PurposeAs a result of various independently proposed nomenclatures and classifications, there is confusion in the diagnosis and prediction of biological behavior of gastroenteropancreatic neuroendocrine tumors (GEP-NETs). A comprehensive nationwide study is needed in order to understand the biological characteristics of GEP-NETs in Korea.Materials and MethodsWe collected 4,951 pathology reports from 29 hospitals in Korea between 2000 and 2009. Kaplan-Meier survival analysis was used to determine the prognostic significance of clinicopathological parameters.ResultsAlthough the GEP-NET is a relatively rare tumor in Korea, its incidence has increased during the last decade, with the most significant increase found in the rectum. The 10-year survival rate for well-differentiated endocrine tumor was 92.89%, in contrast to 85.74% in well differentiated neuroendocrine carcinoma and 34.59% in poorly differentiated neuroendocrine carcinoma. Disease related death was most common in the biliary tract (62.2%) and very rare in the rectum (5.2%). In Kaplan-Meier survival analysis, tumor location, histological classification, extent, size, mitosis, Ki-67 labeling index, synaptophysin expression, lymphovascular invasion, perineural invasion, and lymph node metastasis showed prognostic significance (p<0.05), however, chromogranin expression did not (p=0.148). The 2000 and 2010 World Health Organization (WHO) classification proposals were useful for prediction of the prognosis of GEP-NET.ConclusionThe incidence of GEP-NET in Korea has shown a remarkable increase during the last decade, however, the distribution of tumors in the digestive system differs from that of western reports. Assessment of pathological parameters, including immunostaining, is crucial in understanding biological behavior of the tumor as well as predicting prognosis of patients with GEP-NET.

UC patients with PSC show a propensity for more extensive, but less active, disease but are otherwise characterized by similar pathologic findings compared with UC patients without PSC. Rectal sparing and patchy disease activity is not characteristic of UC patients with PSC.

Multiple gastrointestinal stromal tumors (GISTs) are extremely rare and usually associated with type 1 neurofibromatosis and familial GIST. The aim of this study was to investigate the clinical, phenotypic, and genetic characteristics of multiple GISTs to gain insights into their underlying pathogenesis and clinical behavior. Forty-seven paraffin blocks of multiple GISTs from 12 patients were analyzed. Genomic DNA was extracted from the tumor and normal mucosa and mutations for 4 exons of KIT gene and 3 exons of PDGFRA gene were determined. Among 12 patients with multiple GISTs, 5 were sporadic, 2 were familial with germline mutations of KIT gene, and 5 were associated with type 1 neurofibromatosis. All but 1 sporadic and familial multiple GISTs showed mutations of KIT gene shared by the same mutation on each GIST mass within a patient. But in 1 sporadic case, different types of KIT mutations were observed. Two familial multiple GIST cases showed diffuse involvement of the gastrointestinal tract with diffuse hyperplasia of interstitial cell of Cajal. Multiple GISTs associated with type 1 neurofibromatosis were located in the jejunum and harbored no mutations of KIT or PDGFRA. Different types of KIT gene mutation found in our case raise a possibility that recurrence of GISTs within a gastrointestinal tract may have a chance to be a rare occurrence of multiple primary GISTs instead of true recurrence. Multiple GISTs show unique clinical, phenotypic, and genotypic characteristics that are dependent on the particular underlying mechanisms, but the overall prognosis is favorable regardless of the numbers or phenotype of GISTs.

Our results suggest that cyclin D1 overexpression may be an early event in hepatocarcinogenesis and that it plays a role in tumor differentiation. In addition, cyclin D1 expression is not correlated with tumor cell proliferation in HCCs.

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