Pancreatic neuroendocrine tumors: radiographic calcifications correlate with grade and metastasis

[Imaging of pancreatic neuroendocrine tumors]

BACKGROUND

Neuroendocrine tumors of the pancreas have a broad biological spectrum. The treatment decision is based on an optimal diagnosis with regard to the local findings and possible locoregional and distant metastases. In addition to purely morphologic imaging procedures, functional parameters are playing an increasingly important role in imaging.

OBJECTIVES

Prerequisites for optimal imaging of the pancreas, technical principles are provided, and the advantages and disadvantages of common cross-sectional imaging techniques as well as clinical indications for these special imaging methods are discussed.

MATERIALS AND METHODS

Guidelines, basic and review papers will be analyzed.

RESULTS

Neuroendocrine tumors of the pancreas have a broad imaging spectrum. Therefore, there is a need for multimodality imaging in which morphologic and functional techniques support each other. While positron emission tomography/computed tomography (PET/CT) can determine the presence of one or more lesions and its/their functional status of the tumor, magnetic resonance imaging (MRI) efficiently identifies the location, relationship to the main duct and the presence of liver metastases. CT allows a better vascular evaluation, even in the presence of anatomical variants as well as sensitive detection of lung metastases.

CONCLUSIONS

Knowledge of the optimal combination of imaging modalities including clinical and histopathologic results and dedicated imaging techniques is essential to achieve an accurate diagnosis to optimize treatment decision-making and to assess therapy response.

Synchronous neuroendocine liver metastases in comparison to primary pancreatic neuroendocrine tumors on MRI and SSR-PET/CT

Background

The study aimed to compare and correlate morphological and functional parameters in pancreatic neuroendocrine tumors (pNET) and their synchronous liver metastases (NELM), while also assessing prognostic imaging parameters.

Methods

Patients with G1/G2 pNET and synchronous NELM underwent pretherapeutic abdominal MRI with DWI and 68Ga-DOTATATE/TOC PET/CT were included. ADC (mean, min), SNR_art and SNT_T2 (SNR on arterial phase and on T2) and SUV (max, mean) for three target NELM and pNET, as well as tumor-free liver and spleen (only in PET/CT) were measured. Morphological parameters including size, location, arterial enhancement, cystic components, T2-hyperintensity, ductal dilatation, pancreatic atrophy, and vessel involvement were noted. Response evaluation used progression-free survival (PFS) with responders (R;PFS>24 months) and non-responders (NR;PFS ≤ 24 months).

Results

33 patients with 33 pNETs and 95 target NELM were included. There were no significant differences in ADC and SUV values between NELM and pNET. 70% of NELM were categorized as hyperenhancing lesions, whereas the pNETs exhibited significantly lower rate (51%) of hyperenhancement (p<0.01) and significant lower SNR_art. NELM were qualitatively and quantitatively (SNR_T2) significantly more hyperintense on T2 compared to pNET (p=0.01 and p<0.001). NELM of R displayed significantly lower ADCmean value in comparison to the ADC mean value of pNET (0.898 versus 1.037x10-3mm²/s,p=0.036). In NR, T2-hyperintensity was notably higher in NELM compared to pNET (p=0.017). The hepatic tumor burden was significantly lower in the R compared to the NR (10% versus 30%).

Conclusions

Arterial hyperenhancement and T2-hyperintensity differ between synchronous NELM and pNET. These findings emphasize the importance of a multifaceted approach to imaging and treatment planning in patients with these tumors as well as in predicting treatment responses.

Usefulness of intratumoral perfusion analysis for assessing biological features of non-functional pancreatic neuroendocrine neoplasm

PURPOSE

Here, we evaluated the usefulness of intratumoral perfusion analysis using preoperative contrast-enhanced CT (E-CT) to assess biological features of non-functional pancreatic neuroendocrine neoplasms (NF-PanNENs).

METHODS

We retrospectively studied 44 patients who underwent curative surgery for NF-PanNENs. We used preoperative E-CT with compartment model analysis to calculate the tumor perfusion parameters K1 (inflow rate constant), 1/k2 (mean transit time), and K1/k2 (distribution volume). We assessed the association between perfusion parameters and biological features of NF-PanNENs, including the WHO classification tumor histopathological grade and prognosis after surgery.

RESULTS

Patients in this study had a neuroendocrine tumor (NET) G1 (n = 32) or NET G2 (n = 12). Neither NET G3 or NEC tumors were observed. Among perfusion parameters, K1 was the most accurate predictor of the high-grade tumor (AUC: 0.726). K1-low (< 0.028 s-1) was significantly associated with large tumors (≥ 20 mm) (p = 0.022), high mitotic index (p = 0.017), high Ki-67 index (p = 0.004), and lymphatic invasion (p = 0.025). Synchronous extra-pancreatic metastasis, including lymph node metastasis or liver metastasis, more frequently developed in K1-low patients than in K1-high patients (29% vs 4%, p = 0.025). Disease-free survival of patients with a K1-low tumor was poorer than that of patients with a K1-high tumor (p = 0.005). Furthermore, no patient with a K1-high tumor developed recurrence after initial surgery.

CONCLUSION

The perfusion parameters obtained using E-CT were significantly associated with biological features and prognosis of NF-PanNENs.

Long-term Follow-up of Small Nonfunctioning Pancreatic Neuroendocrine Tumors Diagnosed Using Endoscopic Ultrasound-guided Fine-needle Aspiration

Objective Clinical practice guidelines in Japan recommend surgery for all nonfunctioning pancreatic neuroendocrine tumors (NF-PNETs), regardless of their size or associated symptoms. Because pancreatic resection is highly invasive, follow-up for small NF-PNETs is often chosen in clinical practice. However, the natural history of NF-PNET remains poorly understood. We aimed to examine the natural history of pathologically confirmed NF-PNET. Methods This single-center retrospective case series investigated NF-PNETs that were pathologically diagnosed using endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) at our hospital between 2014 and 2018. Patients who were followed up without treatment due to their general condition or their wish were included in the study. Patients' background characteristics, imaging findings, pathological findings, and long-term prognoses were investigated using medical records. Results Overall, 26 patients were diagnosed with NF-PNET by EUS-FNA during the observation period. Of these, 9 patients (3 men and 6 women; median age: 64 years old) were followed up without treatment. All of these patients were asymptomatic, and localization was noticed in 3 cases in the head, body, and tail (1 each), with a median size of 12 (range: 4-18) mm. Neuroendocrine tumor (Grade 1 [G1]) was pathologically diagnosed in all patients with EUS-FNA. The median observation period was 63 (range: 26-90) months. Tumor growth and distant metastasis were not observed in any of the nine patients who remained asymptomatic. Conclusion Follow-up is a feasible option for asymptomatic NF-PNET ≤20 mm in size with a pathological grade of G1.

Approaching Small Neuroendocrine Tumors with Radiofrequency Ablation

In recent years, small pancreatic neuroendocrine tumors (pNETs) have shown a dramatic increase in terms of incidence and prevalence, and endoscopic ultrasound (EUS) radiofrequency ablation (RFA) is one potential method to treat the disease in selected patients. As well as the heterogeneity of pNET histology, the studies reported in the literature on EUS-RFA procedures for pNETs are heterogeneous in terms of ablation settings (particularly ablation powers), radiological controls, and radiological indications. The aim of this review is to report the current reported experience in EUS-RFA of small pNETs to help formulate the procedure indications and ablation settings. Another aim is to evaluate the timing and the modality of the radiological surveillance after the ablation. Moreover, new studies on large-scale series are needed in terms of the safety and long-term oncological efficacy of RFA on these small lesions.

