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Everything you need to know about Computed Tomography (CT) & CT Scanning

Pancreas: Neuroendocrine Tumors (pnet) Imaging Pearls - Educational Tools | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
Imaging Pearls ❯ Pancreas ❯ Neuroendocrine Tumors (PNET)

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  • ”The octreoscan is 70%-95% sensitive for detecting PNETs with somatostatin receptors. However, not all PNETs have somatostatin receptors; therefore, a negative octreotide scan does not rule out PNETs. In addition, lymphocytes can also display somatostatin receptors on their surface and cause uptake of the radiolabeled analog creating a false positive. One of the two IPAS patients in our series had a false positive octreotide scan; this displays the challenges that persist in diagnosing incidental pancreatic lesions.”
    Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
    Baugh KA et al.
    J Surg Res. 2019 Apr;236:144-152
  • “Diagnosis of incidental distal pancreatic solid lesions like IPAS creates significant difficulty for pancreas surgeons. Our algorithm provides needed structure to the work up. Although this is designed to rule out IPAS, this algorithm can be used as a starting point for the work up of any incidentally found pancreatic mass. In the past, the work up of incidentally found lesions led to the development of useful guidelines in the adrenal gland. Therefore, establishment of protocols like the one proposed for pancreatic lesions may aid in the development of future guidelines for the pancreas.”
    Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
    Baugh KA et al.
    J Surg Res. 2019 Apr;236:144-152
  • “Work up of an incidental pancreatic solid lesion remains a challenge, especially for the diagnosis of IPAS. Successful diagnosis will require a strong index of suspicion, a multi- disciplinary approach, and the use of the proposed algorithm. In time, this may aid clinicians in the distinction between benign IPAS, which requires no further action and a lesion requiring resection.”
    Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
    Baugh KA et al.
    J Surg Res. 2019 Apr;236:144-152
  • Purpose: To assess qualitative and quantitative imaging features on enhanced CT that may differentiate pancreatic neuroendocrine tumors (PNETs) from pancreatic renal cell carcinoma (RCC) metastases.
    Conclusions: Compared to pancreatic RCC metastases, PNETs are larger, more frequently solitary, contain calcification, show MPD dilation, and are subjectively and quantitatively more heterogeneous tumors.
    Differentiation of pancreatic neuroendocrine tumors from pancreas renal cell carcinoma metastases on CT using qualitative and quantitative features
    van der Pol CB et al.
    Abdominal Radiology 2019 (in press)
  • “PNETs were larger than RCC metastases (37 ± 23 mm vs. 26 ± 21 mm, P = 0.038), more frequently solitary (P < 0.001), subjectively more heterogeneous (P = 0.033/0.144, R1/R2), and associated with calcification (P = 0.002/0.004) and MPD dilation (P = 0.025/0.006). Agreement for subjective features was moderate-to-almost perfect (K = 0.4879–0.9481). Quantitative texture analysis showed higher entropy in PNETs (6.32 ± 0.49 versus 5.96 ± 0.53; P = 0.004) with no difference in other features studied (P > 0.05). Entropy had ROC area under the curve for diagnosis of PNET of 0.77 ± 0.06, with optimal sensitivity/specificity of 71.4/79.1%.”
    Differentiation of pancreatic neuroendocrine tumors from pancreas renal cell carcinoma metastases on CT using qualitative and quantitative features
    van der Pol CB et al.
    Abdominal Radiology 2019 (in press)
  • “Renal cell carcinoma (RCC) is among the most common primary malignancies that metastasize to the pancreas and typically appears as a hypervascular pancreatic mass on CT or MRI [. RCC metastases can resemble primary pancreatic neuroendocrine tumors (PNETs), which are also commonly hypervascular masses.”
    Differentiation of pancreatic neuroendocrine tumors from pancreas renal cell carcinoma metastases on CT using qualitative and quantitative features
    van der Pol CB et al.
    Abdominal Radiology 2019 (in press)
  • “First-order texture features were extracted by histogram analysis, specifically; Kurtosis (a measure of histogram flatness), Skewness (a measure of histogram asymmetry), and Entropy (a measure of histogram irregularity) as described previously. Manual contouring of tumors was independently repeated in 17% of patients (10/60) for 17 tumors by a second fellowship-trained abdominal radiologist (NS), to assess reproducibility of segmentation.”
    Differentiation of pancreatic neuroendocrine tumors from pancreas renal cell carcinoma metastases on CT using qualitative and quantitative features
    van der Pol CB et al.
    Abdominal Radiology 2019 (in press)
  • “With respect to texture analysis features studied, entropy was significantly higher in PNETs compared to RCC metastases (6.32 ± 0.49 vs. 5.96 ± 0.53, P = 0.004) with a trend towards higher levels of kurtosis and skewness, although the difference in the latter two features did not reach statistical significance between groups (P = 0.067 and 0.099, respectively).”
    Differentiation of pancreatic neuroendocrine tumors from pancreas renal cell carcinoma metastases on CT using qualitative and quantitative features
    van der Pol CB et al.
    Abdominal Radiology 2019 (in press)
  • “The presence of tumor calcification and main pancreatic duct dilation were specific features for PNETs, whereas pancreatic RCC metastases tended to be smaller and were more frequently multiple. PNETs appeared subjectively and quantitatively more heterogeneous using texture analysis. Our results suggest that enhanced CT imaging features may accurately differentiate between PNET and pancreatic RCC metastases which may potentially obviate the need for histological sampling in select cases.”
    Differentiation of pancreatic neuroendocrine tumors from pancreas renal cell carcinoma metastases on CT using qualitative and quantitative features
    van der Pol CB et al.
    Abdominal Radiology 2019 (in press)

