Irregular narrowing of the main pancreatic duct in association with a wall thickening is a key sign at endoscopic ultrasonography for the diagnosis of autoimmune pancreatitis

The Role of Endoscopic Ultrasound and Ancillary Techniques in the Diagnosis of Autoimmune Pancreatitis: A Comprehensive Review

Autoimmune pancreatitis (AIP) is a unique form of chronic pancreatitis with a multifactorial pathogenesis. Historically, it has been classified as type 1 and type 2, according to its clinical and histological features. The diagnosis of AIP is challenging and relies on a combination of clinical, histopathologic, serologic, and imaging characteristics. In the available guidelines, the imaging hallmarks of AIP are based on cross-sectional imaging and cholangiopancreatography retrograde endoscopic findings. Endoscopic ultrasound (EUS) is generally used for pancreatic tissue acquisition to rule out pancreatic cancer and diagnose AIP with limited accuracy. Several papers reported the reliability of EUS for providing informative morphologic features of AIP. Nowadays, the improvement in the resolution of EUS conventional images and the development of new ancillary technologies have further increased the diagnostic yield of EUS: contrast-enhanced EUS and EUS elastography are non-invasive and real-time techniques that strongly support the diagnosis and management of pancreatic diseases. In this review article, we will present the role of conventional EUS and ancillary diagnostic techniques in the diagnosis of AIP to support clinicians and endosonographers in managing this condition.

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.

Differential EUS findings in focal type 1 autoimmune pancreatitis and pancreatic cancer: A proof-of-concept study

Background and Objectives:

Autoimmune pancreatitis (AIP) often mimics pancreatic cancer (PC), particularly if presenting as a focal lesion. EUS may orient the differential diagnosis between them. This study aims to identify EUS findings that might be useful to differentiate type 1 focal autoimmune pancreatitis (f-AIP1) and PC.

Materials and Methods:

F-AIP1 and PC patients were retrospectively collected, matched, and compared. EUS findings considered were: focal mass echogenicity, loss of lobularity, distal atrophy, peripancreatic hypoechoic margins (PHM), pancreatic duct dilation, duct-penetrating sign (DPS), pancreatic/common bile duct thickened walls (PD/CBD-TW), and vessel infiltration (VI). Elastography findings were also recorded. Variables with a P < 0.05 at univariate analysis were included in logistic multiple regression.

Results:

Fifteen patients with f-AIP and 60 with PC were studied. FE was hypoechoic in all patients from both groups. PHM was observed in 40% of f-AIP1 cases but not in PC ones (P < 0.001). DPS was found in 10/15 (66.7%) f-AIP1 and in 7/60 (11.7%) PC patients (P < 0.001). PD-TW and CBD-TW were observed in 66.7%/60% f-AIP1 cases and in 6.7%/13.6% PC patients, respectively (P < 0.001 for both comparisons). Pancreatic masses were significantly different at EUS elastography (elastic respectively in 71.4% f-AIP1 and 3.8% PC, P < 0.001). VI was suspected in 20% of f-AIPs and 85% of PCs (P < 0.001). At multiple regression, PD-TW, CBD-TW, elastic pattern, and the absence of VI independently supported a diagnosis of f-AIP1.

Conclusions:

Our results suggest that EUS findings deserve consideration in the diagnostic workup of AIP to improve the differential diagnosis with PC.

A resected case of focal autoimmune pancreatitis with pancreatic duct wall thickening representing periductal lymphoplasmacytic infiltrate