Calcifications and Cystic Morphology on Preoperative Imaging Predict Survival After Resection of Pancreatic Neuroendocrine Tumors

BACKGROUND

Radiographic calcifications and cystic morphology are associated with higher and lower tumor grade, respectively, in pancreatic neuroendocrine tumors (PNETs). Whether calcifications and/or cystic morphology could be used preoperatively to predict post-resection survival in patients with PNETs remains elusive.

METHODS

Patients undergoing curative-intent resection of well-differentiated PNETs from 2000 to 2017 at eight academic institutions participating in the US Neuroendocrine Tumor Study Group were identified. Preoperative cross-sectional imaging reports were reviewed to identify the presence of calcifications and of a cystic component occupying >50% of the total tumor area. Clinicopathologic characteristics and recurrence-free survival (RFS) were compared.

RESULTS

Of 981 patients studied, 18% had calcifications and 17% had cystic tumors. Tumors with calcifications were more commonly associated with Ki-67 ≥3% (47% vs. 33%; p = 0.029), lymph node metastasis (36% vs. 24%; p = 0.011), and distant metastasis (13% vs. 4%; p < 0.001). In contrast, cystic tumors were less commonly associated with lymph node metastasis (12% vs. 30%; p < 0.001). Five-year RFS after resection was most favorable for cystic tumors without calcifications (91%), intermediate for solid tumors without calcifications (77%), and least favorable for any calcified PNET (solid 69%, cystic 67%; p = 0.043). Calcifications remained an independent predictor of RFS on multivariable analysis (p = 0.043) controlling for nodal (p < 0.001) and distant metastasis (p = 0.001).

CONCLUSIONS

Easily detectable radiographic features, such as calcifications and cystic morphology, can be used preoperatively to stratify prognosis in patients with PNETs and possibly inform the decision to operate or not, as well as guide the extent of resection and potential use of neoadjuvant therapy.

Prediction of Pathological Grades of Pancreatic Neuroendocrine Tumors Based on Dynamic Contrast-Enhanced Ultrasound Quantitative Analysis

Objective: To investigate whether the dynamic contrast-enhanced ultrasound (DCE-US) analysis and quantitative parameters could be helpful for predicting histopathologic grades of pancreatic neuroendocrine tumors (pNETs). Methods: This retrospective study conducted a comprehensive review of the CEUS database between March 2017 and November 2021 in Zhongshan Hospital, Fudan University. Ultrasound examinations were performed by an ACUSON Sequioa unit equipped with a 3.5 MHz 6C−1 convex array transducer, and an ACUSON OXANA2 unit equipped with a 3.5 MHz 5C−1 convex array transducer. SonoVue® (Bracco Inc., Milan, Italy) was used for all CEUS examinations. Time intensity curves (TICs) and quantitative parameters of DCE-US were created by Vuebox® software (Bracco, Italy). Inclusion criteria were: patients with histopathologically proved pNETs, patients who underwent pancreatic B-mode ultrasounds (BMUS) and CEUS scans one week before surgery or biopsy and had DCE-US imaging documented for more than 2 min, patients with solid or predominantly solid lesions and patients with definite diagnosis of histopathological grades of pNETs. Based on their prognosis, patients were categorized into two groups: pNETs G1/G2 group and pNETs G3/pNECs group. Results: A total of 42 patients who underwent surgery (n = 38) or biopsy (n = 4) and had histopathologically confirmed pNETs were included. According to the WHO 2019 criteria, all pNETs were classified into grade 1 (G1, n = 10), grade 2 (G2, n = 21), or grade 3 (G3)/pancreatic neuroendocrine carcinomas (pNECs) (n = 11), based on the Ki−67 proliferation index and the mitotic activity. The majority of the TICs (27/31) of pNETs G1/G2 were above or equal to those of pancreatic parenchyma in the arterial phase, but most (7/11) pNETs G3/pNECs had TICs below those of pancreatic parenchyma from arterial phase to late phase (p < 0.05). Among all the CEUS quantitative parameters of DCE-US, values of relative rise time (rPE), relative mean transit time (rmTT) and relative area under the curve (rAUC) were significantly higher in pNETs G1/G2 group than those in pNETs G3/pNECs group (p < 0.05). Taking an rPE below 1.09 as the optimal cut-off value, the sensitivity, specificity and accuracy for prediction of pNETs G3/pNECs from G1/G2 were 90.91% [58.70% to 99.80%], 67.64% [48.61% to 83.32%] and 85.78% [74.14% to 97.42%], respectively. Taking rAUC below 0.855 as the optimal cut-off value, the sensitivity, specificity and accuracy for prediction of pNETs G3/pNECs from G1/G2 were 90.91% [66.26% to 99.53%], 83.87% [67.37% to 92.91%] and 94.72% [88.30% to 100.00%], respectively. Conclusions: Dynamic contrast-enhanced ultrasound analysis might be helpful for predicting the pathological grades of pNETs. Among all quantitative parameters, rPE, rmTT and rAUC are potentially useful parameters for predicting G3/pNECs with aggressive behavior.

Contrast Enhanced EUS for Predicting Solid Pancreatic Neuroendocrine Tumor Grade and Aggressiveness

Pancreatic neuroendocrine tumor (PNET) behavior assessment is a daily challenge for physicians. Modern PNET management varies from a watch-and-wait strategy to surgery depending on tumor aggressiveness. Therefore, the aggressiveness definition plays a pivotal role in the PNET work-up. The aggressiveness of PNETs is mainly based on the dimensions and histological grading, with sometimes a lack of specificity and sensibility. In the last twenty years, EUS has become a cornerstone in the diagnostic phase of PNET management for its high diagnostic yield and the possibility of obtaining a histological specimen. The number of EUS applications in the PNET work-up has been rapidly increasing with new and powerful possibilities. The application of contrast has led to an important step in PNET detection; in recent years, it has been gaining interesting applications in aggressiveness assessment. In this review, we underline the latest experiences and opportunities in the behavior assessment of PNETs using contact-enhanced EUS and contested enhanced harmonic EUS with a particular focus on the future application and possibility that these techniques could provide.

The Evolving Landscape of Neuroendocrine Tumors

Neuroendocrine tumors (NETs) represent a heterogeneous group of tumors, with variable presentation based on the location of origin and degree of metastatic spread. There are no randomized control trials to guide surgical management; however, surgery remains the mainstay of treatment for most gastroenteropancreatic NETs based on retrospective studies. Metastatic disease is common at the time of presentation, particularly in the liver. There is a role for cytoreduction for improvement of both symptoms and survival. Robust prospective randomized data exists to support the use of medical therapies to improve progression-free and overall survival in patients with advanced, metastatic, and unresectable NETs.

Qualitative imaging features of pancreatic neuroendocrine neoplasms predict histopathologic characteristics including tumor grade and patient outcome

OBJECTIVES

To identify PanNEN imaging features associated with tumor grade and aggressive histopathological features.

METHODS

Associations between histopathological and imaging features of resected PanNEN were retrospectively tested. Histopathologic features included WHO grade, lymphovascular invasion (LVI), growth pattern (infiltrative, circumscribed), and intratumoral fibrosis (mature, immature). Imaging features included size, degree/uniformity of enhancement, progressive enhancement, contour, infiltrative appearance (infiltrative_im), calcifications, cystic components, tumor thrombus, vascular occlusion (VO), duct dilatation, and atrophy. Multinomial logistic regression analyses evaluated the magnitude of associations. Association of variables with outcome was assessed using Cox-proportional hazards regression.