  • Differentiation of pancreatic neuroendocrine tumors from pancreas renal cell carcinoma metastases on CT using qualitative and quantitative features
    van der Pol CB et al.
    Abdominal Radiology 2019 (in press)
  • “PNETs often appear as solid hypervascular neoplasms on arterial or occasionally portal venous phase imaging. Prior work suggests that approximately 22% of PNETs contain calcification, similar to our study. Although MPD dilation is more commonly seen secondary to pancreatic adenocarcinoma rather than PNETs, a minority of PNETs have been found to cause MPD dilation, which may be due to mass effect from the tumor itself or from fibrotic stricture formation secondary to serotonin or related metabolites released by the tumor. In our study, we found that up to one-quarter of PNETs had associated MPD dilation, whereas this finding was not present for any pancreatic RCC metastases.”
    Differentiation of pancreatic neuroendocrine tumors from pancreas renal cell carcinoma metastases on CT using qualitative and quantitative features
    van der Pol CB et al.
    Abdominal Radiology2019 (in press)
  • In conclusion, our study demonstrates that subjective imaging features and quantitative texture analysis may differentiate PNET from pancreatic RCC metastases. Tumor calcification, solitary masses, and MPD dilation were specific features for PNET but lacked sensitivity, whereas the quantitative texture analysis feature entropy improved sensitivity for diagnosis with moderate overall accuracy.”
    Differentiation of pancreatic neuroendocrine tumors from pancreas renal cell carcinoma metastases on CT using qualitative and quantitative features
    van der Pol CB et al.
    Abdominal Radiology2019 (in press)
  • Our results suggest that imaging features at enhanced CT may accurately differentiate between pancreatic RCC metastases and PNET and could potentially obviate the need for his- tological confirmation, especially to confirm the presence of metastatic disease in patients with a history of RCC, although will require confirmation in larger sample sizes.
    Differentiation of pancreatic neuroendocrine tumors from pancreas renal cell carcinoma metastases on CT using qualitative and quantitative features
    van der Pol CB et al.
    Abdominal Radiology2019 (in press)
  • “Pancreatic NETs originate from the islet cells of Langerhans and are divided into low-, intermediate-, and high-grade according to the World Health Organization classification. High-grade NETs more frequently show vascular invasion, lymph node metastasis, and diffusion restriction compared with low-grade; therefore, high- grade NETs can mimic PDAC on images. However, high-grade NETs usually do not show pancreatic duct dilatation. In addition, they occasionally accompany tumor thrombus, which can be helpful in the differential diagnosis of high-grade NETs from PDAC. Liver metastases from NETs frequently reveal findings of hypervascularity and intralesional hemorrhage, in contrast to those from PDAC, which reveal hypovascularity.”
    Pancreas Ductal Adenocarcinoma and its Mimics: Review of Cross- sectional Imaging Findings for Differential Diagnosis.
    Kim, SS, et al.
    Journal of the Belgian Society of Radiology. 2018; 102(1): 71, 1–8.
  • “SPTs are uncommon neoplasms with low malignancy potential, occurring predominantly in young women. Calcification, cystic change, and internal hemorrhage due to weak vascular channels are characteristic features of SPT. However, small (≤3 cm) SPTs show different imaging findings from larger ones, primarily a homogeneous nature. Small SPTs show a pure solid consistency, well-defined margin, and diffusion restriction on magnetic resonance (MR) imaging. After contrast infusion, small SPTs reveal an early heterogenous nature, followed by a progressive enhancement pattern.”
    Pancreas Ductal Adenocarcinoma and its Mimics: Review of Cross- sectional Imaging Findings for Differential Diagnosis.
    Kim, SS, et al.
    Journal of the Belgian Society of Radiology. 2018; 102(1): 71, 1–8.
  • VIPomas are rare tumors with an incidence of 0.05% to 2.0% and can occur both in children and adults. In adults, they occur most commonly between the ages of 30 to 50 years and are mostly intra-pancreatic (95%). A small proportion of tumors secreting VIP have been reported as colorectal cancer, lung cancer, pheochromocytoma, neurofibroma, and ganglioneuroblastoma. Majority of VIPomas occur as isolated tumors, but in about 5% of patients, they are part of the multiple endocrine neoplasia type 1 (MEN1) syndromes. More than 50% of VIPomas have metastasized by the time of diagnosis.
  • Excessive secretion of VIP from the tumor has multiple effects on different organ systems, with its primary effects being on the GI system. VIP is a neurotransmitter belonging to the secretin- glucagon family and consists of 28 amino acids. It is a potent stimulator of intestinal cyclic adenosine monophosphate (cAMP) production and inhibitor of gastric acid secretion. It promotes vasodilation, glycogenolysis, lipolysis, and bone resorption. Effects secondary to these actions of VIP include huge secretion of water and electrolytes from the GI epithelial cells, hypokalemia, facial flushing, decreased gastric acidity, elevated blood glucose, and hypercalcemia.
  • Diagnosis of VIPoma is made in patients with secretory diarrhea usually greater than 3.0 liters per day with a serum VIP level around 250 to 500 pg/ml (reference range is less than 190 pg/ml). Secretory diarrhea has a low fecal osmotic gap of less than 50 mOsm/kg. It is important to repeat levels of VIP to confirm diagnosis since levels may not be elevated between episodes of watery diarrhea. It is also imperative to determine VIP levels when the patient is symptomatic, as the VIPoma may only secrete VIP intermittently. Hence, a normal level may be a false negative. Among children suspected with VIPoma, catecholamine levels should also need to be measured. Levels of pancreatic polypeptide are elevated in tumors originating from the pancreas.
  • “Multidetector computed tomography now offers a powerful tool for the evaluation, diagnosis, and risk stratification of pancreatic cystic neoplasms. Improvements in image quality and spatial reso- lution, as well as sophisticated 3-D reconstruction techniques, allow exquisite assessment of the internal architecture of these lesions that not only may allow the radiologist to provide a specific diagnosis but also to assess features that might predict the risk of malignancy.”

