Gorham-Stout Syndrome with Focal Segmental Glomerulosclerosis: A Case Report

Gorham-Stout syndrome is a rare bone disorder characterized by progressive massive osteolysis and proliferation of vascular and lymphatic vessels. A 15-year-old boy was initially diagnosed with Gorham-Stout at the age of 8 years based on clinical and radiological findings. Following diagnosis, he was treated with pamidronate, interferon alfa, propranolol, oral corticosteroids, and sirolimus. He developed proteinuria at the age of 15 and progressed into the nephrotic range 2 years later. A renal biopsy revealed focal segmental glomerulosclerosis, not otherwise specified variant. The sequential increase in proteinuria associated with medications suggested that the focal segmental glomerulosclerosis may be caused by pamidronate and sirolimus, but cannot completely rule out the possibility of kidney involvement of GSS itself.

Histologic and Molecular Pathogenesis of Gallbladder Cancer / 대한췌담도학회지

Adenocarcinoma is the major histology of gallbladder cancer. There are three subtypes of adenocarcinoma of the gallbladder: biliary, intestinal, and gastric foveolar subtypes. Also, there are three premalignant lesions of gallbladder adenocarcinoma: adenoma, biliary intraepithelial neoplasia (BilIN), and intracystic papillary neoplasm (ICPN). Premalignant lesion is hyperplasia of dysplastic epithelial cells with no evidence of stromal invasion. BilIN is invisible in gross inspection but can be microscopically identified around invasive tumor or chronic cholecystitis. ICPN is grossly identified as exophytic polypoid mass or diffuse friable thickening of mucosa and composed of mucinous epithelial cells with papillary and tubular arrangement. Dysplasia of BilIN and ICPN is classified by using a three-tiered system and high grade dysplasia is the same group with carcinoma in situ. Adenoma and ICPN have some ambiguities in definition and re-establishment of diagnostic criteria is needed for reproducibility of diagnosis. KRAS, TP53, and CDKN2A are the representative altered molecules in gallbladder cancer. Molecular alteration during dysplasia-carcinoma sequence is too heterogenous depending to the risk factors and type of premalignant lesion to explain the whole process by single process. Over-expression of COX2, mutation of TP53, impairment of mitochondrial DNA were reported in early hyperplastic or metaplastic epithelium. Loss of heterozygosity (LOH) of 3p, 8p chromosomes and amplification of HER2 were reported in low grade dysplasia and LOH of 9p, 18q, 22q, 17p chromosomes and mutation of CDK2A were reported in high grade dysplasia/carcinoma in situ.

Alteration of MRP2 expression and the graft outcome after liver transplantation

PURPOSE: Multidrug resistance-associated protein (MRP) 2 is a glutathione conjugate in the canalicular membrane of hepatocytes. Early graft damage after liver transplantation (LT) can result in alteration of MRP2 expression. The purpose of this study was to evaluate the relationship between the pattern of MRP2 alteration and graft outcome. METHODS: Forty-one paraffin-embedded liver graft tissues obtained by protocol biopsy within 2 months after LT; these were stained using monoclonal antibodies of MRP2. We selected 15 live donor biopsy samples as a control, that showed homogenous canalicular staining for MRP2. The pattern of canalicular MRP2 staining of graft was classified into 3 types: homogenous (type C0), focal (type C1), and no (type C2,) staining of the canaliculi. RESULTS: In total, 17.1% graft tissues were type C0, 36.6% were type C1, and 46.3% were type C2. The median operation time was longer in patients with type C2 (562.6 minutes) than in patients with type C0 (393.8 minutes) (P = 0.038). The rates of posttransplant complications were higher in patients with type C2 (100%) than in patients with type C0 (42.9%) and C1 (73.3%) (P < 0.001). CONCLUSION: MRP2 expression pattern was altered in 82.9% after LT. The pattern of MRP2 alteration was associated with longer operation time and higher rates of post-LT complications.