RESULTS

133 patients were included. 3 imaging features (infiltrative_im, ill-defined contour [contour_ill], and VO) were associated with all histopathologic parameters and poor outcome. Increase in grade increased odds of contour_ill by 15.6 times (p = 0.0001, 95% CI 3.8-64.4). PanNEN with VO were 51.1 times (p = 0.0002, 6.5-398.6) more likely to demonstrate LVI. For PanNEN with contour_ill, infiltrative growth pattern was 51.3 times (p < 0.0001, 9.1-288.4), and fibrosis was 14 times (p = 0.0065, 2.1-93.7) more likely. Contour_ill was associated with decreased recurrence-free survival (p = 0.0003, HR 18.29, 3.83-87.3) and VO (p = 0.0004, HR6.08, 2.22-16.68) with decreased overall survival.

CONCLUSIONS

Infiltrative_im, contour_ill, and VO on imaging are associated with higher grade/histopathological parameters linked to tumor aggression, and poor outcome.

Clinical significance of pancreatic calcifications: a 15-year single-center observational study

Objectives

Pancreatic calcifications (PC) are considered specific for chronic pancreatitis (CP), but PC may also be present in non-CP diseases. The aims are to understand the pattern of calcifications in different diseases and to determine they were related to malignant diseases.

Methods

A retrospective study was performed including patients with PC or CP undergoing surgery in the Department of General Surgery of Ruijin Hospital from January 2003 to June 2018.

Results

PC were observed in 168 (4.5%) of the 3755 patients with pancreatic lesions treated during the study period. The majority of patients with PC had three kinds of CP (73.2%) while 26.8% had other five kinds of non-CP diseases. In patients with non-CP diseases, the incidence of PC in malignant intraductal papillary mucinous neoplasm (IPMN) was significantly higher than benign IPMN (8.3% vs. 0.7%, p = 0.004). In patients of CP with pancreatic mass (n = 81), PC (Odds ratio = 28.6, p = 0.000), advanced age (> 55 years) and parenchymal atrophy were independent predictors for malignancy. In patients of CP without pancreatic mass (n = 110), there were 82 cases (74.5%) with PC and 5 cases (4.5%) with pancreatic ductal adenocarcinoma. The regression model of risk factors was not successful.

Conclusions

The disease spectrum with PC was very diverse. PC may be related to malignant IPMN in non-CP diseases and is related to malignancy in the patients of CP with pancreatic mass and indications for resection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40001-022-00725-9.

Preoperative risk stratification of lymph node metastasis for non-functional pancreatic neuroendocrine neoplasm: An international dual-institutional study

BACKGROUND

/Objectives: Although the presence of lymph node metastasis (LNM) defines malignant potential, preoperative prediction of LNM has not been established for non-functional pancreatic neuroendocrine neoplasm (NF-PNEN). We sought to develop a prediction system using only preoperatively available factors that would stratify the risk of LNM for NF-PNEN.

METHODS

We retrospectively reviewed patients who underwent R0/1 resection of NF-PNEN at Kyoto University (2007-2019) and the University of California, San Francisco (2010-2019). Risk stratification of LNM was developed using preoperative factors by the logistic regression analysis. Long-term outcomes were compared across the risk groups.

RESULTS

A total of 131 patients were included in this study. Lymph nodes were pathologically examined in 116 patients, 23 (20%) of whom had LNM. Radiological tumor size [1.5-3.5 cm (odds ratio: 13.5, 95% confidence interval: 1.77-398) and >3.5 cm (72.4, 9.06-2257) against ≤1.5 cm], <50% cystic component (8.46 × 10^6, 1.68 × 10^106-), and dilatation of main pancreatic duct ≥5 mm (31.2, 3.94-702) were independently associated with LNM. When patients were classified as the low-risk (43 patients), intermediate-risk (44 patients), and high-risk groups (29 patients), proportions of LNM differed significantly across the groups (0%, 14%, and 59%, respectively). Recurrence-free survival (RFS) of the low- and intermediate-risk groups were significantly better than that of the high-risk group (5-year RFS rates of 92.2%, 85.4%, and 47.1%, respectively).

CONCLUSIONS

The prediction system using preoperative radiological factors stratifies the risk of LNM for NF-PNEN. This stratification helps to predict malignant potential and determine the surgical procedure and necessity of regional lymphadenectomy.

Management and outcomes of patients for non-functioning pancreatic neuroendocrine tumours: a multi-institutional analysis

BACKGROUND

To analysed the short- and long-term outcomes of patients who underwent surgical resection for non-functioning pancreatic neuroendocrine tumours (NF-PNETs) to gain insights into treatment approaches for this rare and heterogeneous entity.

METHODS

All patients who underwent surgical resection for NF-PNETs at The Second Affiliated Hospital of Guangzhou Medical University, and West China Hospital, Sichuan University, from 2009 to 2019 were retrospectively reviewed. The data of patients was including perioperative management, pathologic analysis and follow-up.

RESULTS

A total of 119 cases with histologically or cytologically confirmed NF-PNETs, The mean age of the patients was 52, and 56.3% were female. Twenty-three patients received post-operative adjuvant therapy, and five of nine (55.6%) patients with distant metastasis showed recurrence 14(60.9%) G2/G3 patients without distant metastasis received post-operative therapy with octreotide. Of these 14 patients, 3 (21.4%) revealed recurrence. Univariate analysis indicated that symptoms (P = 0.03), tumour size >4 cm (P = 0.029), ENETS stages III-IV (P < 0.001), positive lymph nodes (P < 0.001), vascular/perineural invasion (P < 0.001), and pathology grade G2 were associated with significantly higher risks of recurrence; age, gender, surgery type, and tumour location were not. Multivariate analysis revealed that positive lymph nodes (P < 0.001), vascular/peripheral invasion (P < 0.001), and pathology grade G3 (P = 0.03) are significant prognostic factors of tumour recurrence.

CONCLUSION

Positive lymph nodes, vascular/peripheral invasion and pathology grade G3 were related to recurrence of NF-PNETs. Lymph node resection is recommend when FNA biopsy indicates pathology grade G3 for patients with NF-PNETs.

Utility of contrast-enhanced harmonic endoscopic ultrasonography for predicting the prognosis of pancreatic neuroendocrine neoplasms

BACKGROUND AND AIMS

Pancreatic neuroendocrine neoplasms (PanNENs), including Grade 1 (G1) or G2 tumors, can have a poor prognosis. This study investigated the value of contrast-enhanced harmonic endoscopic ultrasonography (CH-EUS) for predicting the prognosis of PanNENs.

METHODS

This single-center, retrospective study included 47 consecutive patients who underwent CH-EUS and were diagnosed with PanNEN by surgical resection or EUS-guided fine needle aspiration between December 2011 and February 2016. Patients were divided into aggressive and non-aggressive groups according to the degree of clinical malignancy. CH-EUS was assessed regarding its capacity for diagnosing aggressive PanNEN, the correspondence between contrast patterns and pathological features, and its ability to predict the prognosis of PanNEN.