This case revealed that branch pancreatic duct wall thickening by endoscopic ultrasonography represented periductal lymphoplasmacytic infiltrate as a characteristic histopathological finding of autoimmune pancreatitis, which may help in the diagnosis of autoimmune pancreatitis. An 80-year-old man was referred because fluorodeoxyglucose-positron emission tomography for lung cancer indicated abnormal uptake in the pancreatic head. Computed tomography showed an enhanced mass with cystic structures in the pancreatic head. Magnetic resonance cholangiopancreatography revealed mild dilatation of the main pancreatic duct in the pancreatic body with no strictures. Endoscopic ultrasonography demonstrated a lobulated heterogeneous hypoechoic mass in the pancreatic head. A branch pancreatic duct with wall thickening connected the mass to the main pancreatic duct. An intraductal neoplasm filling and spreading into the branch pancreatic duct was considered, and surgery was performed. Histopathologically, the mass consisted of marked inflammatory cell infiltration, storiform fibrosis, and obliterative phlebitis. The branch pancreatic duct with wall thickening revealed a band-like inflammatory cell infiltration with mainly lymphocytes and plasma cells beneath the normal pancreatic duct epithelium. Immunohistological staining revealed abundant IgG4-positive plasma cells (> 10 cells/HPF) in the inflammatory cell infiltration. The definite diagnosis was type 1 focal autoimmune pancreatitis.

The role of EUS in diagnosing focal autoimmune pancreatitis and differentiating it from pancreatic cancer

Background and Objectives:

The clinical presentation of focal autoimmune pancreatitis (FAIP) and together with radiological overlap can mimic pancreatic cancer (PC). The aim of this study is to construct and validate a prediction model for differentiating FAIP from PC according to EUS characteristics.

Patients and Methods:

Ninety patients with FAIP and 196 patients with PC, who consecutively underwent EUS at our center from January 2013 to December 2018, were retrospectively included in the study. The enrolled patients were randomly divided into either a derivation sample or a validation sample. According to EUS characteristics, multivariate stepwise logistic regression and receiver operating characteristics (ROC) analyses were used to construct a prediction model in derivation sample, and then, the efficacy was assessed in validation sample.

Results:

EUS characteristics that were suggestive of FAIP included diffuse hypoechogenicity, hyperechoic foci/stands or lobularity (parenchymal heterogeneity), bile duct wall thickening and peripancreatic hypoechoic margin; and EUS features favoring PC included focal hypoechogenicity, absence of parenchymal heterogeneity, pancreatic duct dilation, and vessel involvement. The prediction model, with an area under the ROC curve of more than 0.95, had a good capability to distinguish FAIP from PC. By using the optimal cutoff value, the efficacy of model for diagnosing PC showed 83.7%–91.8% sensitivity and 93.3%–95.6% specificity.

Conclusions:

It is feasible to differentiate FAIP from PC based on EUS characteristics. The prediction model built in this study needs to be further confirmed by multicenter prospective researches.

Pancreatic and biliary tract involvement in IgG4-related disease

The diagnosis and treatment of pancreatic and biliary tract involvement in IgG4 disease can be challenging for physicians. A French series shows that the pancreas is the most frequently involved organ in systemic IgG4 disease. Pancreatitis may be found in more than 50% of patients with IgG4 disease and the biliary tract is involved in one third. Pancreatic or biliary involvement may be isolated, metachronous or synchronous of other IgG4-related organ injuries. Pancreatitis related to IgG4 disease is called autoimmune pancreatitis (AIP) type 1. The diagnosis is mainly suspected in the presence of symptoms and morphological features. Changes observed on conventional imaging are not typical and are usually similar to lesions observed in autoimmune pancreatitis type 2. AIP type 1 can also sometimes have a clinical or morphological presentation that mimics pancreatic cancer, especially pseudo-tumoral forms, associated with obstructive jaundice, weight loss and fatigue. Thus, the first challenge is to confirm the diagnosis of autoimmune pancreatitis and to exclude cancer. The AIP type must then be determined to decide on the most appropriate treatment.

Pancreatic Cytology

The diagnostic approach to pancreaticobiliary disease requires a multidisciplinary team in which the cytopathologist plays a crucial role. Fine-needle aspiration, obtained by endoscopic ultrasound, is the diagnostic test of choice for pancreatic lesions. Preoperative clinical management depends on many factors, many of which rely on accurate cytologic assessment. Pancreaticobiliary cytology is wrought with diagnostic pitfalls. Clinical history, imaging studies, cytology samples, and ancillary tests, including immunohistochemistry, biochemical analysis, and genetic sequencing, are integral to forming a complete diagnosis and guiding optimal patient management. This article reviews clinical aspects and the diagnostic work-up of commonly encountered diagnostic entities within the field of pancreatic cytology.