    
Multidetector Computed Tomography in the Evaluation
of Cystic Tumors of the Pancreas 
Siva P. Raman, Elliot K. Fishman 
(in) Cystic Tumors of the Pancreas: Diagnosis and Treatment 
Marco Del Chiaro, StephanL.Haas, RichardD.Schulick Editors
© Springer International Publishing Switzerland 2016
  • “Cystic neuroendocrine tumors almost always demonstrate the presence of either a peripheral “rind” of hypervascular enhancing solid tissue or, alternatively, hyperenhancing mural nodularity along the margins of the cyst. This diagnosis is one of the primary reasons for the inclusion of arterial phase images in the evaluation of a suspected pancreatic cystic neoplasm, as both the solid rim and mural nodularity associated with these lesions are almost always most conspicuous on the arterial phase and may be more difficult to appreciate on venous phase imaging.”

    
Multidetector Computed Tomography in the Evaluation
of Cystic Tumors of the Pancreas 
Siva P. Raman, Elliot K. Fishman 
(in) Cystic Tumors of the Pancreas: Diagnosis and Treatment 
Marco Del Chiaro, StephanL.Haas, RichardD.Schulick Editors
© Springer International Publishing Switzerland 2016
  • “Unfortunately, given that the hypervascular components may be less conspicuous on the venous phase, these lesions are not infre- quently incorrectly diagnosed as IPMN when only a venous phase is acquired. In addition, the presence of other signs of metastatic dis- semination can also be a strong clue to the correct diagnosis, including hyperenhancing liver or lymph node metastases.”


    Multidetector Computed Tomography in the Evaluation
of Cystic Tumors of the Pancreas 
Siva P. Raman, Elliot K. Fishman 
(in) Cystic Tumors of the Pancreas: Diagnosis and Treatment 
Marco Del Chiaro, StephanL.Haas, RichardD.Schulick Editors
© Springer International Publishing Switzerland 2016
  • “Thirty-three patients suspected of having a functioning tumor of the pancreas were studied with computed tomography (CT); 25 had angiographic studies also. Thirty-one cases were confirmed surgically; the other two were lost at follow-up and were excluded from the series. Of the 31 patients, 21 had insulinomas, five had Zollinger-Ellison syndrome, and five had assorted apudomas. CT was positive in 71% of the cases and negative in 29%; 22.6% of the studies were false negative and 6.4% were true negative. There were no false positives. Of the 21 patients with insulinomas, only one had false-negative CT and angiographic studies, caused by diffuse microadenomatosis. In one patient, two separate lesions of the pancreas were seen and identified correctly on both CT and angiography. All identified lesions smaller than 2 cm were seen only because of a hyperdensity on the enhanced CT scan. Lesions larger than 2 cm were identified either because their size distorted the pancreatic contour or because of their vascularity. The importance of proper CT technique using fast scanners and repeated bolus injections of contrast medium is stressed.”