Comparison of the Clinicopathologic Characteristics of Intraductal Papillary Neoplasm of the Bile Duct according to Morphological and Anatomical Classifications

BACKGROUND: Intraductal papillary neoplasm of the bile duct (IPNB) is a recently defined entity and its clinical characteristics and classifications have yet to be established. We aimed to clarify the clinical features of IPNB and determine the optimal morphological classification criteria. METHODS: From 2003 to 2016, 112 patients with IPNB who underwent surgery were included in the analysis. After pathologic reexamination by a specialized biliary-pancreas pathologist, previously suggested morphological and anatomical classifications were compared using the clinicopathologic characteristics of IPNB. RESULTS: In terms of histologic subtypes, most patients had the intestinal type (n = 53; 48.6%) or pancreatobiliary type (n = 33; 30.3%). The simple “modified anatomical classification” showed that extrahepatic IPNB comprised more of the intestinal type and tended to be removed by bile duct resection or pancreatoduodenectomy. Intrahepatic IPNB had an equally high proportion of intestinal and pancreatobiliary types and tended to be removed by hepatobiliary resection. Morphologic classifications and histologic subtypes had no effect on survival, whereas a positive resection margin (75.9% vs. 25.7%; P = 0.004) and lymph node metastasis (75.3% vs. 30.0%; P = 0.091) were associated with a poor five-year overall survival rate. In the multivariate analysis, a positive resection margin and perineural invasion were important risk factors for survival. CONCLUSION: IPNB showed better long-term outcomes after optimal surgical resection. The “modified anatomical classification” is simple and intuitive and can help to select a treatment strategy and establish the proper scope of the operation.

A portable high-intensity focused ultrasound system for the pancreas with 3D electronic steering: a preclinical study in a swine model

PURPOSE: The aim of this animal study was to evaluate the safety and feasibility of a portable, ultrasonography-guided, high-intensity focused ultrasound (USg-HIFU) system to treat the pancreas. METHODS: Eight swine were included. Using a portable HIFU device (ALPIUS 900, Alpinion Medical Systems), ablations were performed on the pancreas in vivo. Different acoustic intensities were applied (1.7 kW/cm2 or 1.5 kW/cm2, n=2 [group A for a pilot study]; 1.5 kW/ cm2, n=3 [group B]; and 1.2 kW/cm2, n=3 [group C]). Magnetic resonance imaging (MRI) was performed immediately (group A) or 7 days (groups B and C) after HIFU treatment. In groups B and C, serum amylase and lipase levels were measured on days 0 and 7, and performance status was observed every day. Necropsy was performed on days 0 (group A) or 7 (groups B and C) to assess the presence of unintended injuries and to obtain pancreatic and peripancreatic tissue for histological analysis. RESULTS: Ablation was noted in the pancreas in all swine on MRI, and all pathologic specimens showed coagulation necrosis in the treated area. The mean ablation areas on MRI were 85.3±38.1 mm2, 90.7±21.2 mm2, and 54.4±30.6 mm2 in groups A, B, and C, respectively (P>0.05). No animals showed evidence of complications, except for one case of a pseudocyst in group B. CONCLUSION: This study showed that pancreas ablation using a portable USg-HIFU system may be safe and feasible, and that coagulation necrosis of the pancreas was successfully achieved with a range of acoustic intensities.

