maintenance treatment was given in 59.6%. Relapses were present in 40.4% of AIP1, with a median of 483 days. Successful long-term remission was achieved in 86.4%.

CONCLUSIONS

AIP1 is the most frequent form of AIP in Spain in our dataset. Regularly, ICDC allows AIP diagnosis without the need for surgery. Steroid and chirurgic treatments were effective and safe in most patients with AIP, although maintenance was required many times because of their tendency to relapse. Long-term serious consequences were uncommon.

Endoscopic ultrasonography guided-fine needle aspiration for the diagnosis of solid pancreaticobiliary lesions: Clinical aspects to improve the diagnosis

Endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA) has been applied to pancreaticobiliary lesions since the 1990s and is in widespread use throughout the world today. We used this method to confirm the pathological evidence of the pancreaticobiliary lesions and to perform suitable therapies. Complications of EUS-FNA are quite rare, but some of them are severe. Operators should master conventional EUS observation and experience a minimum of 20-30 cases of supervised EUS-FNA on non-pancreatic and pancreatic lesions before attempting solo EUS-FNA. Studies conducted on pancreaticobiliary EUS-FNA have focused on selection of suitable instruments (e.g., needle selection) and sampling techniques (e.g., fanning method, suction level, with or without a stylet, optimum number of passes). Today, the diagnostic ability of EUS-FNA is still improving; the detection of pancreatic cancer (PC) currently has a sensitivity of 90%-95% and specificity of 95%-100%. In addition to PC, a variety of rare pancreatic tumors can be discriminated by conducting immunohistochemistry on the FNA materials. A flexible, large caliber needle has been used to obtain a large piece of tissue, which can provide sufficient histological information to be helpful in classifying benign pancreatic lesions. EUS-FNA can supply high diagnostic yields even for biliary lesions or peri-pancreaticobiliary lymph nodes. This review focuses on the clinical aspects of EUS-FNA in the pancreaticobiliary field, with the aim of providing information that can enable more accurate and efficient diagnosis.

Role of Endoscopic Ultrasound in Pediatric Disease

The application of endoscopic ultrasound (EUS) in children is growing, with studies demonstrating a positive impact of EUS in the management of childhood diseases. EUS has shown to be useful in the evaluation and management of a spectrum of childhood diseases including pancreaticobiliary disease, congenital anomalies, submuocsal lesions, biliary stones disease, inflammatory bowel disease, and eosinophilic esophagitis. Its diagnostic capabilities with fine-needle aspiration and core-needle biopsy are shown to be technically successful, safe, and effective in several pediatric studies. Therapeutic EUS procedures include endoscopic cystgastrostomy, celiac plexus neurolysis, and biliary access. This article discusses the role of EUS for diagnostic and therapeutic purposes in pediatrics.

Laparoscopic and Percutaneous Core Needle Biopsy Plays a Central Role for the Diagnosis of Autoimmune Pancreatitis in a Single-Center Study From Denmark

OBJECTIVES

The aims of this study were to describe the diagnosis of autoimmune pancreatitis (AIP) in Denmark and to test the usefulness of the International Consensus Diagnostic Criteria (ICDC) on a geographically well-defined cohort.

METHODS

All patients diagnosed with AIP at Odense University Hospital from 2007 to 2013 were included (n = 30; mean follow-up, 26.2 months). Data from laparoscopic or percutaneous ultrasound-guided core needle biopsy (CNB), resection specimens, endoscopic ultrasound (EUS), EUS-guided CNB, computed tomography, serum immunoglobulin G4 (IgG4), and pancreatography were retrospectively analyzed according to ICDC.