    CT of functioning tumors of the pancreas. Rossi P et al. AJR Am J Roentgenol. 1985 Jan;144(1):57-60.
  • “Thirty-three patients suspected of having a functioning tumor of the pancreas were studied with computed tomography (CT); 25 had angiographic studies also. Thirty-one cases were confirmed surgically; the other two were lost at follow-up and were excluded from the series. Of the 31 patients, 21 had insulinomas, five had Zollinger-Ellison syndrome, and five had assorted apudomas. CT was positive in 71% of the cases and negative in 29%; 22.6% of the studies were false negative and 6.4% were true negative.”

    CT of functioning tumors of the pancreas. Rossi P et al. AJR Am J Roentgenol. 1985 Jan;144(1):57-60.
  • “Thirty-three patients suspected of having a functioning tumor of the pancreas were studied with computed tomography (CT); 25 had angiographic studies also. Thirty-one cases were confirmed surgically; the other two were lost at follow-up and were excluded from the series. Of the 31 patients, 21 had insulinomas, five had Zollinger-Ellison syndrome, and five had assorted apudomas. CT was positive in 71% of the cases and negative in 29%; 22.6% of the studies were false negative and 6.4% were true negative.”

    CT of functioning tumors of the pancreas. Rossi P et al. AJR Am J Roentgenol. 1985 Jan;144(1):57-60.
  • Pancreatic neuroendocrine tumors (PNETs): Facts
    - 1% to 2% of all pancreatic neoplasms
    - Functioning vs non-functioning tumors
    - Local invasiveness of tumors will vary
    - May be syndrome related (MEN 1)
    - Surgery is usually treatment of choice
  • Pancreatic neuroendocrine tumors (PNETs): Presentation
    - Functioning tumors produce a range of hormones including;
      insulin (hypoglycemia)
      gastrin
      glucagon
      vasoactive intestinal peptide (VIP)
      somatostatin
  • Pancreatic neuroendocrine tumors (PNETs): Detection
    - Computed Tomography (CT)
    - Magnetic Resonance Imaging (MRI)
    - Ultrasound
    - EUS (endoscopic ultrasound)
    - Catheter Angiography
    - Nuclear Medicine Studies
  • Pancreatic neuroendocrine tumors (PNETs): CT
    - Incidental finding as 70% of lesion are non-functioning
    - Frequency of detection of incidental PNET is based on protocol design including phase(s) of acquisition, multiphase acquisition, contrast injection rate and timing
  • Surgical Management: Options
    - All tumors greater than 2 cm should be resected, typically with formal anatomic resection (pancreaticoduodenectomy, distal pancreatectomy) including negative margins and regional lymph nodes.
    - Evidence suggests incidental tumors less than 1 cm can be followed with surveillance.
  • Surgical Management: Options
    - Some studies with short-term follow-up suggest that all nonfunctioning PNET less than 2 cm might be followed with surveillance, with resection for growth.
    - Pancreatic enucleation is most appropriate for small PNETs; lymph node resection should be considered for tumors 1 to 2 cm in size.
  • Surgical Management: Options
    MEN1 is associated with small, multifocal tumors, most of which have a low risk of progression. Surgery is reserved for tumors greater than 1 to 2 cm in size.

    Surgical Management of Pancreatic Neuroendocrine Tumors Thomas E. Clancy Hematology/Oncology Clinics of North America Volume 30, Issue 1, February 2016, Pages 103–118
  • “The World Health Organization classifies neuroendocrine tumors into different grades based on histologic characteristics. Well-differentiated tumors include low-grade (G1) tumors with a low mitotic count and Ki-67 proliferative index of less than 3% as well as intermediate-grade (G2) tumors with mitotic counts of 2 to 20 per high-power field (HPF) and Ki-67 rate of 3% to 20%. Poorly differentiated tumors or high-grade (G3) tumors have mitotic rates more than 2 per 10 HPF and Ki-67 rate of greater than 20%. High-grade tumors, often referred to as neuroendocrine carcinomas, display more aggressive clinical behavior and unlike, well-differentiated tumors, are generally not candidates for surgical resection.”

    Surgical Management of Pancreatic Neuroendocrine Tumors Thomas E. Clancy Hematology/Oncology Clinics of North America Volume 30, Issue 1, February 2016, Pages 103–118
  • “Studies have demonstrated a direct relationship between tumor size and risk of metastases.56 With increased utilization and improved accuracy of cross-sectional imaging, an increasing number of incidental, small (<2.0 cm) PNETs are now identified. Given that only 6% of nonfunctional PNETs less than 2 cm in size will be metastatic at diagnosis, some suggests a conservative strategy; the optimal management of these more indolent neoplasms is debated.”