Features of Autoimmune Pancreatitis Associated With Inflammatory Bowel Diseases

BACKGROUND & AIMS

Few people know of autoimmune pancreatitis (AIP), a rare disorder associated with inflammatory bowel diseases (IBD). We aimed to describe phenotype and outcomes of IBD and AIP when associated.

METHODS

We performed a retrospective study of cases of AIP in IBD identified from the multicenter Groupe d'Etude Thérapeutique des Affections Inflammatoires du tube Digestif in Belgium and France from July 2012 through July 2015. Patients were diagnosed with AIP based on the International Consensus Diagnostic Criteria for AIP. A definitive AIP diagnosis was based on histological analysis of pancreatic resection specimens or samples collected by fine-needle aspiration during endoscopic ultrasound. Patients with probable type 1 AIP were identified based on imaging findings, clinical and/or radiologic responses to steroids, level of serum immunoglobulin G4, and involvement of other organs. Patients with probable type 2 AIP were identified based on imaging findings, clinical and/or radiologic responses to steroids, and association with IBD. The primary objective was to collect information on the characteristics of AIP in patients with IBD. We also compared features of patients with IBD with and without AIP in a case-control analysis, using multivariate analysis.

RESULTS

We analyzed data from 91 individuals with AIP and IBD (47 women) seen at 23 centers (58 had ulcerative colitis [UC] and 33 Crohn's disease [CD]). Eighty-nine patients had type 2 AIP, and 2 patients had type 1 AIP. The mean age at diagnosis of AIP was 35 ± 12 years, and for IBD it was 32 ± 12 years. AIP preceded IBD in 19 patients (21%). Over a mean follow-up period of 5.7 ± 4.9 years, 31 patients (34%) relapsed, 11 patients (12%) developed diabetes, and 17 patients (19%) developed exocrine pancreatic insufficiency. In patients with UC, factors independently associated with AIP included proctitis (odds ratio [OR], 2.9; 95% confidence interval [CI], 1.3-6.3; P = .007) and colectomy (OR, 7.1; 95% CI, 2.5-20; P = .0003). In patients with CD, AIP was significantly associated with fewer perianal lesions (OR, 0.16; 95% CI, 0.03-0.77; P = .023), non-stricturing non-penetrating CD (OR, 6.7; 95% CI, 1.25-33.3; P = .0029), and higher rate of colectomy (OR, 27.8; 95% CI, 3.6-217; P = .0029).

CONCLUSIONS

In a multicenter retrospective analysis of patients with AIP and IBD, followed for an average of 5.7 ± 4.9 years, we found most to have type 2 AIP. Two-thirds of patients have UC, often with proctitis. One-third of patients have CD, often with inflammatory features. Patients with IBD and AIP have higher rates of colectomy than patients with just IBD.

Recent developments in steroid-responsive pancreatitides (autoimmune pancreatitis)

PURPOSE OF REVIEW

There are two distinct steroid responsive chronic fibro-inflammatory diseases of the pancreas, called type 1 and type 2 autoimmune pancreatitis (AIP). We review recent progress in this field.

RECENT FINDINGS

It has recently been suggested that the term AIP be used to describe type 1 AIP and the term idiopathic duct-centric chronic pancreatitis (IDCP) be used for type 2 AIP. Clinical features and long-term outcomes of AIP and IDCP are well characterized and prognosis of both diseases is excellent. Diagnostic strategies tailored to regional practice patterns have emerged with the application of International Consensus Diagnostic Criteria for AIP. Although corticosteroids remain the mainstay of treatment, management of relapses and strategies for preventing multiple relapses are better understood, including the role of maintenance therapy and B-cell depletion therapy with rituximab. Association studies with malignancies have yielded conflicting results regarding risk of cancer in AIP.

SUMMARY

The treatment, follow-up guidelines and associations continue to evolve with our increasing experience with both AIP and IDCP. In AIP, rituximab can be used for both induction and maintenance of remission. IDCP responds to steroids without need for maintenance therapy. Both AIP and IDCP have excellent prognosis.