To Differentiate Focal Autoimmune Pancreatitis From Pancreatic Cancer by Endoscopic Ultrasound

Study Overview
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Brief Summary
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Autoimmune pancreatitis (AIP) is a special type of chronic pancreatitis mediated by autoimmunity. The classic manifestation of AIP is diffuse pancreatic enlargement, some of which are characterized by focal enlargement. Clinically, it is divided into diffuse AIP (DAIP) and focal AIP (FAIP) according to morphology. FAIP can be clinically manifested as obstructive jaundice, peripancreatic lymphadenopathy and vascular involvement, which may mimic pancreatic cancer (PC). CT/MRI is the important imaging tool for diagnosing pancreatic diseases. However, due to the overlap of the imaging features of FAIP and PC, it is challenging to differentiate the two by CT/MRI. Endoscopic ultrasound (EUS) can clearly display the pancreatic parenchyma and pancreatic duct system and has become a routine modality for the evaluation of pancreatic diseases. The aim of this study is to construct a diagnosis model for distinguishing between FAIP and PC by comparing the EUS characteristics of the two, and further validate its diagnostic efficacy.

Detailed Description
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A derivation sample is established by retrospectively collecting the EUS images of about 100 FAIP patients and about 200 PC patients who were diagnosed for the first time in Peking Union Medical College Hospital in the past 6 years and underwent EUS at the same time. The parenchymal and ductal changes of pancreas were defined according to the Rosemont criteria. The parenchymal characteristics included hyperechoic foci/strands and lobularity, and the ductal changes included main pancreatic duct (MPD) dilation. Other EUS characteristics not included in the conventional criteria were described based on the literatures, including pancreatic diffuse hypoechogenicity, focal hypoechogenicity, pancreatic diffuse enlargement, focal enlargement, peripancreatic hypoechoic margin, common bile duct (CBD) dilation, bile duct wall thickening, lymphadenopathy and vessel involvement. The EUS characteristics of the two groups of patients are included in the multivariate stepwise logistic regression and receiver operating characteristics (ROC) analyses to construct a differential diagnosis model in derivation sample. Further, the differential diagnosis model will be prospectively validated by calculating the sensitivity and specificity in about 90 patients who are going to undergo EUS due to the difficulty in distinguishing between FAIP and PC. Diagnosis of AIP meets the revised Mayo clinic criteria (revised HISORt criteria) including features of histology, imaging, serology, other organs involvement and response to steroid therapy. Diagnosis of pancreatic duct adenocarcinoma is confirmed by surgical pathology or by cytology/histology after EUS-guided fine needle aspiration or biopsy.

Official Title
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Construction and Validation of a Diagnosis Model Based on Endoscopic Ultrasound Characteristics for Differentiating Between Focal Autoimmune Pancreatitis and Pancreatic Cancer

Conditions
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Autoimmune Pancreatitis, Pancreatic Cancer

Intervention / Treatment
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* Other: Diagnostic imaging modalities for validation sample
* Other: EUS for derivation sample


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with difficulty in distinguishing between FAIP and PC Exclusion Criteria: Referred patients with a history of having being conclusively diagnosed as AIP or PC; Patients with DAIP; Patients with alcoholic pancreatitis, hypertriglyceridemia pancreatitis or pancreatitis due to gallstones; Patients with pancreatic cystic tumors, pancreatic neuroendocrine tumors or solid pseudopapillary tumors of pancreas; Patients who cannot undergo EUS due to unsuitable conditions.

Ages Eligible for Study
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Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Derivation sample<br>The patients conclusively diagnosed as FAIP or PC are retrospectively collected. | Other: EUS for derivation sample<br>* Endoscopic ultrasound was performed.<br>|
| Validation sample<br>The patients with difficulty in distinguishing between FAIP and PC are prospectively enrolled. | Other: Diagnostic imaging modalities for validation sample<br>* Endoscopic ultrasound and other imaging modalities such as CT, MRI, or PET-CT are performed.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To construct a diagnosis model for distinguishing FAIP from PC and further validate its efficacy | Score is assigned to each predictor based on the odd ratio (OR) value, individual risk is estimated based on the sum of weighted score for each predictor and optimal cut-off point is obtained based on receiver operating characteristic (ROC) analysis. Sensitivity and specificity were used to assess the diagnostic efficacy. | 1 week after the diagnosis is conclusive | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Compare the efficacy of EUS based on the model with that of CT/MRI/PET-CT in differentiating between FAIP and PC | Sensitivity and specificity were used to assess the diagnostic efficacy | 1 week after the diagnosis is conclusive |