A Clinicopathologic Study Of Cystic And Solid Tumors Of Pancreas And The Analysis Of β-catenin Mutation

Objective This study aimed to study the clinicopathologic characteristics, differentiation patterns and histogenesis of cystic and solid tumors of the pancreas(CSTP) and to exproe 6-catenin mutation and expression and its relationship with tumorigenesis of CSTP.Methods (1)I5 cases of CSTP were studied using histologic(HE) , immunohistochemical (PV6000 )methods. (2)β-catenin Mutation Analysis on I5 cases of CSTP : DNA extraction was performed from formalin-fixed , paraffin-embedded tumor tissues. Genomic DNA from each CSTP was amplified by polymerase chain reaction (PCR) , direct DNA sequencing of β-catenin exon 3 , The expression of β-catenin were studed using immunohistochemical (PV6000 methods).Results (1)Clinical and imageology findings: I5 cases of CSTP were females, 18-51 years in age (mean 27.5 years).Of the 15 tumors, 5 cases were located in the head of the pancreas, 5 cases in the body, 4 cases in the tailand and 1 cases located in peritoneum. The mean diameter of tumors was 9. 6 cm (range, from 3 cm to 17.3 cm ).14 cases were well encapsulated by capsules. Computed tomographic (CT)examination revealed: variable combinations of solid portions and cystic areas in all 15 cases, 14 cases had a high density fibrous capsule. 1 cases had no clear margin .14 cases with follow up were free of desease (range , from 3 months to 10 years)after diagnosis, 1 cases with hepatic metastses was found no recurrence with follow-up 13 months(no treatment ).(2)Histologic finding : A uniform population of cells was seen . The nuclei were oval, round without alypia, and rate of mitotic activity was evident1 Psudopapillary structure with a fibrovascular core was remarkable Hemorrhage, foam cells and cholesterol crystals were often found. (3)Immunohistochemically:15 cases were were positive fora 1-AT;13 cases expressed vimentin, 10 cases expressed NSE, 9 cases expressed PDX-1,5 cases expressed CgA, 8 cases expressed PR, 4 cases expressed Actin, but all cases were negative for ER, Syn, EMA, Glucagon, Gastrin, Insulin.(4)Upon direct DNA sequencing of exon 3 of the β-catenin gene, 12 (80%) of the 15 CSTPs showed 1-bp missense mutation in codons 32 (5 cases), 33 (3 cases), 37 (4cases). On immunohistochemistry, 13 cases (86.7%)tested showed diffuse nuclear positivity for β-catenin.Conclusions (1)CSTP is a distinct clinicopathologic entity in young female patients with a benign clinical course. (2) CSTP develops from primitive pancreatic cells, with the potentiality of developing into ducts, acinus, and endocrine cells.(3) β-catenin mutations and nuclear accumulation may play an important role in the tumorigenesis of CSTP.