    Surgical Management of Pancreatic Neuroendocrine Tumors Thomas E. Clancy Hematology/Oncology Clinics of North America Volume 30, Issue 1, February 2016, Pages 103–118
  • Small diameter at diagnosis (<2 cm) is not an assurance of a benign behavior, and no size cut-off exists beyond which malignancy can be excluded safely. As a consequence, most institutions have recommended operative resection for all patients with NF-pNETs. However, pancreatic resections are associated with a risk of postoperative morbidity, mortality, and of long-term complications, even in high-volume centers. In this light, some authors proposed clinical surveillance rather than surgery for selected patients with small, incidentally discovered NF-pNET (i.e., older patients with comorbidities).

    Incidental diagnosis as prognostic factor in different tumor stages of nonfunctioning pancreatic endocrine tumors Crippa S et al. Surgery Vol 155, Issue 1, January 2014, Pages 145–153
  • “The absence of symptoms is not an assurance of benign behavior, even in small tumors. In a previous report we showed that only 6% of incidental NF-pNETs than 2 cm in size had malignancy, but no patient died of disease after a median follow-up of 47 months. A similar malignancy-rate (7.7%) in this subgroup of patients is reported by Haynes et al.”

    Incidental diagnosis as prognostic factor in different tumor stages of nonfunctioning pancreatic endocrine tumors Crippa S et al. Surgery Vol 155, Issue 1, January 2014, Pages 145–153
  • “Somatostatin-receptor scintigraphy 
Similar to MRI, SRS is often used to localize PNETs when traditional cross-sectional imaging fails. SRS uses radiolabeled somatostatin analogues that bind to receptors expressed by the PNET.47 Hence, lesions with few somatostatin receptors, such as insulinomas, are often missed with this technique. The standard method of performing SRS is with injection of 111In-DTPA-octreotide (OctreoScan). SRS is particularly useful in assessing the burden of extrapancreatic metastatic disease, and also should be routinely performed to assess the somatostatin receptor status before treatment with somatostatin analogues. Overall, the sensitivity of SRS to detect gastrinomas, VIPomas, glucagonomas, and nonfunctioning PNETs ranges from 75% to 100%; however, for insulinomas, the sensitivity falls to 50% to 60%.”


    Islet Cell Tumors of the Pancreas 
Sunil Amin, Michelle Kang Kim
Gastroenterol Clin N Am 45 (2016) 83–100
  • “Although 90% of PNETs occur sporadically, these tumors are also well-recognized features of 4 familial syndromes: multiple endocrine neoplasia type I (MEN1), von Hippel-Lindau syndrome (VHL), neurofibromatosis type 1 (NF1), and tuberous scle- rosis complex (TSC).7,8 Each of these syndromes is inherited in an autosomal domi- nant pattern, and the causative genes are MEN1, VHL, NF1, and TSC1/2, respectively.”


    Islet Cell Tumors of the Pancreas 
Sunil Amin, Michelle Kang Kim
Gastroenterol Clin N Am 45 (2016) 83–100
  • “Von Hippel-Lindau Syndrome 
Although pancreatic lesions are common in VHL, only 10% to 17% of patients with VHL develop PNETs. Furthermore, almost all VHL-associated PNETs are nonfunctioning. The mean age of diagnosis of PNETs is 29 to 38 years, and unlike MEN1, most of these lesions are solitary as opposed to multifocal.”

    Islet Cell Tumors of the Pancreas 
Sunil Amin, Michelle Kang Kim
Gastroenterol Clin N Am 45 (2016) 83–100
  • “The clinical presentation of PNETs is frequently divided into 2 broad categories: functioning and nonfunctioning tumors. Functional tumors present with a defined clinical syndrome secondary to hormone hypersecretion. Functional PNETs included insulino- mas, gastrinomas, glucagonomas, VIPomas, and somatostatinomas. Nonfunctional tumors, which compromise 60% to 90% of all PNETs, do not present with symptoms related to hormone hypersecretion, although in some cases circulating hormone levels may be elevated nonetheless.”

    Islet Cell Tumors of the Pancreas 
Sunil Amin, Michelle Kang Kim
Gastroenterol Clin N Am 45 (2016) 83–100
  • “The enhancement characteristics of a PNET on CT may also have prognostic value, as lesions that hypoenhance on CT scan tend to have worse overall survival than lesions that are isoenhancing or hyperenhancing (5-year survival 54% vs 89% vs 93%).”