RESULTS

Twenty patients were diagnosed with type 1, 8 with type 2, and 2 with not otherwise specified AIP. Twenty-eight patients (93%) could correctly be classified when ICDC were retrospectively applied. Serum IgG4 was elevated in 44% of type 1 and 0% of type 2. Other organ involvement was observed in 40% of type 1 and 13% of type 2, but inflammatory bowel disease only in type 2 (P = 0.001). One patient had IgG4-related chronic perisplenitis as a hitherto undescribed manifestation of IgG4-related disease. Nineteen (91%) of 21 biopsied patients had diagnostic CNB features of AIP. Computed tomography, EUS, and pancreatography showed features highly suggestive or supportive of AIP in 68%, 72%, and 71%, respectively.

CONCLUSIONS

Laparoscopic or percutaneous ultrasound-guided CNB had the highest sensitivity for AIP. The ICDC could retrospectively correctly diagnose 93% of the patients.

Autoimmune pancreatitis complicated with inflammatory bowel disease and comparative study of type 1 and type 2 autoimmune pancreatitis

BACKGROUND

Two types of autoimmune pancreatitis (AIP) have been reported, lymphoplasmacytic sclerosing pancreatitis and idiopathic duct-centric chronic pancreatitis (IDCP), which are now recognized as type 1 and type 2 AIP, respectively. Since the clinical features of type 2 AIP have not been fully elucidated and this condition is frequently accompanied by inflammatory bowel disease (IBD), we performed a nationwide survey of patients with AIP complicated with IBD to precisely characterize this disease entity.

METHODS

We collected 138 cases of pancreatitis with complicating IBD from affiliated institutes specializing in AIP or IBD, and comparative study between the IDCP groups and type 1 AIP was performed.

RESULTS

Histological examination revealed 15 AIP cases to be IDCP of institutional diagnosis, among which 11 cases were upgraded to IDCP of central diagnosis by an expert pathologist. The IDCP group exhibited younger onset age, no gender bias, frequent abdominal pain, and normal IgG4 value, similar to those of type 2 AIP reported previously. We also witnessed a lower prevalence of jaundice in type 2 AIP than in type 1 AIP that corresponded to imaging findings of less frequent pancreatic head swelling and scarce bile duct stenosis.

CONCLUSIONS

A characteristic feature of type 2 AIP compared with type 1 AIP is a low frequency of obstructive jaundice that is related to rare lower bile duct stricture due to lower prevalence of pancreatic head swelling. Contrary to type 1 AIP, lower bile duct stricture in this condition has no apparent relation to sclerosing cholangitis.

Endoscopic ultrasound-guided fine-needle aspiration biopsy of autoimmune pancreatitis: diagnostic clues and pitfalls

INTRODUCTION

Autoimmune pancreatitis (AIP) is an inflammatory process that has characteristic clinical, radiographic, and pathologic features but may mimic pancreatic malignancy. In this study, we reviewed our experience in the endoscopic ultrasound-guided fine-needle aspiration evaluation of pancreatic lesions in patients with AIP.

MATERIALS AND METHODS

We searched the cytopathology archives and identified a total of 6 cases that had endoscopic ultrasound-guided fine-needle aspiration evaluation and subsequent tissue biopsy or resection with a diagnosis of AIP. The clinical, cytologic, and histopathologic features were reviewed.

RESULTS

The original cytologic diagnoses included negative, atypical, and suspicious for malignancy in 2 cases each. On retrospective review, these cases were characterized cytologically by the presence of mixed epithelial cells, mixed lymphocytes, and plasma cells, as well as cellular stromal fragments. Cytologic atypia of epithelial cells was observed in 4 of 6 cases, including mild (3 cases) and moderate (1 case) atypia. KRAS mutation analysis was performed in 4 cases with an indeterminate cytology diagnosis, which was negative in all cases.

CONCLUSIONS

Our results demonstrate that the presence of trilineage epithelial, lymphoplasmacytic, and stromal elements may be suggestive but not definitive for a diagnosis of AIP. The role of KRAS mutation analysis in AIP remains inconclusive and may warrant further evaluation.

Diagnosis and Treatment of Autoimmune Pancreatitis in China: A Systematic Review

AIMS

To provide comprehensive data on the diagnosis and treatment of autoimmune pancreatitis (AIP) patients in China.