What Is Antibody-Mediated Rejection in Histologic Diagnosis in Liver Recipients? / 대한이식학회지

Antibody-mediated rejection (AMR) is a rare event in liver transplantation compared to other solid organs such as the kidney and heart because of the different immunologic reactions in the liver and it ability to compensate for damage. Although it is not easy to define the histological features that help diagnosis because of its rarity, a few histologic features such as portal eosinophilia with eosinophilic endothelialitis have been reported as useful for diagnosis of acute AMR in presensitized patients. C4d staining is not a good indicator of AMR in liver grafts because of its low sensitivity and specificity. AMR is an emerging cause of chronic graft failure, especially in high risk patients having preformed or de novo donor specific alloantibodies (DSA). Some histologic parameters including interface hepatitis, lobular inflammation, portal collagenation, portal venopathy, and sinusoidal fibrosis, have been suggested as chronic AMR to predict graft fibrosis and survival in DSA positive patients. In conclusion, recent studies have resulted in the histological diagnostic criteria of AMR becoming more specific; however, confirmation of AMR still requires strong clinical evidence for alloantibodies.

Prognosis of Hepatocellular Carcinoma after Liver Transplantation: Comparative Analysis with Partial Hepatectomy

BACKGROUND: Liver transplantation (LT) is the treatment of choice for hepatocellular carcinoma (HCC). The aim of this study was to investigate the recurrence rate of HCC after LT and prognostic factors for recurrence by comparing LT with non-transplanted resection. METHODS: The participants were 338 patients who underwent LT between 1996 and 2012 at Seoul National University Hospital (LT group) and 520 HCC patients who underwent partial hepatectomy between 1995 and 2006 (control group, non-LT group). RESULTS: In the LT group, 68 of 338 patients (19.8%) showed relapse, and the recurrence rate was lower than that in the non-LT group (64.9%, 357/520, p < .001). Stratification analysis by American Joint Committee on Cancer (AJCC) stage showed that the stage I-II LT group had a lower recurrence rate than the non-LT group. Univariate comparative analysis demonstrated that multiplicity of tumor, tumor size, gross type, Edmondson- Steiner (ES) nuclear grade, extent of tumor, angioinvasion, AJCC stage, Milan criteria, University of California at San Francisco criteria on explant pathology (all p < .001), positive expression of cytokeratin 19 (p = .002), and preoperative α-fetoprotein (AFP) (p < .001) were predictors of tumor recurrence. In multivariate analysis, LT, preoperative AFP, multiplicity of tumor, extent of tumor, size of tumor, and ES nuclear grade were independent prognostic factors. CONCLUSIONS: LT might have a protective effect against the late recurrence of stage I-II HCC compared to non-LT, and the prognostic factors for recurrence were similar to previously well-known prognostic factors for HCC.

False Positive Diagnosis of Hepatocellular Carcinoma in Liver Resection Patients

The diagnosis of hepatocellular carcinoma (HCC) is based on imaging studies particularly in high-risk patients without histologic confirmation. This study evaluated the prevalence and characteristics of false-positively diagnosed HCC in a liver resection cohort for HCC. A retrospective review was performed of 837 liver resection cases for clinically diagnosed HCC between 2005 and 2010 at our institute. High-risk patients with tumors > 1 cm with one or two image findings consistent with HCC and tumors 0.05) compared to non-HCC patients except for higher rate of history of alcoholism (P < 0.05) observed in non-HCC patients. Four of 18 non-HCC patients (22.2%) showed diagnostic discordance on the dynamic imaging study. Despite the recent progression in diagnostic imaging techniques, 2.2% of cases were false-positively diagnosed as HCC in a liver resection patient cohort; and the final diagnosis was benign disease in 0.8% of liver resection patients clinically diagnosed with HCC.

Survival outcome and prognostic factors of neoadjuvant treatment followed by resection for borderline resectable pancreatic cancer