RESULTS

There were 19 cases of aggressive PanNEN and 28 cases of non-aggressive PanNEN. The aggressive group included three G1, four G2, three G3 tumors, three mixed neuroendocrine non-neuroendocrine neoplasms, and six neuroendocrine carcinomas. CH-EUS was superior to contrast-enhanced computed tomography for the diagnosis of aggressive PanNEN (P < 0.001): hypo-enhancement on CH-EUS was an indicator of aggressive PanNEN, with sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 94.7%, 100%, 100%, 96.6%, and 97.9%, respectively. Among G1/G2 PanNENs, cases with hypo-enhancement on CH-EUS had a poorer prognosis than those with hyper/iso-enhancement (P = 0.0009). Assessment of 36 resected specimens showed that hypo-enhancement on CH-EUS was associated with smaller and fewer vessels and greater degree of fibrosis.

CONCLUSION

Contrast-enhanced harmonic endoscopic ultrasonography may be useful for predicting the prognosis of PanNENs.

Effect of the transcription factor YY1 on the development of pancreatic endocrine and exocrine tumors: a narrative review

Pancreatic tumors are classified into endocrine and exocrine types, and the clinical manifestations in patients are nonspecific. Most patients, especially those with pancreatic ductal adenocarcinoma (PDAC), have lost the opportunity to receive for the best treatment at the time of diagnosis. Although chemotherapy and radiotherapy have shown good therapeutic results in other tumors, their therapeutic effects on pancreatic tumors are minimal. A multifunctional transcription factor, Yin-Yang 1 (YY1) regulates the transcription of a variety of important genes and plays a significant role in diverse tumors. Studies have shown that targeting YY1 can improve the survival time of patients with tumors. In this review, we focused on the mechanism by which YY1 affects the occurrence and development of pancreatic tumors. We found that a YY1 mutation is specific for insulinomas and has a role in driving the degree of malignancy. In addition, changes in the circadian network are a key causative factor of PDAC. YY1 promotes pancreatic clock progression and induces malignant changes, but YY1 seems to act as a tumor suppressor in PDAC and affects many biological behaviors, such as proliferation, migration, apoptosis and metastasis. Our review summarizes the progress in understanding the role of YY1 in pancreatic endocrine and exocrine tumors and provides a reasonable assessment of the potential for therapeutic targeting of YY1 in pancreatic tumors.

Differentiation between non-hypervascular pancreatic neuroendocrine tumors and mass-forming pancreatitis using contrast-enhanced computed tomography

BACKGROUND

Non-hypervascular pancreatic neuroendocrine tumors (PNETs) showed slight or iso-enhancement in contrast-enhanced computed tomography (CE-CT), which shared similar imaging findings with mass-forming pancreatitis (MFPs).

PURPOSE

To explore the value of CT imaging features in differentiating the two diseases.

MATERIAL AND METHODS

Fifty-one patients with histologically proved MFPs (n = 27) or non-hypervascular PNETs (n = 24) were included. Two radiologists reviewed CT imaging findings and clinical features. Logistic regression analysis was performed to identify relevant features in differentiating non-hypervascular PNETs and MFPs. Receiver operating characteristic (ROC) curve analysis was used to show the performance of the optimal parameters in differentiating non-hypervascular PNETs and MFPs.

RESULTS

A well-defined margin was more common in non-hypervascular PNETs (P < 0.05) than that in MFPs. MFPs often occurred in older people (P < 0.01) and the head-neck of the pancreas compared with non-hypervascular PNETs (P < 0.05). Metastases only presented in non-hypervascular PNETs (P < 0.05). CT values at venous phase and delay phase of MFPs were higher (P = 0.010 and P = 0.029) than those in non-hypervascular PNETs. Logistic analysis showed gender, tumor margin, CT values at venous phase, and tumor components were independent predictors in differentiating the two lesions. The area under the curve (AUC) was 0.938 with a sensitivity of 87.5% and specificity of 92.6% for combined predicators.

CONCLUSION

Gender, tumor margin, CT values at venous phase, and tumor components were useful predicators in differentiating non-hypervascular PNETs and MFPs.

Pancreatic Neuroendocrine Neoplasms: CT Spectral Imaging in Grading

RATIONALE AND OBJECTIVES

The purpose of this study was to define the CT spectral imaging characteristics of pancreatic neuroendocrine neoplasms (PNENs) and evaluate their potential for differential diagnosis of nonlow grade (non-LG) PNENs from low grade (LG) PNENs.

MATERIALS AND METHODS

CT spectral imaging data of 54 pathologically proven PNENs were retrospectively reviewed. Patients were divided into two groups: 40 cases with grade 1 in LG PNENs group and 14 cases with grade 2 and grade 3 in non-LG PNENs group.

RESULTS

Gender, calcification, inhomogeneity, invasiveness, PD dilatation, lymph node enlargement, size, normalized iodine (water) concentration in arterial phase (AP) (Iodine (ap)), normalized effective-Z (Z_ap), slope of normalized CT spectral curves in both AP, and portal venous phase were found to be significant variables for differentiating non-LG PNENs from LG PNENs (p < 0.05). Non-LG PNENs had larger size and lower Z_ap and Iodine (ap) than LG PNENs. The tumor size, Z_ap and Iodine (ap) had fair to good diagnostic performance with the area under receiver-operating-characteristic curve (AUC) 0.843, 0.733, and 0.728, respectively. Multivariate analysis with logistic regression had higher AUC (p<0.05) than all the single parameters except for size.

CONCLUSION

There were significant differences in CT spectral imaging parameters between non-LG and LG PNENs. Tumor size was the most promising independent parameter and the combination of quantitative parameters with qualitative parameters is the best predictor in differentiating of non-LG PNENs from LG PNENs. CT spectral imaging can help determine the malignancy of PNENs, which can better assist in surgical planning.

The Landmark Series: Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) comprise a heterogeneous group of neoplasms arising from pancreatic islet cells that remain relatively rare but are increasing in incidence worldwide. While significant advances have been made in recent years with regard to systemic therapies for patients with advanced disease, surgical resection remains the standard of care for most patients with localized tumors. Although formal pancreatectomy with regional lymphadenectomy is the standard approach for most PNETs, pancreas-preserving approaches without formal lymphadenectomy are acceptable for smaller tumors at low risk for lymph node metastases. Furthermore, observation of small, asymptomatic, low-grade PNETs is a safe, initial strategy and is generally recommended for tumors < 1 cm in size. In this Landmark Series review, we highlight the critical studies that have defined the surgical management of PNETs.

Pearls and pitfalls of imaging features of pancreatic cystic lesions: a case-based approach with imaging-pathologic correlation

A variety of neoplastic and non-neoplastic lesions of the pancreas can present with a predominantly cystic architecture. These lesions are increasingly being detected as incidental findings on routine cross-sectional imaging following technological advances in these techniques and their widespread use. The different histopathological behaviors show various common and uncommon imaging findings, and some cases show similar appearance in spite of different histopathology. Each lesion requires specific management because of the differing risk of progression to malignancy, and an accurate imaging diagnosis is crucial. The typical imaging characteristics that differentiate pancreatic cystic lesions have been well described and fully summarized. However, in addition to a small percentage of cases that shows uncommon imaging findings, a substantial percentage of cystic lesions shows overlapping imaging findings that can lead to radiological misdiagnosis. For appropriate diagnosis and optimal treatment strategy, it is important to know the uncommon and overlapping imaging findings of these lesions, in addition to familiarity with the typical aspects. In this article, we reconfirm the well-known characteristic imaging features of pancreatic cystic lesions and present several diagnostically challenging cases, focusing on the uncommon and overlapping imaging findings.

