The Study Of Imaging Of Intraductal Papillary Mucinous Tumor Of Pancreas

To study the relationship between gene promoter methylationchanges associated with 6 candidate tumor suppressor genes andneoplastic evolution and progression of intraductal papillary mucinoustumor (IPMT) of the pancreas, and analyze its clinical andcharacteristic radiological features comparing with pathologic resultthen discuss the value of 4 methods in diagnosing IPMT. Material and Methods 1. Study of gene promoter methylation changes in intraductalpapillary mucinous tumor (IPMT) of the pancreas. we examinedIPMTs from 25 patients for abnormal gene promoter hypermethylationassociated with p16, p73, APC, hMLH1, MGMT, E-cadherin by themethod of MSP further modified as a nested two-step approach inorder to increase the sensitivity. 2. Characteristic radiological features of intraductal papillarymucinous tumor: comparison with pathological findings. Fifty caseswith IPMT who underwent CT and MRI with contrast enhancementbefore operation were reviewed. We assessed clinical presentation andcharacteristic imaging findings comparison with clinical andpathological findings, and study the difference in the clinical andradiological features of malignant and benign tumors.3. Study of ultrasound, ERCP, CT and MRCP for diagnosingintraductal papillary mucinous tumor. Twenty-five patients who werereferred for operation with IPMT of the pancreas were included in thisstudy. We assessed the advantage and limitations of ultrasound, ERCP,CT and MRCP in diagnosing IPMT.Results4. we found aberrant methylation involving at least one genepromoter site in 92% of IPMT and no promoter methylation wasdetected for any of the candidate tumor suppressor genes among thedisease-free margins. The genes responsible for cell cycle control (p16,p73, APC), hypermethylation of each gene locus was found in everytumor. DNA repair genes (MGMT and hMLH1) were methylated in80% of invasive carcinomas. Hypermethylation of E-cadherin wasfound in 60% of invasive carcinomas. Hypermethylation involvingthree or more promoter regions was present in invasive carcinomas. Incomparison, IPMT-associated invasive adenocarcinomas showeddifference from CIS, P<0.05.5. Typical imaging findings of main duct type are segmental ordiffuse dilation of MPD with enhanced mural nodules after contrastmedium administration. Branch duct type was more frequently locatedin the head or uncinate. Typical imaging findings of branch duct typeare unilocular or multilocular cystic tumors with septa and/or muralnodules. The MPD involvement shows the dilatation of MPD.Comparing with pathologic findings we found that accumulation ofmucus is the result of dilatation of main duct and branch duct. Muralnodules were papillary projections which were composed of variabletissues including adenocarcinoma, adenoma and hyperplasia.Septawas composed of columnar epithelium and when the septashows irregular thickening, it may be highly suggestive of malignancy.The malignant and benign type of IPMT showed difference in theclinical and radiological features, P<0.05。6. Slight dilatation of MPD, unilocular or multilocular cystictumors, protruding papilla of Vater with expulsion of mucus are seenin benign IPMT. Obvious dilatation of MPD, cystic and solid lesionswith lager mural nodules and septa enhanced, abnormal protrudingpapilla of Vater with expulsion of mucus, dilatation of bile duct wereseen in malignant IPMT.MRCP can reveal the structure andcommunication between tumor and the MPD.Conclusion1. The results reflect a combination between tumor suppressorgene promoter methylation changes and the unique behavior of IPMT.Hypermethylation of three or more promoter regions is useful methodto diagnose malignant IPMT.2. Certain features may suggest the diagnosis of IPMT. Oldermale, Larger size of cyst and mural nodule, degree of dilatation of theMPD, and accompany with soft tissue mass may be helpful factors indetermining malignancy. Main duct type with older male or jaundice,and branch duct type of tumors bigger than 25 mm may be helpfulfactors in determining malignancy and should be operated.3. Malignant and benign IPMT showed different image featureson US, ERCP, CT and MRCP. MR cholangiopancreatography (MRCP)is a noninvasive and useful method to detect and definite diagnosis ofIPMT.