PURPOSE: Neoadjuvant treatment may provide improved survival outcomes for patients with borderline resectable pancreatic cancer (BRPC). The purpose of this study is to evaluate the clinical outcomes of neoadjuvant treatment and to identify prognostic factors. METHODS: Forty patients who met the National Comprehensive Cancer Network definition of BRPC and received neoadjuvant treatment followed by surgery between 2007 and 2015 were evaluated. Prospectively collected clinicopathological outcomes were analyzed retrospectively. RESULTS: The mean age was 61.7 years and the male-to-female ratio was 1.8:1. Twenty-six, 3, and 11 patients received gemcitabine-based chemotherapy, 5-fluorouracil, and FOLFIRINOX, respectively. The 2-year survival rate (2YSR) was 36.6% and the median overall survival (OS) was 20 months. Of the 40 patients, 34 patients underwent resection and the 2YSR was 41.2% while the 2YSR of patients who did not undergo resection was 16.7% (P = 0.011). The 2YSR was significantly higher in patients who had partial response compared to stable disease (60.6% vs. 24.3%, P = 0.038), in patients who did than did not show a CA 19-9 response after neoadjuvant treatment (40.5% vs. 0%, P = 0.039) and in patients who did than did not receive radiotherapy (50.8% vs. 25.3%, P = 0.036). Five patients had local recurrence and 17 patients had systemic recurrence with a median disease specific survival of 15 months. CONCLUSION: Neoadjuvant treatment followed by resection is effective for BRPC. Pancreatectomy and neoadjuvant treatment response may affect survival. Effective systemic therapy is needed to improve long-term survival since systemic metastasis accounts for a high proportion of recurrence.

Undifferentiated embryonal sarcoma of the liver in an adult patient

Undifferentiated embryonal sarcoma of the liver (UESL) is rare primary hepatic sarcoma and is known to occur in pediatric patients. This case is the UESL occurred in a 51-year old male patient. Multilocular cystic lesion was composed of primitive spindle cells without specific differentiation. This rare case would help to review differential diagnosis of primary sarcoma in liver and cystic neoplasm of the liver.

Nuclear Expression of Hepatitis B Virus X Protein Is Associated with Recurrence of Early-Stage Hepatocellular Carcinomas: Role of Viral Protein in Tumor Recurrence

BACKGROUND: Hepatitis B virus (HBV) plays well-known roles in tumorigenesis of hepatocellular carcinoma (HCC) in infected patients. However, HBV-associated protein status in tumor tissues and the relevance to tumor behavior has not been reported. Our study aimed to examine the expression of HBV-associated proteins in HCC and adjacent nontumorous tissue and their clinicopathologic implication in HCC patients. METHODS: HBV surface antigen (HBsAg), HBV core antigen (HBcAg), and HBV X protein (HBx) were assessed in 328 HBV-associated HCCs and in 155 matched nontumorous tissues by immunohistochemistry staining. RESULTS: The positive rates of HBsAg and cytoplasmic HBx staining in tumor tissue were lower than those in nontumorous tissue (7.3% vs. 57.4%, p < .001; 43.4% vs. 81.3%, p < .001). Conversely, nuclear HBx was detected more frequently in tumors than in nontumorous tissue (52.1% vs. 30.3%, p < .001). HCCs expressing HBsAg, HBcAg, or cytoplasmic HBx had smaller size; lower Edmondson-Steiner (ES) nuclear grade, pT stage, and serum alpha-fetoprotein, and less angioinvasion than HCCs not expressing HBV-associated proteins. Exceptionally, nuclear HBx-positive HCCs showed higher ES nuclear grade and more frequent large-vessel invasion than did nuclear HBx-negative HCCs. In survival analysis, only nuclear HBx-positive HCCs had shorter disease-free survival than nuclear HBx-negative HCCs in pT1 and ES nuclear grade 1-2 HCC subgroup (median, 126 months vs. 35 months; p = .015). CONCLUSIONS: Our data confirmed that expression of normal HBV-associated proteins generally decreases in tumor cells in comparison to nontumorous hepatocytes, with the exception of nuclear HBx, which suggests that nuclear HBx plays a role in recurrence of well-differentiated and early-stage HCCs.

