Contrast Enhanced Computed Tomography study of Cystic lesions of Pancreas with histopathological correlation .

Aims and objectives: To identify lesions with cystic appearance in pancreas, to differentiate between pancreatic cystic lesion of neoplastic etiology after exclusion of pseudocyst due to pancreatitis, to differentiate cystic lesion into benign and malignant nature based of CECT morphology, to correlate histopathological reports with CECT morphology. Materials and methods: It was a non-interventional prospective observational study in the department of radiology of Seth G.S. medical college and KEM hospital Mumbai.Patients meeting the inclusion criteria were studied over a period of 12 months. All patients who underwent contrast enhanced CT scan abdomen as advised by the respective physician/surgeon for further evaluation of already diagnosed pancreatic lesion or suspected cystic pancreatic lesionwere included in study. Results:We included 46 patients after application of inclusion and exclusion criteria and who underwent histopathological diagnostic procedure during follow up. Out of which 26 lesions turned out to be benign, 20 lesions showed malignant histopathology.After obtaining histopathological diagnosis of the lesion we studied CECT morphological criteria such aswall thickness, solid component,number of locules,size of cyst, largest locule size in multilocular cyst,pancreatic duct diameter. Out of 46 patients, there were 20 patients with unilocular cyst, 12 multilocular cysts,6 cases of IPMN (intraductal papillary mucinous neoplasm) and 6 cases of solid-cystic pancreatic lesions out of which 4 were adenocarcinoma and 2 were solid pseudopapillary neoplasm (SPEN). Out of 20 unilocular cysts, 12 were pseudocysts. Hence, 8 patients were considered as true unilocular cysts and were evaluated with CECT morphological criteria such as size of cyst, wall thickness of cyst and solid component within cyst. A size of <3cm showed benign nature and >3cm showed malignant potential of lesion. A wall thickness of <2mm or >2mm predicted benign and malignant nature of lesion respectively. A lesion with solid component <5mm or>5mmpredicted benign and malignant nature of lesion respectively. 14 patients of multilocular cystic lesions of pancreas were evaluated with criteria such as number of locules and size of locule. More than 6 locules was suggestive of benign nature and less than 6 locules predicted malignant nature.6 cases of IPMN were seen and all of them were malignant. Conclusion:The increasing use of Multidetector Computed Tomography has resulted in a marked increase in the incidental detection of cystic pancreatic lesions with advantages of improved spatial and contrast resolution have resulted in the differentiation of benign from malignant lesions. The purpose of this study was to address the diagnostic guidelines for the patients with cystic pancreatic lesions based on multiple morphological parameters of the cystic masses instead of conclusively interpreting any single criterion. The most important and significant result derived from the study rests in the use of wall thickness and absence of solid component criteria for the diagnosis of benign lesions. Conclusively stating, wall thickness less than 2mm and absence of solid component are diagnostic of benign cysts with a Positive predictive value of 100% and 95.8% respectively. The observation was made during the study that a unilocular cyst with wall thickness less than 2mm, size less than 3cm and absent solid component is almost always benign. For multilocular cysts which are usually mucinous, serous or IPMNs benign histopathology was predicted with 85.71% accuracyand by the presence of multiple locules (more than 6). The size of largest locules less than 2cm indicated benign nature with a similar accuracy.