    Islet Cell Tumors of the Pancreas 
Sunil Amin, Michelle Kang Kim
Gastroenterol Clin N Am 45 (2016) 83–100
  • “MEN1 is characterized by PNETs in association with pituitary and parathyroid tumors. Almost all patients with MEN1 (>95%) will develop a PNET during their lifetime, although most of these will be nonfunctioning “micro-adenomas” (smaller than 0.5 cm) that are typically multifocal. Fewer than 15% of these nonfunctioning tumors will be large enough to be symptomatic.10 Functioning PNETs that are symptom- atic occur in between 20% and 70% of patients with MEN1, with approximately 55% of these patients presenting with Zollinger-Ellison (ZE) syndrome due to an underlying gastrinoma, and 20% presenting with symptoms from an insulinoma.”


    Islet Cell Tumors of the Pancreas 
Sunil Amin, Michelle Kang Kim
Gastroenterol Clin N Am 45 (2016) 83–100
  • “Other functioning PNETs, such as VIPoma, glucagonoma, and somatostatinoma occur in fewer than 3% of patients with MEN1.12 The management of patients with MEN1 with PNETs is of particular significance, as PNETs are the leading cause (40%) of disease-specific mortality among patients with MEN1.13,14 Furthermore, the mean age of death among patients with MEN1 with PNETS is 55 years, which is lower than that of both the gen- eral population and patients with non-MEN1 PNETs.”

    Islet Cell Tumors of the Pancreas 
Sunil Amin, Michelle Kang Kim
Gastroenterol Clin N Am 45 (2016) 83–100
  • “Once a diagnosis of Cystic Pancreatic Neuroendocrine Tumors (CPEN) has been established, the recommended treatment is surgical resection. Although some series suggest that CPENs have a lower Ki67 proliferative index and risk of carcinoma than solid PNETs, CPENs still harbor an 11% to 14% risk of malignancy and 8% to 14% risk of nodal or distant metastases, necessitating surgical resection as the only potential curative treatment.”
Diagnosis and Management of Pancreatic Cystic Neoplasms
        Kim TS, Fernandez-del Castillo C
Hematology/Oncology Clin North America
Volume 29, Issue 4, August 2015, Pages 655–674
  • What if the pancreatic mass is vascular?
    • Vascular Pancreatic Mass: Differential Dx
       • Neuroendocrine tumor (PNET)
       • Metastases to the Pancreas
       • Serous Cystadenoma (vascular border on arterial phase images)
  • Vascular Pancreatic Mass: Differential Dx
    • Neuroendocrine tumor (PNET) are the most classic vascular lesions and range in size from 5mm to 20 cm
    • Metastases to the Pancreas are usually from renal cell carcinoma but occur 10-15 years after the primary tumor has been resected.
    • Pearl: if the patient has an absent kidney think metastatic renal cell carcinoma
  • Vascular Pancreatic Mass: Differential Dx
    • Serous Cystadenoma (vascular border on arterial phase images) are rarely put in the vascular mass category but can have a vascular rim with stretching of the hepatic Artery or SMA. This is uncommon but can be a great mimicker of a PNET.
  • “Incidental detection of pancreatic neuroendocrine tumors (PNETs) has substantially increased over the last decade due to widespread use of advanced imaging studies. Reliable initial imaging-based characterization is crucial for the differential diagnosis from other exocrine neoplasms and to determine the appropriate management plan.”


    Aace/Ace disease state clinical review: pancreatic neuroendocrine incidentalomas.
Herrera MF et al.
Endocr Pract. 2015 May;21(5):546-53
  • “It has been suggested that non-MEN related, nonfunctioning, and asymptomatic PNETs <2 cm with a Ki-67 index ≤2% carry a low risk of metastasis and may be observed in the absence of clinical or radiologic criteria of malignancy or progression, especially in older patients. However, because metastases may occur with long delay with smaller PNETS, physicians should consider patient age, lesion location, and the risks of operation, and patients not undergoing surgery need to be closely followed closely.”


    Aace/Ace disease state clinical review: pancreatic neuroendocrine incidentalomas.
Herrera MF et al.
Endocr Pract. 2015 May;21(5):546-53
  • “The natural history of pancreatic neuroendocrine tumors (panNETs) is extremely variable. One of the most controversial problems in diagnosis is the accurate prediction of the clinical behavior of these tumors. PanNETs that behave aggressively with a malignant course may have bland cytologic features, while some tumors with previously described "malignant" features may behave in a benign or indolent fashion.”


    Pancreatic neuroendocrine tumors: accurate grading with Ki-67 index on fine-needle aspiration specimens using the WHO 2010/ENETS criteria.
Farrell JM et al.
Cancer Cytopathol. 2014 Oct;122(10):770-8.
  • “These results indicate that EUS-FNA cytology samples can be accurately graded based on the WHO Ki-67 labeling scheme. Thus, Ki-67 scoring in EUS-FNA cytology samples is an alternative approach for establishing the grade of panNETs. Accurate grading of panNETs is critical for predicting tumor biology, patient prognosis, and making informed decisions regarding patient management and treatment.”