Histopathology of a benign bile duct lesion in the liver: Morphologic mimicker or precursor of intrahepatic cholangiocarcinoma

A bile duct lesion originating from intrahepatic bile ducts is generally regarded as an incidental pathologic finding in liver specimens. However, a recent study on the molecular classification of intrahepatic cholangiocarcinoma has focused on the heterogeneity of this carcinoma and has suggested that the cells of different origins present in the biliary tree may have a major role in the mechanism of oncogenesis. In this review, benign intrahepatic bile duct lesions—regarded in the past as reactive changes or remnant developmental anomalies and now noted to have potential for developing precursor lesions of intrahepatic cholangiocarcinoma—are discussed by focusing on the histopathologic features and its implications in clinical practice.

Diagnostic Accuracy of Endoscopic Ultrasound-Guided Fine Needle Aspiration Cytology of Pancreatic Lesions

BACKGROUND: Endoscopic ultrasound-guided fine needle aspiration cytology (EUS-FNAC) is currently the most commonly used procedure for obtaining cytologic specimens of the pancreas. It is accurate, minimally invasive, safe and cost-effective. However, there is discrepancy between cytological and surgical diagnoses. This study was aimed at evaluating the diagnostic accuracy of EUS-FNAC of the pancreas. METHODS: We performed a retrospective review of 191 cases of pancreatic lesions initially diagnosed by EUS-FNAC with subsequent histological diagnosis between 2010 and 2012 in the Department of Pathology, Seoul National University Hospital. Cytologic and surgical diagnoses were categorized into five groups: negative, benign, atypical, malignant, and insufficient for diagnosis. Subsequently, 167 cases with satisfactory yield in both surgical and cytology specimens were statistically analyzed to determine correlations with diagnosis. RESULTS: In comparison to surgical diagnoses, cytologic diagnoses were true-positive in 103 cases (61.7%), true-negative in 28 cases (16.8%), false-positive in 9 cases (5.4%), and false-negative in 27 cases (16.1%). The diagnostic accuracy was 78.4%, sensitivity was 79.2%, and specificity was 75.7%. The positive predictive value was 92.0%, and negative predictive value was 50.9%. CONCLUSIONS: EUS-FNAC has high accuracy, sensitivity, specificity and positive predictive value. Overcoming the limitations of EUS-FNAC will make it a useful and reliable diagnostic tool for accurate evaluation of pancreatic lesions.

Histopathologic factors affecting tumor recurrence after hepatic resection in colorectal liver metastases

PURPOSE: Hepatic resection is a standard method of treatment for colorectal liver metastases (CRLM). However, the pathologic factors of metastatic lesions that affect tumor recurrence are less well defined in CRLM. The aim of this study was to evaluate the risk factors for recurrence of CRLM, focusing on histopathologic factors of metastatic lesions of the liver. METHODS: From January 2003 to December 2008, 117 patients underwent curative hepatic resection for CRLM were reviewed. Tumor size and number, differentiation, tumor budding, angio-invasion, dedifferentiation and tumor infiltrating inflammation of metastatic lesions were investigated. RESULTS: The mean number of hepatic tumors was 2 (range, 1-8). The mean size of the largest tumor was 2.9 cm (range, 0.3-18.5 cm) in diameter. The moderate differentiation of the hepatic tumor was the most common in 86.3% of the patients. Tumor budding, angio-invasion, and dedifferentiation were observed in 81%, 34%, and 12.8% of patients. Inflammation infiltrating tumor was detected in 6.8% of patients. Recurrence after hepatic resection appeared in 69 out of 117 cases (58.9%). Recurrence-free survival at 1, 2 and 5 years were 62.4%, 43.6%, and 34.3%. The multivariate analysis showed the number of metastases > or =3 (P = 0.007), the tumor infiltrating inflammation (P = 0.047), and presence of dedifferentiation (P = 0.020) to be independent risk factors for tumor recurrence. CONCLUSION: Histopathological factors, i.e., dedifferentiation and tumor infiltrating inflammation of the metastatic lesion, could be one of the risk factors of aggressive behavior as well as the number of metastases even after curative resection for CRLM.