Surgical management of primary pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (PanNETs) are the second most common malignancy of the pancreas, and their incidence is increasing. PanNETs are a diverse group of diseases which range from benign to malignant, can be sporadic or associated with genetic mutations, and be functional or nonfunctional. In as much, the treatment and management of PanNETs can vary from a "Wait and See" approach to orthotopic liver transplantation (OLT). Despite this, surgical resection is still the primary treatment modality to achieve cure. This review focuses on the surgical management of PanNETs.

Radiographic characteristics of neuroendocrine liver metastases do not predict clinical outcomes following liver resection

Background

Previous research has demonstrated that specific radiographic criteria, including the presence of calcifications and the enhancement pattern on computed tomography (CT) imaging, correlates with clinicopathologic features and outcomes of patients with gastroenteropancreatic neuroendocrine tumors (NET). We sought to investigate whether these radiographic characteristics were prognostic among patients with neuroendocrine liver metastases (NELM) undergoing surgical resection.

Methods

The preoperative contrast-enhanced CT scans of all patients who underwent resection of NELM at a single institution between 2000-2015 were retrospectively reviewed. The presence of calcifications was determined on non-contrast phase imaging. Enhancement on the arterial phase scan was categorized as hyperenhancing, hypoenhancing, or mixed. Relevant clinicopathologic characteristics as well as recurrence-free survival (RFS) and overall survival (OS) were compared between groups.

Results

Among 82 patients who underwent resection of NELM, 57 had available data on calcifications while 51 had data available on arterial enhancement patterns. Among all patients, median age was 58 (IQR: 47-63) and the majority were female (N=48, 59.5%). The most common primary tumor locations were pancreas (N=25, 30.5%) and small bowel (N=27, 32.9%). The most commonly performed operations were right hepatectomy (N=29, 35.4%), bisegmentectomy (N=15, 18.3%), and segmentectomy (N=14, 17.1%). Median tumor number was 4 (IQR: 2-9), median Ki-67 was 5% (IQR: 2-10%), and median size of the largest liver metastasis was 4.5 (IQR: 2.8-7.7) cm. Twelve (21%) patients had tumor calcifications. Among patients with and without calcifications there were no differences in demographics, clinicopathologic characteristics, RFS (P=0.772) or OS (P=0.095). Arterial enhancement was hypoenhancing in 23 (45.1%), hyperenhancing in 10 (19.6%), and mixed in 18 (35.3%). Similarly, there were no differences between arterial enhancement groups in demographics, clinicopathologic characteristics, RFS (P=0.618) or OS (P=0.268).

Conclusions

Radiographic characteristics on contrast-enhanced CT are not associated with the outcomes of patients undergoing resection of NELM. Future investigations should evaluate the prognostic impact of functional neuroendocrine imaging.

Pancreatic neuroendocrine tumors

PURPOSE OF REVIEW

Pancreatic neuroendocrine tumors (pNETs) are a rare, heterogeneous group of pancreatic neoplasms with a wide range of malignant potential. They may manifest as noninfiltrative, slow-growing tumors, locally invasive masses, or even swiftly metastasizing cancers.

RECENT FINDINGS

In recent years, because of the increasing amount of scientific literature available for pNETs, the classification, prognostic stratification criteria, and available consensus guidelines for diagnosis and therapy have been revised and updated.

SUMMARY

The vast majority of new pNET diagnoses consist of incidentally discovered lesions on cross-sectional imaging. The biologic behavior of pNETs is defined by the grade and stage of the tumor. Surgery is the only curative treatment and it, therefore, represents the first therapeutic choice for any localized pNET; however, recent evidence suggests that patients with small (<2 cm), nonfunctioning G1 tumors can be safely observed.An aggressive surgical approach towards liver metastases is recommended in selected cases, as well as liver-directed therapies for disease control. In the presence of unresectable progressive disease, somatostatin analogs, targeted therapies such as everolimus, peptide receptor radionuclide therapy, and systemic chemotherapy are all useful tools for prolonging survival.

Leveraging machine learning techniques for predicting pancreatic neuroendocrine tumor grades using biochemical and tumor markers

BACKGROUND

The incidence of pancreatic neuroendocrine tumors (PNETs) is now increasing rapidly. The tumor grade of PNETs significantly affects the treatment strategy and prognosis. However, there is still no effective way to non-invasively classify PNET grades. Machine learning (ML) algorithms have shown potential in improving the prediction accuracy using comprehensive data.

AIM

To provide a ML approach to predict PNET tumor grade using clinical data.

METHODS

The clinical data of histologically confirmed PNET cases between 2012 and 2018 were collected. A method of minimum P for the Chi-square test was used to divide the continuous variables into binary variables. The continuous variables were transformed into binary variables according to the cutoff value, while the P value was minimum. Four classical supervised ML models, including logistic regression, support vector machine (SVM), linear discriminant analysis (LDA) and multi-layer perceptron (MLP) were trained by clinical data, and the models were labeled with the pathological tumor grade of each PNET patient. The performance of each model, including the weight of the different parameters, were evaluated.

RESULTS

In total, 91 PNET cases were included in this study, in which 32 were G1, 48 were G2 and 11 were G3. The results showed that there were significant differences among the clinical parameters of patients with different grades. Patients with higher grades tended to have higher values of total bilirubin, alpha fetoprotein, carcinoembryonic antigen, carbohydrate antigen 19-9 and carbohydrate antigen 72-4. Among the models we used, LDA performed best in predicting the PNET tumor grade. Meanwhile, MLP had the highest recall rate for G3 cases. All of the models stabilized when the sample size was over 70 percent of the total, except for SVM. Different parameters varied in affecting the outcomes of the models. Overall, alanine transaminase, total bilirubin, carcinoembryonic antigen, carbohydrate antigen 19-9 and carbohydrate antigen 72-4 affected the outcome greater than other parameters.

CONCLUSION

ML could be a simple and effective method in non-invasively predicting PNET grades by using the routine data obtained from the results of biochemical and tumor markers.

Pancreatic neuroendocrine tumor: prediction of the tumor grade using magnetic resonance imaging findings and texture analysis with 3-T magnetic resonance

Purpose

The purpose of this study was to evaluate the performance of magnetic resonance imaging (MRI) findings and texture parameters for prediction of the histopathologic grade of pancreatic neuroendocrine tumors (PNETs) with 3-T magnetic resonance.

Patients and methods

PNETs are classified into Grade 1 (G1), Grade 2 (G2), and Grade 3 (G3) tumors based on the Ki-67 proliferation index and the mitotic activity. A total of 77 patients with pathologically confirmed PNETs met the inclusion criteria. Texture analysis (TA) was applied to T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI) maps. Patient demographics, MRI findings, and texture parameters were compared among three different histopathologic subtypes by using Fisher’s exact tests or Kruskal–Wallis test. Then, logistic regression analysis was adopted to predict tumor grades. ROC curves and AUCs were calculated to assess the diagnostic performance of MRI findings and texture parameters in prediction of tumor grades.

Results

There were 31 G1, 29 G2, and 17 G3 patients. Compared with G1, G2/G3 tumors showed higher frequencies of an ill-defined margin, a predominantly solid tumor type, local invasion or metastases, hypo-enhancement at the arterial phase, and restriction diffusion. Four T2-based (inverse difference moment, energy, correlation, and differenceEntropy) and five DWI-based (correlation, contrast, inverse difference moment, maxintensity, and entropy) TA parameters exhibited statistical significance among PNETs (P<0.001). The AUCs of six predicting models on T2WI and DWI ranged from 0.703–0.989.