    Pancreatic neuroendocrine tumors: accurate grading with Ki-67 index on fine-needle aspiration specimens using the WHO 2010/ENETS criteria.
Farrell JM et al.
Cancer Cytopathol. 2014 Oct;122(10):770-8.
  • “ The management of GEP-NETs has become complex, requiring a multidisciplinary approach. The World Health Organization classification of GEP-NETs has been revised; the U.S. Food and Drug Administration has approved molecular targeted agents (sunitinib,everolimus) for the treatment of pancreatic NETs; and the National Comprehensive Cancer Network clinical practice guidelines have been updated.”
    Update on the Management of Gastroenteropancreatic Neuroendocrine Tumors with Emphasis on the Role of Imaging
    Kim KW et al.
    AJR 2013; 201:811-824
  • “ Radiologists in collaboration with oncologists, surgeons and pathologists should adopt a multidisciplinary therapeutic approach that includes use of imaging and clinicopathologic data for optimize, focused care of patients with GEP-NETs.”
    Update on the Management of Gastroenteropancreatic Neuroendocrine Tumors with Emphasis on the Role of Imaging
    Kim KW et al.
    AJR 2013; 201:811-824
  • Pancreatic Neuroendocrine Tumors (NET)
    - AKA “Islet cell tumors”
    - Composed of well differentiated endocrine cells
    - No longer categorized as “functioning” or “non-functioning”
    - All NETs are hormonally active
    - Now categorized as “syndromic” or “nonsyndromic” based on laboratory and clinical findings
  • Associations
    - Von Hippel-Lindau Disease
    - Retinal and CNS Hemangioblastomas
    - Pheochromocytomas
    - Serous Cystadenomas
    - Pancreatic neuroendocrine tumors
    - RCC
    - Neurofibromatosis Type I
    - Tuberous Sclerosis
    - MEN Type I Syndrome
    - Parathyroid hyperplasia or adenomas
    - Neuroendocrine tumors of pancreas or duodenum
    - Pituitary Adenomas
  • Syndromic NETs
    - Clinically evident lesions due to hormone production and endocrinopathy
    - Tend to present when smaller because of symptoms
    - Often secrete multiple hormones, but the most secreted hormone establishes the syndrome
    - Tend to be < 3 cm in size
    - Insulinoma, Gastrinoma, Glucagonoma, VIPoma, Somatostatinoma
  • Syndromic NETs
    - Two most common types:
    - Insulinoma:
    - Whipple triad: Fasting glucose < 50 mg/dl, symptomatic hypoglycemia, and symptom improvement after glucose
    - 10% MEN-I, 10% malignant
    - Tend to be small (< 2 cm)
    - Gastrinoma:
    - Most common NET in MEN-I
    - Zollinger-Ellison Syndrome
    - Peptic ulcer disease with ulcers in unusual locations (i.e. post-bulbar)
    - Often malignant (30% present with liver metastases)
    - Often multiple and can be extrapancreatic (“gastrinoma triangle”)
  • Nonsyndromic NET
    - Roughly 50% of all NETs
    - Tend to be larger because of lack of symptoms when smaller
    - Produce symptoms when larger due to mass effect, metastases, local invasion, etc.
    - Average size of over 5 cm
    - More likely to be cystic, necrotic, calcified, and aggressive in behavior
  • Imaging Appearance
    - Very well circumscribed
    - Avidly enhancing on the arterial phase, and typically vascular on the venous phase
    - Can rarely be more conspicuous on the venous phase
    - Rarely cystic or necrotic
    - Cystic lesion with hypervascular rim
    - Usually will not obstruct the pancreatic or biliary ducts
    - Exceptions are large tumors and small lesions secreting serotonin (causes fibrotic stricturing of the ducts)
    - No pancreatic atrophy
    - Hypervascular lymph nodes
  • Mimics of Pancreatic NET
    - Pancreatic Metastases (especially RCC)
    - Acinar Cell Carcinoma
    - Intrapancreatic Splenule
    - Peripancreatic GIST
    - Solid Serous Cystadenoma
    - Pancreatic Hamartoma
    - Peripancreatic Paraganglioma
  • “ These data suggest that serotonin produced by pancreatic endocrine neoplasms may be associated with local fibrosis and stenosis of the pancreatic duct. Clinicians should be aware that small pancreatic endocrine neoplasms can produce pancreatic duct stenosis resulting in ductal dilatation and/or upstream pancreatic atrophy out of proportion to the size of the tumor.”
    Pancreatic Duct Stenosis Secondary to Small Endocrine Neoplasms: A Manifestation of Serotonin Production?
    Shi C et al.
    Radiology 2010; 257:107-114
  • “ Clinicians should be aware that small pancreatic endocrine neoplasms can produce upstream ductal dilatation and/or pancreatic atrophy out of proportion to the size of the tumor.”