DESIGN

A systematic review.

METHODS

All clinical studies concerning AIP from China published between January 2006 and June 2014 were retrospectively reviewed and analyzed.

RESULTS

A total of 26 original articles involving 706 AIP patients were included with an estimated proportion of type 2 AIP as 4.7%. In the 706 AIP patients, the range of mean/median age was 48.6-67.0 years old and the male to female ratio was 4.47:1. The common presentations included obstructive jaundice (pooled rate: 63.4%, 95%CI: 55.4%-71.0%) and abdominal symptoms (pooled rate: 62.3%, 95%CI: 52.4%-71.7%). Biliary involvement was the most common extrapancreatic manifestations, especially the lower part of the common bile duct (pooled rate: 62.3%, 95%CI: 49.9%-73.9%). According to the imaging examinations, 53.8% and 41.6% patients were classified into focal-type and diffuse-type, respectively. Notably, upstream pancreatic duct dilatation was found in parts of patients (pooled rate: 13.8%, 95%CI: 6.6%-23.1%). The levels of serum IgG4 were elevated in most patients (pooled rate: 86.0%, 95%CI: 74.2%-94.6%). Nearly three tenths AIP patients received surgery (pooled rate: 29.7%, 95%CI: 18.1%-42.8%) due to mimicked malignancy. Steroid treatment was given to 78.4% patients (95%CI: 65.3%-89.1%) with a pooled remission rate of 96.2% (95%CI: 94.0%-97.9%). The pooled relapse rate was 13.8% (95%CI: 7.2%-22.0%) with the mean follow-up time ranging from 12 to 45 months.

CONCLUSION

Type 1 is the predominant type of Chinese AIP patients and the clinical features, diagnostic modalities and therapeutic regimen were similar with those in other countries. Knowledge of AIP should be more widespread to avoid unnecessary surgery.

Nationwide epidemiological survey of autoimmune pancreatitis in Japan in 2011

OBJECTIVES

To clarify the clinicoepidemiological features of autoimmune pancreatitis (AIP) in Japan, a nationwide epidemiological survey was conducted.

METHODS

Patients with AIP who had visited selected hospitals in 2011 were surveyed. Autoimmune pancreatitis was diagnosed according to the revised clinical diagnostic criteria for AIP (Japan Pancreas Society 2011). The study consisted of 2 stage surveys; the number of patients with AIP was estimated by the first questionnaire, and their clinical features were assessed by the second questionnaire.

RESULTS

The estimated total number of AIP patients in 2011 was 5745 (95% confidence interval, 5325-6164), with an overall prevalence rate of 4.6 per 100,000 population. The number of patients who were newly diagnosed as AIP was estimated to be 1808 (95% confidence interval, 1597-2018), with an annual incidence rate of 1.4 per 100,000 population. The sex ratio (male to female) was 3.2, and the mean age was 66.3 (11.5). Among the 936 patients whose detailed clinical information was obtained, 86.4% of the patients presented high serum immunoglobulin G4 levels (≥135 mg/dL), and 82.3% received steroid therapy.

CONCLUSIONS

The data represent the current clinical features of AIP in Japan.

[Autoimmune pancreatitis. Evidence based management guidelines of the Hungarian Pancreatic Study Group]

Autoimmune pancreatitis is a rare disease which can even mimic pancreatic tumor, however, unlike the latter, it requires not surgical but conservative management. Correct diagnosis and differential diagnosis of autoimmune pancreatitis and treatment of these patients requires up-to-date and evidence based management guidelines. The Hungarian Pancreatic Study Group proposed to prepare an evidence based guideline based on the available international guidelines and evidences. The preparatory and consultation task force appointed by the Hungarian Pancreatic Study Group translated and complemented and/or modified the international guidelines if it was necessary. 29 relevant clinical questions in 4 topics were defined (Basics; Diagnosis; Differential diagnostics; Therapy). Evidence was classified according to the UpToDate(®) grading system. The draft of the guidelines was presented and discussed at the consensus meeting on September 12, 2014. All clinial questions were accepted with almost total (more than 95%) agreement. The present guideline is the first evidence based autoimmune pancreatitis guideline in Hungary. The guideline may provide very important and helpful data for tuition of autoimmune pancreatitis, for everyday practice and for establishing proper finance. Therefore, the authors believe that these guidelines will widely become a basic reference in Hungary.