Conclusion

Our data indicate that MRI findings, including tumor margin, texture, local invasion or metastases, tumor enhancement, and diffusion restriction, as well as texture parameters can aid the prediction of PNETs grading.

Differentiation of hypovascular pancreatic neuroendocrine tumors from pancreatic ductal adenocarcinoma using contrast-enhanced computed tomography

Hypovascular pancreatic neuroendocrine tumors (hypo-PNETs) are often misdiagnosed as pancreatic ductal adenocarcinoma (PDAC). However, the treatment options and prognosis of PNETs and PDAC are substantially different. This retrospective study differentiated hypo-PNETs from PDAC using contrast-enhanced CT (CE-CT). Clinical data and CE-CT findings, including tumor location, size, boundary, pancreatic duct dilatation, local invasion or metastases, tumor contrast enhancement, and tumor-to-pancreas enhancement ratio, were compared between 39 PDACs and 18 hypo-PNETs. At CT imaging, hypo-PNETs showed a higher frequency of a well-defined margin and lower frequencies of pancreatic duct dilatation and local invasion or metastasis when compared with PDAC (p < 0.05 for all). The mean attenuation of hypo-PNETs at the arterial and portal venous phase was significantly higher than that of PDAC (p < 0.001, p = 0.003, respectively). Similar results were observed in tumor-to-pancreas enhancement ratio. Tumor attenuation and tumor-to-pancreas enhancement ratio at the arterial phase showed the largest area under the curve (AUC) of 0.888 and 0.812 with 83.3–88.9% of sensitivity and 61.6–77.0% of specificity. Pancreatic duct dilatation, local invasion or metastasis, and tumor attenuation at the portal venous phase also showed acceptable AUC (0.703–0.748). Thus CE-CT features, especially the enhancement degree at the arterial phases, may be useful for differentiating hypo-PNETs from PDAC using CE-CT.

EUS-guided radiofrequency ablation as an alternative to surgery for pancreatic neuroendocrine neoplasms: Who should we treat?

Pancreatic neuroendocrine neoplasms (PanNENs) are rare tumors, but their incidental diagnosis has significantly increased due to the widespread use of imaging studies. Therefore, most PanNENs are now diagnosed when completely asymptomatic and in early stages. PanNENs are classified according to their grade (Ki-67 index) and can be functional (F-) or nonfunctional (NF-) depending on the presence or absence of a clinical, hormonal hypersecretion syndrome. The mainstay treatment of PanNENs is a surgery that is mostly curative but also associated with significant short- and long-term adverse events. Therefore, less invasive alternative locoregional treatment modalities are warranted. Recently, few case reports and two case series have described EUS-guided radiofrequency ablation (EUS-RFA) for the treatment of patients with both F-PanNENs and NF-PanNENs. If for F-PanNENs EUS-RFA can very easily become the standard of care, for NF-PanNENEs it is still controversial how to select patients for EUS-RFA. A balance between overtreatment (i.e., RFA/surgery in patients who will not progress) and undertreatment (locoregional treatments in patients with undetected metastases) needs to be found based on solid data. The decision should also take into account patients’ comorbidity and risk of postoperative death, life expectancy, tumor location, risk of postoperative fistula and postoperative morbidity, and risk of long-term exocrine and/or endocrine insufficiency. To answer the important question on which a patient should be treated with EUS-RFA, properly designed studies to evaluate the efficacy of this treatment in large cohorts of patients with NF-PanNENs and to establish prognostic factors associated with treatment response are urgently needed.

Resection of Liver Metastases: A Treatment Provides a Long-Term Survival Benefit for Patients with Advanced Pancreatic Neuroendocrine Tumors: A Systematic Review and Meta-Analysis

Purpose

Nonsurgical therapies, including biotherapy, chemotherapy, and liver-directed therapy, provided a limit survival benefit for PNET patients with hepatic metastases. With the development of liver resection technique, there was a controversy on whether to perform a liver resection for these patients.

Methods

A computerized search was made of the Medline/PubMed, EMbase, Cochrane Library, and SinoMed (CBM) before March 2018. A meta-analysis was performed to investigate the differences in the efficacy of liver resection and nonliver resection treatments based on the evaluation of morbidity, 30-day mortality, symptom relief rate, and 1-, 3-, and 5-year survival. Two investigators reviewed all included articles and extracted the data of them. The meta-analysis was performed via Review Manager 5.3 software.

Results

A total of 13 cohort studies with 1524 patients were included in this meta-analysis. Compared with the nonliver resection group, liver resection group had a longer 1-, 3-, and 5-year survival time and a higher symptom relief with an acceptable mortality and morbidity.

Conclusions

Liver resection is a safe treatment and could significantly prolong the long-term prognosis for highly selected patients with resectable liver metastases from PNET. Further randomized, controlled trials are needed.

Imaging presentation of pancreatic neuroendocrine neoplasms

Abstract

Pancreatic neuroendocrine neoplasms (P-NENs) are the second most common solid pancreatic neoplasms. P-NENs have a wide range of imaging features presentations and they can be detected with typical and atypical imaging presentations. Typical and atypical appearances can be explained by pathologic correlations. P-NENs are generally hypervascular lesions, showing a typical enhancement behavior after contrast media injection during imaging methods, but they could also have different imaging features, creating some difficulty in differential diagnosis. For this reason, radiologists should be aware of different imaging presentations of these neoplasms. Radiological evaluation has a critical role in P-NENs identification, characterization, and staging of these neoplasms, especially in those cases in which surgery is the treatment of choice. The present paper shows, indicating the underlying pathologic correlations, typical and atypical presentations of NENs.

Key Points

• P-NENs have a wide range of imaging features presentations, typical and atypical.

• Pathology could help in better understanding the typical P-NENs appearance at imaging.

• P-NENs are generally hypervascular lesions.

• Radiological evaluation has a critical role in P-NENs identification and management.

• Radiologists should know every type of different imaging presentation of P-NENs to better diagnose these kinds of lesions.

Calcified peripancreatic lymph nodes in pancreatic and hepatic tuberculosis mimicking pancreatic malignancy: A case report and review of literature

RATIONALE

Tuberculosis remains a serious menace to the health of people. Isolated hepatic tuberculosis is rare and pancreatic tuberculosis is extremely rare. The preoperative diagnosis of pancreatic tuberculosis remains a great challenge.

PATIENT CONCERNS

A 58-year-old Asian woman was referred to our hospital for evaluation of low back pain for 4 years and abdominal pain for 1 month.

DIAGNOSES

Computed tomography (CT) of the abdomen showed a hypodense mass in the pancreatic head and neck with abundant calcifications, a hypodense lesion in the liver without calcification, peripancreatic lymphadenopathy, calcifications in some lymph nodes. CT-guided fine needle aspiration biopsy of the hepatic lesion was carried out and the cytological examination revealed hepatic tuberculosis.

INTERVENTIONS

The patient was treated with antituberculous therapy for 1 year.

OUTCOMES

Low back pain and abdominal pain disappeared 3 months after initial treatment and after 2 year of follow-up, the patient was asymptomatic.

LESSONS

Our data hint that calcifications in both pancreatic lesions and peripancreatic lymph nodes may suggest pancreatic tuberculosis rather than pancreatic malignancy.