    Pancreatic Duct Stenosis Secondary to Small Endocrine Neoplasms: A Manifestation of Serotonin Production?
    Shi C et al.
    Radiology 2010; 257:107-114
  • What is the correct management of an incidental PNET-
    A. Conservative followup at 6 month intervals-
    B. No followup needed
    C. Immediate surgery with pancreatectomy
    D. It depends on other findings
  • “ Approximately 50% of incidental NETs show uncertain or malignant behavior. Solid tumors 3 cm or larger are commonly nonbenign; however, about 30% of tumors smaller than that size cutoff can be malignant. Nonbenign tumors and those with invasive features on MDCT have a higher incidence of recurrence.”
    Incidental Neuroendocrine Tumors of the Pancreas: MDCT Findings and Features of Malignancy
    Gallotti A et al.
    AJR 2013; 200:355-362
  • “ Other MDCT features such as the presence of vascular invasion, MPD dilatation, or peripancreatic lymph node enlargement are often associated with nonbenign tumors and show higher risk of recurrence.”
    Incidental Neuroendocrine Tumors of the Pancreas: MDCT Findings and Features of Malignancy
    Gallotti A et al.
    AJR 2013; 200:355-362
  • Neuroendocrine Tumors of the Pancreas: Facts
    - 75% of cases are sporadic, 25% of cases occur as part of genetic syndromes
    - Common age of occurrence is 5th-7th decade
    - Non-functioning tumors now make up 60-80% of lesions detected
    - Neuroendocrine tumors have malignant potential but biologic aggressiveness and metastasizing risk is variable
    - Surgery remains the treatment of choice
  • Neuroendocrine Tumors of the Pancreas: CT Findings
    - Lesions may be solid, cystic of mixed in appearance
    - Peripheral or central calcification may occur and these lesions are more likely malignant
    - Vascular invasion is consistent with malignant NET
    - extra-pancreatic findings include vascular liver metastases, peri-portal adenopathy, and vascular invasion
  • “Cystic pancreas NETs are not rare and should be included in the differential diagnosis of a cystic pancreatic mass particularly if the cystic mass is associated with peripheral contrast enhancement. A minority of cystic pancreatic NETs can present with no peripheral enhancement.”
    Pancreatic Neuroendocrine Tumor With Cystlike Changes: Evaluation with MDCT
    Kawamoto S, Johnson PT, Shi C, Singhi AD, Hruban RH, Wolfgang CL, Edil BH, Fishman EK
    AJR 2013; 200:W283-W290
  • “Peripheral contrst enhancement greater than normal pancreatic parenchyma was observed in 11 of 13 (85%) predominantly cystic tumors including one case of equivocal peripheral enhancement.”
    Pancreatic Neuroendocrine Tumor With Cystlike Changes: Evaluation with MDCT
    Kawamoto S, Johnson PT, Shi C, Singhi AD, Hruban RH, Wolfgang CL, Edil BH, Fishman EK
    AJR 2013; 200:W283-W290
  • “ Nonfunctioning pancreatic NETs were reported to be more prevalent than functioning pancreatic NETs and accounted for approximately 85% of all pancreatic NETs.”
    Pancreatic Neuroendocrine Tumor With Cystlike Changes: Evaluation with MDCT
    Kawamoto S, Johnson PT, Shi C, Singhi AD, Hruban RH, Wolfgang CL, Edil BH, Fishman EK
    AJR 2013; 200:W283-W290
  • “ A dedicated CT protocol including arterial phase imaging is essential to detect peripheral contrast enhancement.”
    Pancreatic Neuroendocrine Tumor With Cystlike Changes: Evaluation with MDCT
    Kawamoto S, Johnson PT, Shi C, Singhi AD, Hruban RH, Wolfgang CL, Edil BH, Fishman EK
    AJR 2013; 200:W283-W290
  • Pancreatic Neuroendocrine Tumors: Associated Syndromes
    - Multiple endocrine neoplasia 1 (MEN 1)
    - Von Hippel Lindau (VHL) syndrome
    - Neurofibromatosis type I
  • “ The incidence of venous tumor thrombus detected by imaging was 33% in our study. This imaging finding was not accurately reported on the radiology report in 62% of the patients. In 18% of the patients with gross venous tumor thrombi, there was a significant alteration in the surgical plan. It is critical for the radiologist to be aware of the association of venous tumor thrombi in patients with nonfunctioning pancreatic neuroendocrine tumors and to report these findings.”
    Venous Tumor Thrombus in Nonfunctional Pancreatic Neuroendocrine Tumors
    Balachandran A et al.
    AJR 2012; 199:602-606
  • “ CT showed venous tumor thrombi in 29 of the 88 patients (33%). The CT finding was not accurately reported in 18 of the 29 patients (62%).”
    Venous Tumor Thrombus in Nonfunctional Pancreatic Neuroendocrine Tumors
    Balachandran A et al.
    AJR 2012; 199:602-606
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