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

AIM:To investigate the usefulness of endoscopic ultrasound-guided fine needle aspiration(EUS-FNA) in the differentiation of autoimmune pancreatitis(AIP).METHODS:We retrospectively reviewed 47 of 56 AIP patients who underwent EUS-FNA and met the Asian diagnostic criteria.On 47 EUS-FNA specimens,we evaluated the presence of adequate material and characteristic features of lymphoplasmacytic sclerosing pancreatitis(LPSP) and idiopathic duct-centric pancreatitis(IDCP) mentioned in the International Consensus Diagnostic Criteria and examined if these findings make a contribution to the differential diagnosis of type 1 and type 2 AIP.A disposable 22-gauge needle was used for EUS-FNA.RESULTS:Adequate specimens including pancreatic tissue for differentiating AIP from cancer were obtained from 43 of 47 patients who underwent EUSFNA.EUS-FNA was performed from the pancreatic head in 21 cases,which is known to be technically difficult when performed by core biopsy;there was no significant difference in the results compared with pancreatic body-tail.Nine of 47 patients met level 1 findings of LPSP and 5 patients met level 2 findings of LPSP.No one met level 1 findings of IDCP,but 3 patients met level 2 findings of IDCP.Of 10 seronegative cases,2 cases were diagnosed with "definitive type 1 AIP",and 3 cases were diagnosed with "probable type 2 AIP" when considering both the level 2 histological findings and response to steroids.CONCLUSION:EUS-FNA is useful in the differentiation of type 1 and type 2 AIP,particularly in seronegative cases.

Clinical oncology for pancreatic and biliary cancers:Advances and current limitations

In the early 2000s,the main stream of endoscopic ultrasonography(EUS)changed from a mechanical scanning method to electronic radial or linear scanning methods.Subsequently,useful applications in trans-abdominal ultrasonography came within reach of EUS.In particular,contrast-enhanced EUS(CE-EUS)and EUS-elastography became cutting-edge diagnostic modalities for pancreatic disorders.Each type of pancreatic disorder has characteristic hemodynamics.CE-EUS uses color Doppler flow imaging and harmonic imaging to classify pancreatic lesions.EUS-elastography can assess tissue hardness by measuring its elasticity.This parameter appears to correlate with the malignant potential of the lesions.Tissue elasticity studies can provide information on both its pattern and distribution.The former is the conventional method of morphological diagnosis,but it is restricted to observations made in a region of interest(ROI).The latter is an unbiased analysis that can be performed by image analysis software and is theoretically constant,regardless of the ROI.Though EUSfine needle aspiration(FNA)is also a very useful diagnostic tool,there are several limitations.Diagnostic EUS-FNA of pancreatic cystic lesions has marginal utility mainly due to low sensitivity.Therefore,in particular,endoscopists should keep this limitation in mind.