Pancreatic neuroendocrine tumor: prediction of the tumor grade using CT findings and computerized texture analysis

Background Pancreatic neuroendocrine tumors (PNET) include heterogeneous tumors with a variable degree of inherent biologic aggressiveness represented by the histopathologic grade. Although several studies investigated the computed tomography (CT) characteristics which can predict the histopathologic grade of PNET, accurate prediction of the PNET grade by CT examination alone is still limited. Purpose To investigate the important CT findings and CT texture variables for prediction of grade of PNET. Material and Methods Sixty-six patients with pathologically confirmed PNETs (grade 1 = 45, grades 2/3 = 21) underwent preoperative contrast-enhanced CT. Two reviewers determined the presence of predefined CT findings. CT texture was also analyzed on arterial and portal phase using both two-dimensional (2D) and three-dimensional (3D) analysis. Multivariate logistic regression analysis was performed in order to identify significant predictors for tumor grade. Results Among CT findings and CT texture variables, the significant predictors for grade 2/3 tumors were an ill-defined margin (odds ratio [OR] = 7.273), lower sphericity (OR = 0.409) on arterial 2D analysis, higher skewness (OR = 1.972) and lower sphericity (OR = 0.408) on arterial 3D analysis, lower kurtosis (OR = 0.436) and lower sphericity (OR = 0.420) on portal 2D analysis, and a larger surface area (OR = 2.007) and lower sphericity (OR = 0.503) on portal 3D analysis ( P < 0.05). Diagnostic performance of texture analysis was superior to CT findings (AUC = 0.774 vs. 0.683). Conclusion CT is useful for predicting grade 2/3 PNET using not only the imaging findings including an ill-defined margin, but also the CT texture variables such as lower sphericity, higher skewness, and lower kurtosis.

Predictive Effect of the Total Number of Examined Lymph Nodes on N Staging and Survival in Pancreatic Neuroendocrine Neoplasms

OBJECTIVES

We aim to examine the predictive effect of the total number of examined lymph nodes on N stage and survival in pancreatic neuroendocrine neoplasms (pNENs) and to determine the optimal threshold.

METHODS

A pNENs data set from 2004 to 2013 was extracted from the Surveillance, Epidemiology, and End Result database. Multivariate logistic regression and Cox proportional hazards model were used to identify predictive factors associated with N stage and survival, respectively.

RESULTS

Totally, 1280 pNENs were analyzed. The 11 to 15 lymph nodes examined showed a strong association with the N1 stage (6-10 vs 11-15: odds ratio, 0.672; P = 0.042; 11-15 vs 16-20: odds ratio, 1.049; P = 0.840). However, it failed to show any survival benefit in pNENs with or without lymph node metastasis.

CONCLUSIONS

Examining at least 11 lymph nodes may be useful to accurately classify the N stage for pNENs.

Intrinsic Contact Between T and N Classifications in Resected Well-Moderately Differentiated Locoregional Pancreatic Neuroendocrine Neoplasms

BACKGROUND

The role of N classification is controversial in several prognostication systems proposed for pancreatic neuroendocrine neoplasms (pNENs). The widely accepted modified European Neuroendocrine Tumor Society (mENETS) system suggests this contradiction may be related to T classification.

METHODS

Data were collected retrospectively from 981 patients in the Surveillance, Epidemiology, and End Results (SEER) database (1973-2012; cohort 1) and 140 patients from the Pancreatic Cancer Institute of Fudan University (2006-2016; cohort 2). All patients had resected well- to moderately differentiated locoregional pNENs, whereby the mENETS system was adopted. Factors related to N1 classification and the association between N and T classifications were analyzed, and N classification prognosis based on T classification was assessed.

RESULTS

In cohorts 1 and 2, tumor size (2-4 cm: p < 0.001 and p = 0.037, respectively; > 4 cm: p < 0.001 and p = 0.012, respectively) and tumors extending beyond the pancreas (p < 0.001 and p = 0.016, respectively), which are factors for T classification, affected N1 classification. For tumors limited to the pancreas, the N1 classification was associated with tumor size (p < 0.001 and p = 0.046, respectively) and predicted poor disease-specific survival (DSS), while for tumors extending beyond the pancreas, the N1 classification did not affect patient outcomes. Findings obtained with data from the SEER database were reproducible with our institutional data.

CONCLUSIONS

N classification is associated with T classification, limiting the value of N1 classification for the pNENs tumor-node-metastasis system. A new risk model is necessary to predict patient outcomes and guide clinical practice for the prognosis of pNENs.

Calcified pancreatic and peripancreatic neoplasms: spectrum of pathologies

A variety of pancreatic and peripancreatic neoplasms may contain calcifications. We present a review of common to uncommon pancreatic neoplasms that may contain calcifications to include ductal adenocarcinoma, pancreatic neuroendocrine tumors, serous cystadenomas, solid pseudopapillary tumors, intraductal papillary mucinous neoplasms, mucinous cystic neoplasms, and lymphoepithelial cysts. In addition, duodenal mucinous adenocarcinoma can present as a peripancreatic mass that may contain calcification. Knowledge of the spectrum of calcification patterns can help the interpreting radiologist provide a meaningful differential.

Imaging of secretory tumors of the gastrointestinal tract

Gastrointestinal secretory tumors, or gastroenteropancreatic neuroendocrine tumors, encompass a wide array of endocrine cell tumors. The significance of these tumors lies in their ability to alter physiology through hormone production as we well as in their malignant potential. Functioning tumors may present earlier due to symptomatology; conversely, non-functioning tumors are often diagnosed late as they reach large sizes, causing symptoms secondary to local mass effect. Imaging aids in the diagnosis, staging, and prognosis and provides key information for presurgical planning. Although most of these tumors are sporadic, some are associated with important syndromes and associations, knowledge of which is critical for patient management. In this article, we provide an overview of secretory and neuroendocrine tumors of the GI tract and pancreas.

Vascularity and Tumor Size are Significant Predictors for Recurrence after Resection of a Pancreatic Neuroendocrine Tumor

BACKGROUND

It is difficult to identify patients at high risk of recurrence after pancreatectomy for pancreatic neuroendocrine tumor (PNET) using only the grading classification, especially the G2 category, which includes both benign and low- and high-grade malignant tumors.

METHODS

Forty-one patients with PNET who underwent pancreatectomy were enrolled in this study. We defined the computed tomography (CT) ratio as the CT value of the tumor divided by that of non-tumorous pancreatic parenchyma using the late arterial phase dynamic CT. The optimal cut-off values for CT ratio and tumor size were determined using p-values that were calculated using the log-rank test.

RESULTS

The optimal cut-off values of CT ratio and tumor size for dividing patients into groups according to the greatest difference in disease-free survival (DFS) were 0.85 (p < 0.001) and 3.0 cm (p < 0.001), respectively. In analysis using Spearman's correlation coefficient, CT ratio (p = 0.007) and tumor size (p = 0.003) were individually associated with the Ki-67 proliferative index. Cox proportional hazard analysis identified that a CT ratio <0.85 (n = 10, p = 0.006) and tumor size ≥3.0 cm (n = 13, p = 0.023) were independent prognostic factors associated with DFS. All patients in the CT ratio ≥0.85 and tumor size <3.0 cm group (n = 23, including seven patients with G2 disease) did not develop recurrence after surgery. On the other hand, 5-year DFS in the CT ratio <0.85 and tumor size ≥3.0 cm group (n = 5, including three patients with G2 disease) was zero.

