Autoimmune pancreatitis: Current perspectives.

Over the last two decades, our knowledge and understanding regarding the pathogenesis and biology of autoimmune pancreatitis (AIP) have improved tremendously. Type 1 AIP or IgG4-related pancreatitis (IgG4-RP) is now believed to be the prototype of the multisystemic IgG4-related disease. In view of clinical features like obstructive jaundice and mass-forming lesions in the pancreas in elderly men, type 1 AIP often mimics pancreatic cancer. IgG4-related sclerosing cholangitis concomitantly involving the extrahepatic and intrahepatic biliary tree is the most common extrapancreatic involvement seen in up to 80% of these patients, which needs to distinguish from cholangiocarcinoma. Histology is characterised by lymphoplasmacytic inflammation, abundant IgG4 positive plasma cell infiltration, storiform fibrosis and obliterative phlebitis. Apart from histology, high serum IgG4 levels, pancreatic parenchymal and duct imaging findings and other organ involvement aid in diagnosis especially in cases where definitive histology is not evident. Also, these parameters lay the foundation of various diagnostic criteria proposed over last few years. On the contrary, histology alone is the mainstay for establishing diagnosis of idiopathic duct-centric pancreatitis (IDCP) as it lacks any specific serological marker or imaging. Since both types of AIP respond dramatically to corticosteroid treatment, a biopsy is crucial to establish the preoperative diagnosis and to exclude malignancy so as to avoid unnecessary surgery. This review discusses the morphologic spectrum, treatment and prognosis of IgG4-RP and IDCP with an emphasis on approach to diagnosis with relevant histologic features, differential diagnoses and the challenges faced during biopsy interpretation.

Feasibility and usefulness of endoscopic ultrasonography-guided shear-wave measurement for assessment of autoimmune pancreatitis activity: a prospective exploratory study.

PURPOSE: To assess the feasibility and the clinical usefulness of a newly developed endoscopic ultrasonography (EUS) shear-wave elastography technique (EUS shear-wave measurement: EUS-SWM) in the diagnosis and treatment of autoimmune pancreatitis (AIP). METHODS: Tissue elasticity was measured in the pancreas in 160 patients. The success rate of EUS-SWMs, the velocity of the shear wave (Vs, m/s), and the reliability index of the Vs measurement (VsN) were evaluated, and the elasticity (median Vs) was compared between AIP patients (n = 14) and normal controls. RESULTS: A total of 3837 EUS-SWMs were performed without adverse events. Overall, 97.6% (3743/3837) were successful. The median VsN was 74%. The median Vs values of the pancreas were as follows: 2.22 m/s in the pancreatic head (push position), 2.36 m/s in the head (pull position), 1.99 m/s in the body, and 2.25 m/s in the tail. The median Vs of the AIP group (2.57 m/s) was significantly higher than that of the normal controls (1.89 m/s) (P = 0.0185). The mean Vs significantly decreased from 3.32 m/s to 2.46 m/s after steroid therapy (n = 6) (P = 0.0234). CONCLUSION: EUS-SWM is feasible and generates credible results. EUS-SWM was a useful method for assessment of the effect of steroid therapy in AIP patients.

The Propagation Display Method Improves the Reproducibility of Pancreatic Shear Wave Elastography.

Evaluation of the pancreatic elastic modulus (PEM) using shear wave elastography (SWE) requires at least 5 measurements to ensure reproducibility. The aim of this study was to evaluate improvement in reproducibility of SWE, using the propagation display method in normal pancreas ([NP] phase 1) and to examine the differences in PEM between NP and chronic pancreatitis (CP), intraductal papillary mucinous neoplasm (IPMN) and autoimmune pancreatitis ([AIP] phase 2). In phase 1, the measurement success rate, median PEM in repeated measurements and appropriate number of SWE measurements were determined in 109 cases with NP. In phase 2, PEM was measured in CP (n = 10), IPMN (n = 31) and AIP (n = 5), using the required number of SWE measurements determined in phase 1. In phase 1, the measurement success rate was 93.9% (92/109 cases). The median PEM for NP was 14.6 kPa and the appropriate number of SWE measurements was at least 3. In phase 2, the median PEMs in CP, IPMN and AIP were 19.6, 18.1 and 17.2 kPa, respectively, with significant differences between NP and CP (p = 0.0133) and between NP and IPMN (p = 0.0436). Use of the propagation display method in SWE improves the reproducibility of measurement of PEM.

Pancreatitis autoinmune: desafío diagnóstico y tratamiento actual / Autoimmune pancreatitis: diagnostic challenges and current treatment

Autoimmune pancreatitis (AIP) is an inflammatory disease of the pancreas. The mechanism of the disease is not completely known. However, AIP shows cellular and humoral immunity elements, the most important being helper and regulatory T lymphocytes as well as B-lymphocytes and plasmocytes, participating in the fibroinflammatory process. Two histologic types have been described with different clinical characteristics. Type 1 AIP is part of a systemic condition associated with an increase of IgG4, while type 2 is a pancreatic disease, frequently associated with inflammatory bowel disease. From the clinical point of view, a third category is described when the classification is not possible at the moment of the diagnosis. The most important differential diagnosis of AIP is pancreatic cancer and it can be difficult, because current diagnostic methods used, including biopsy, have low specificity and sensitivity. AIP patients recover rapidly after steroid therapy, which can be useful even in differential diagnosis. Long-term prognosis is good: more than half of type 1 and almost all cases of type 2 patients have favorable outcome without recurrence and without severe consequences.

La pancreatitis autoinmune (PAI) es una enfermedad inflamatoria del páncreas. El mecanismo fisiopatológico no es completamente conocido. Sin embargo, presenta elementos de inmunidad celular y humoral, siendo de mayor importancia los linfocitos T-helper, T-reguladores, linfocitos B y plasmocitos, que participan en el desarrollo de la enfermedad. Se reconocen dos tipos histológicos con características clínicas también distintas. El tipo 1 forma parte de una enfermedad sistémica relacionada a aumento de IgG4, mientras el tipo 2 es una enfermedad pancreática, aunque con frecuencia asociada a enfermedad inflamatoria intestinal. Desde el punto de vista clínico, existe una tercera categoría, que se presenta cuando en el momento del diagnóstico de PAI la tipificación clínicamente no es posible. El diagnóstico diferencial más importante de la PAI es el cáncer de páncreas y puede ser clínicamente difícil. Los métodos actuales de diagnóstico incluyen la biopsia pero tienen un rendimiento bajo. La PAI responde rápidamente al tratamiento con esteroides, hecho que puede ser útil aún en el diagnóstico diferencial. Su pronóstico a largo plazo es bueno: más de la mitad de los casos tipo 1 y casi todos los casos tipo 2 evolucionan sin recaída y sin consecuencias graves a largo plazo.