Sarcomatoid hepatocellular carcinoma with mixed osteoclast-like giant cells and chondroid differentiation

No abstract available.

CT Findings of Gallbladder Metastases: Emphasis on Differences According to Primary Tumors

OBJECTIVE: To describe computed tomography (CT) features of metastatic gallbladder (GB) tumors (MGTs) from various primary tumors and to determine whether there are differential imaging features of MGTs according to different primary tumors. MATERIALS AND METHODS: Twenty-one patients who had pathologically confirmed MGTs and underwent CT were retrospectively enrolled. Clinical findings including presenting symptoms, type of surgery, and interval between primary and metastatic tumors were recorded. Histologic features of primary tumor and MGTs including depth of invasion were also reviewed. Imaging findings were analyzed for the location and morphology of MGTs, pattern and degree of enhancement, depth of invasion, presence of intact overlying mucosa, and concordance between imaging features of primary and metastatic tumors. Significant differences between the histologies of MGTs and imaging features were determined. RESULTS: The most common primary tumor metastasized to the GB was gastric cancer (n = 8), followed by renal cell carcinoma (n = 4) and hepatocellular carcinoma (n = 3). All MGTs (n = 21) manifested as infiltrative wall thickenings (n = 15) or as polypoid lesions (n = 6) on CT, similar to the features of primary GB cancers. There were significant differences in the morphology of MGTs, enhancement pattern, enhancement degree, and depth of invasion according to the histology of primary tumors (p < 0.05). Metastatic adenocarcinomas of the GB manifested as infiltrative and persistently enhancing wall thickenings, while non-adenocarcinomatous metastases usually manifested as polypoid lesions with early wash-in and wash-out. CONCLUSION: Although CT findings of MGTs are similar to those of primary GB cancer, they are significantly different between the various histologies of primary tumors.

Rat Model of Hindlimb Ischemia Induced via Embolization with Polyvinyl Alcohol and N-Butyl Cyanoacrylate

OBJECTIVE: To investigate the feasibility of a rat model on hindlimb ischemia induced by embolization from the administration of polyvinyl alcohol (PVA) particles or N-butyl cyanoacrylate (NBCA). MATERIALS AND METHODS: Unilateral hindlimb ischemia was induced by embolization with NBCA (n = 4), PVA (n = 4) or surgical excision (n = 4) in a total of 12 Sprague-Dawley rats. On days 0, 7 and 14, the time-of-flight magnetic resonance angiography (TOF-MRA) and enhanced MRI were obtained as scheduled by using a 3T-MR scanner. The clinical ischemic index, volume change and degree of muscle necrosis observed on the enhanced MRI in the ischemic hindlimb were being compared among three groups using the analysis of variance. Vascular patency on TOF-MRA was evaluated and correlated with angiographic findings when using an inter-rater agreement test. RESULTS: There was a technical success rate of 100% for both the embolization and surgery groups. The clinical ischemic index did not significantly differ. On day 7, the ratios of the muscular infarctions were 0.436, 0.173 and 0 at thigh levels and 0.503, 0.337 and 0 at calf levels for the NBCA, PVA and surgery groups, respectively. In addition, the embolization group presented increased volume and then decreased volume on days 7 and 14, respectively. The surgery group presented a gradual volume decrease. Good correlation was shown between the TOF-MRA and angiographic findings (kappa value of 0.795). CONCLUSION: The examined hindlimb ischemia model using embolization with NBCA and PVA particles in rats is a feasible model for further research, and muscle necrosis was evident as compared with the surgical model.