CONCLUSIONS

PNETs with a CT ratio <0.85 and tumor size ≥3.0 cm should be considered as having a high risk of recurrence after pancreatectomy.

Imaging Patterns of Intratumoral Calcification in the Abdominopelvic Cavity

Intratumoral calcification is one of the most noticeable of radiologic findings. It facilitates detection and provides information important for correctly diagnosing tumors. In the abdominopelvic cavity, a wide variety of tumors have calcifications with various imaging features, though the majority of such calcifications are dystrophic in nature. In this article, we classify the imaging patterns of intratumoral calcification according to number, location, and morphology. Then, we describe commonly-encountered abdominopelvic tumors containing typical calcification patterns, focusing on their differentiable characteristics using the imaging patterns of intratumoral calcification.

Contrast-enhanced MDCT in patients with pancreatic neuroendocrine tumours: correlation with histological findings and diagnostic performance in differentiation between tumour grades

AIM

To identify the multidetector computed tomography (MDCT) features of pancreatic neuroendocrine tumours (pNETs), which correlate with tumour histology and enable preoperative grading.

MATERIALS AND METHODS

Thirty-nine patients with histologically confirmed pNET who underwent preoperative contrast-enhanced MDCT were included in this study. Nineteen tumours were classified as Grade 1 (G1) and 20 as Grade 2 (G2). Histopathology slides were reviewed to assess the intratumoural microvascular density (MVD) and the amount of tumour stroma. Computed tomography (CT) image analysis included tumour size, margin delineation, calcifications, homogeneity, contrast enhancement (CE) pattern, tumour absolute and relative enhancement, presence of cystic changes, pancreatic duct dilatation, regional and distant metastases. The diagnostic ability to predict tumour grade was measured for each MDCT finding and their combinations.

RESULTS

The mean arterial enhancement ratio had a mean±standard deviation of 1.53±0.45 in G1 and 1.01±0.33 in G2 pNETs (p=0.0003) and correlated with intratumoural microvascular density (MVD; r=0.55, p=0.0002). Tissue stroma percentage did not correlate with imaging findings. Late CE of the tumour (the peak attenuation observed in the venous phase) was significantly associated with G2. Tumour size >20 mm, arterial enhancement ratio <1.1, and late CE showed 74.4%, 79.5%, and 74.4% accuracy, respectively, in diagnosing G2 tumours, while the accuracy of at least two of these criteria used in combination was 82%. Based on these results, a diagnostic algorithm was proposed, which showed high interobserver agreement (k=0.82) in the prediction of tumour grade.

CONCLUSION

Contrast-enhanced MDCT features correlate with histological findings and enable the differentiation between G1 and G2 pNETs during preoperative examination.

Indications for Surgical Resection in Low-Grade Pancreatic Neuroendocrine Tumors

The role of surgical resection in low-grade pancreatic neuroendocrine tumors (P-NET) is unclear. The patients diagnosed with low-grade P-NET from 1988 to 2012 were identified in SEER. Five hundred and sixty-one patients met the inclusion criteria. A majority were white (82.9%), and node negative (69.9%). Univariate analysis revealed that tumor size (<2 cm 8.3%, 2–4 cm 38.5%, and >4 cm 40.3%; P < 0.0001) and surgery (30.9% vs 25.3%; P = 0.0014) were associated with the risk of lymph node metastases (LNM). In contrast, age ( P = 0.8360), gender ( P = 0.4903), and race ( P = 0.4235) were not. Five-year disease-free survival was associated with size (<2 cm 89.4%, 2–4 cm 80.0%, and >4 cm 74.5%; P = 0.0089), LNM (72.4% vs 82.9%; P = 0.0025), and surgery (84.3% vs 47.5%; P < 0.0001). Cox regression model showed that the association with LNM ( P = 0.0025) and surgery ( P < 0.0001) was significant. Surgery was associated with an improved disease-free survival for tumors >2 cm (2–4 cm, 84.4% vs 26.0% at five years; P = 0.0003, and >4 cm, 80.5% vs 49.5% at five years; P < 0.0001) but not for those with tumor size <2 cm ( P = 0.4525). In conclusions, low-grade P-NETs in patients with tumor size >2 cm showed an increased risk of LNM and improved survival with resection.

Uncommon presentations of common pancreatic neoplasms: a pictorial essay

Pancreatic neoplasms are a wide group of solid and cystic lesions with different and often characteristic imaging features, clinical presentations, and management. Among solid tumors, ductal adenocarcinoma is the most common: it arises from exocrine pancreas, comprises about 90% of all pancreatic neoplasms, and generally has a bad prognosis; its therapeutic management must be multidisciplinary, involving surgeons, oncologists, gastroenterologists, radiologists, and radiotherapists. The second most common solid pancreatic neoplasms are neuroendocrine tumors: they can be divided into functioning or non-functioning and present different degrees of malignancy. Cystic pancreatic neoplasms comprise serous neoplasms, which are almost always benign, mucinous cystic neoplasms and intraductal papillary mucinous neoplasms, which can vary from benign to frankly malignant lesions, and solid pseudopapillary tumors. Other pancreatic neoplasms, such as lymphoma, metastases, or pancreatoblastoma, are rarely seen in clinical practice and have different and sometimes controversial managements. Rare clinical presentations and imaging appearance of the most common pancreatic neoplasms, both solid and cystic, are more frequently seen and clinically relevant than rare pancreatic tumors; their pathologic and radiologic appearances must be known to improve their management. The purpose of this paper is to present some rare or uncommon clinical and radiological presentations of common pancreatic neoplasms providing examples of multi-modality imaging approach with pathologic correlations, thus describing the histopathological bases that can explain the peculiar imaging features, in order to avoid relevant misdiagnosis and to improve lesion management.

Postoperative Complications, In-Hospital Mortality and 5-Year Survival After Surgical Resection for Patients with a Pancreatic Neuroendocrine Tumor: A Systematic Review

Studies on postoperative complications and survival in patients with pancreatic neuroendocrine tumors (pNET) are sparse and randomized controlled trials are not available. We reviewed all studies on postoperative complications and survival after resection of pNET. A systematic search was performed in the Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE from 2000-2013. Inclusion criteria were studies of resected pNET, which described postoperative complications separately for each surgical procedure and/or 5-year survival after resection. Prospective and retrospective studies were pooled separately and overall pooled if heterogeneity was below 75%. The random-effect model was used. Overall, 2643 studies were identified and after full-text analysis 62 studies were included. Pancreatic fistula (PF) rate of the prospective studies after tumor enucleation was 45%; PF-rates after distal pancreatectomy, pancreatoduodenectomy, or central pancreatectomy were, respectively, 14-14-58%. Delayed gastric emptying rates were, respectively, 5-5-18-16%. Postoperative hemorrhage rates were, respectively, 6-1-7-4%. In-hospital mortality rates were, respectively, 3-4-6-4%. The 5-year overall survival (OS) and disease-specific survival (DSS) of resected pNET without synchronous resected liver metastases were, respectively, 85-93%. Heterogeneity between included studies on 5-year OS in patients with synchronous resected liver metastases was too high to pool all studies. The 5-year DSS in patients with liver metastases was 80%. Morbidity after pancreatic resection for pNET was mainly caused by PF. Liver resection in patients with liver metastases seems to have a positive effect on DSS. To reduce heterogeneity, ISGPS criteria and uniform patient groups should be used in the analysis of postoperative outcome and survival.