Comparison of endoscopic retrograde cholangiopancreatography with papillary biopsy and endoscopic ultrasound-guided pancreatic biopsy in the diagnosis of autoimmune pancreatitis

BACKGROUND

International consensus diagnostic criteria (ICDC) have been proposed for the diagnostic criteria and algorithm of autoimmune pancreatitis (AIP). Although endoscopy is important in the diagnosis of AIP, practical patterns of its usage vary considerably worldwide. This study aimed to compare endoscopic retrograde cholangiopancreatography (ERCP) with papillary biopsy and endoscopic ultrasound (EUS)-guided pancreatic biopsy for diagnosing AIP using ICDC.

METHODS

We retrospectively reviewed and classified 165 Korean patients diagnosed by Korean criteria from June 2007 to October 2013. Among them, 61 patients underwent ERCP with duodenal papillary biopsy (group A) and 62 patients underwent EUS-guided pancreatic biopsy (group B). We analyzed the diagnostic criteria and levels of each criterion, and type of AIP before and after endoscopic procedures.

RESULTS

ERCP with papillary biopsy increased the diagnostic sensitivity from 65.6% (40/61) to 95.1% (58/61) (P < 0.01). EUS-guided pancreatic biopsy increased the diagnostic sensitivity from 50.0% (27/62) to 88.7% (55/62) (P < 0.01). The increases of diagnostic sensitivity in two endoscopic methods were not different statistically. In diagnosing definite AIP, EUS-guided pancreatic biopsy was more useful than ERCP with papilla biopsy (sensitivity; 79.0% vs. 65.6%, P < 0.01). EUS-guided pancreatic biopsy was helpful to classify type 1 and type 2 AIP in some patients. Procedure-related complication (mild pancreatitis) developed in one patient (1.6%) in group A and two patients (3.2%) in group B. ERCP with papillary biopsy was less expensive than EUS-guided pancreatic biopsy.

CONCLUSIONS

Both ERCP with papillary biopsy and EUS-guided pancreatic biopsy are safe and play important roles in diagnosing AIP according to the ICDC.

Framework for interpretation of trypsin-antitrypsin imbalance and genetic heterogeneity in pancreatitis

Early intracellular premature trypsinogen activation was interpreted as the key initiator of pancreatitis. When the balance in the homeostasis of trypsin and antitrypsin system is disequilibrated, elevated aggressive enzymes directly attack the pancreatic tissue, which leads to pancreatic destruction and inflammation. However, trypsin alone is not enough to cause complications in pancreatitis, which may play a crucial role in modulating signaling events in the initial phase of the disease. NFκB activation is the major inflammatory pathway involved in the occurrence and development of pancreatitis and it can be induced by intrapancreatic activation of trypsinogen. Synthesis of trypsinogen occurs in endoplasmic reticulum (ER), and ER stress is an important early acinar cell event. Components of ER stress response are known to be able to trigger cell death as well as NFκB signaling cascade. The strongest evidence supporting the trypsin-centered theory is that gene mutations, which lead to the generation of more trypsin, or reduce the activity of trypsin inhibitors or trypsin degradation, are associated with pancreatitis. Thus, trypsin-antitrypsin imbalance may be the first step leading to pancreatic autodigestion and inducing other pathways. Continued experimental studies are necessary to determine the specific relationships between trypsin-antitrypsin imbalance and genetic heterogeneity in pancreatitis. In this article, we review the latest advances that contributed to the understanding of the basic mechanisms behind the occurrence and development of pancreatitis with a focus on the interpretation of trypsin-antitrypsin imbalance and their relationships with other inflammation pathways. We additionally highlight genetic predispositions to pancreatitis and possible mechanisms associated with them.