The Histologic Cut-off Point for Adjacent and Remote Non-neoplastic Liver Parenchyma of Hepatocellular Carcinoma in Chronic Hepatitis B Patients

BACKGROUND: The molecular profile of peritumoral non-neoplastic liver parenchyma (PNLP) has recently been suggested as predictive factor of early and late recurrence of hepatocellular carcinoma (HCC). However, there is no definite cut-off point for tumor-free PNLP in terms of either histological or molecular changes. Therefore, our aim is to determine the numerical cut-off point for separating adjacent PNLP and remote PNLP in histopathologic perspective. METHODS: Peritumoral tissues from 20 resected HCC patients were sampled from 0 to 40 mm distance from the tumor border (divided into 5-mm columns). Histopathologic parameters such as necroinflammatory activity, fibrosis, bile ductular reaction, hepatic venulitis, peliosis, and steatosis were compared between each column. RESULTS: The morphologic changes just adjacent to the tumor were notably severe and faded with distance. The parenchyma within 10 mm of the tumor showed significantly severe inflammation, fibrosis, peliosis and hepatic venulitis compared with those from farther areas. The histopathologic changes of the parenchyma became stable beyond 20 mm. CONCLUSIONS: Results of this study revealed that the parenchyma within 10 mm distance from the tumor, or adjacent PNLP, has histopathologic changes that are directly affected by the tumor, and the parenchyma beyond 20 mm as the remote PNLP without tumor effect.

Myoepithelial hamartoma as a solitary mass in the pancreatic parenchyma: the first case report

Solid hamartoma of the pancreas is very rare, and only 3 cases have been reported thus far. A patient underwent pancreaticoduodenectomy due to a mass in the head of the pancreas which was suspected to be a borderline malignant tumor, but the histologic diagnosis turned out to be myoepithelial hamartoma (MEH) or adenomyoma. It was characterized by benign duct and glandular structures surrounded by proliferating smooth muscle, and acinus formation was not observed. Immunohistochemical stain for smooth muscle actin (SMA) was positive in spindle cells, and CD34 was negative, differentiating it from the three previously reported cases of solid hamartoma of the pancreas. MEH is an entity that is on the same spectrum as heterotopic pancreas. MEH is rare and has usually been reported in the gastrointestinal tract. To the best of our knowledge, MEH has never been reported in the pancreas. Therefore we report the world's first documented case of MEH of the pancreas.

Clinicopathologic Characteristics and Prognostic Factors of Nonfunctioning Endocrine Tumor of the Pancreas

PURPOSE: Nonfunctioning endocrine tumors of the pancreas have no specific symptoms. Therefore, diagnosis is usually delayed and the malignancy rate at the time of diagnosis is reported to be higher than 50%. However, it is difficult to discriminate malignant from benign nonfunctioning endocrine tumors preoperatively. The purpose of this study was to investigate clinical characteristics of nonfunctioning endocrine tumors of the pancreas, including predictive factors of malignancy and prognostic factors affecting long-term survival. METHODS: Between 1992 and 2010, clinicopathological data of 53 patients with nonfunctioning endocrine tumors proven by surgical pathology were reviewed retrospectively. RESULTS: Of the 53 patients, mean age was 54 years-old and the male to female ratio was 1:1.2 Median follow up was 32.1 months. At the time of diagnosis, liver metastasis was detected in 4 patients. Curative resection was achieved in 49 patients, and 17% of them had recurrence, which was most common in liver. The overall 5-year survival rate was 85.1%. Both the WHO classification (p<0.001) and AJCC staging (p<0.001) correlated well with long-term survival. Univariate analysis revealed preoperative body weight loss (p<0.001), weak enhancement at the early arterial phase (p=0.043), lymph node metastasis (p<0.001), liver metastasis (p=0.001), perineural invasion (p=0.001), or lymphovascular invasion (p=0.010) as prognostic factors. CONCLUSION: Nonfunctioning endocrine tumor of the pancreas has favorable survival outcomes. Lymph node metastasis (p<0.001), liver metastasis (p=0.001), perineural invasion (p=0.001), and lymphovascular invasion (p=0.010) are poor prognostic factors.