Endoscopic approaches for the diagnosis of autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is characterized by diffuse pancreatic enlargement and irregular narrowing of the main pancreatic duct (MPD). Immunoglobulin (Ig)G4-related sclerosing cholangitis (IgG4-SC) associated with AIP frequently appears as a bile duct stricture. Therefore, it is important to differentiate AIP and IgG4-SC from pancreatic cancer and cholangiocarcinoma or primary sclerosing cholangitis, respectively. Endoscopy plays a central role in the diagnosis of AIP and IgG4-SC because it provides imaging of the MPD and bile duct strictures as well as the ability to obtain tissue samples for histological evaluations. Diffuse irregular narrowing of MPD on endoscopic retrograde cholangiopancreatography (ERCP) is rather specific to AIP, but localized narrowing of the MPD is often difficult to differentiate from MPD stenosis caused by pancreatic cancer. A long stricture (>1/3 the length of the MPD) and lack of upstream dilatation from the stricture (<5 mm) might be key features of AIP on ERCP. Some cholangiographic features, such as segmental strictures, stric tures of the lower bile duct, and long strictures with prestenotic dilatation, are more common in IgG4-SC than in cholangiocarcinoma. Endoscopic ultrasonography (EUS) reveals diffuse hypoechoic pancreatic enlargement, sometimes with hypoechoic inclusions, in patients with AIP. In addition, EUS-elastography and contrast-enhanced harmonic EUS have been developed with promising results. The usefulness of EUS-guided fine-needle aspiration has been increasingly recognized for obtaining adequate tissue samples for the histological diagnosis of AIP. Further improvement of endoscopic procedures and devices will contribute to more accurate diagnosis of AIP and IgG4-SC.

Diagnosis of autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a distinct form of chronic pancreatitis that is increasingly being reported. The presentation and clinical image findings of AIP sometimes resemble those of several pancreatic malignancies, but the therapeutic strategy differs appreciably. Therefore, accurate diagnosis is necessary for cases of AIP. To date, AIP is classified into two distinct subtypes from the viewpoints of etiology, serum markers, histology, other organ involvements, and frequency of relapse: type 1 is related to IgG4 (lymphoplasmacytic sclerosing pancreatitis) and type 2 is related to a granulocytic epithelial lesion (idiopathic duct-centric chronic pancreatitis). Both types of AIP are characterized by focal or diffuse pancreatic enlargement accompanied with a narrowing of the main pancreatic duct, and both show dramatic responses to corticosteroid. Unlike type 2, type 1 is characteristically associated with increasing levels of serum IgG4 and positive serum autoantibodies, abundant infiltration of IgG4-positive plasmacytes, frequent extrapancreatic lesions, and relapse. These findings have led several countries to propose diagnostic criteria for AIP, which consist of essentially similar diagnostic items; however, several differences exist for each country, mainly due to differences in the definition of AIP and the modalities used to diagnose this disease. An attempt to unite the diagnostic criteria worldwide was made with the publication in 2011 of the international consensus diagnostic criteria for AIP, established at the 2010 Congress of the International Association of Pancreatology (IAP).

Autoimmune pancreatitis: role of endoscopy in diagnosis and treatment

This review addresses the role of endoscopy in the diagnosis and treatment of autoimmune pancreatitis (AIP) and provides a diagnostic process for patients with suspected AIP. When should AIP be suspected? When can it be diagnosed without endoscopic examination? Which endoscopic approaches are appropriate in suspected AIP, and when? What are the roles of diagnostic endoscopic retrograde pancreatography, endoscopic biopsies, and IgG4 immunostaining? What is the proper use of the steroid trial in the diagnosis of AIP in patients with indeterminate computed tomography imaging? Should biliary stenting be performed in patients with AIP with obstructive jaundice?