Diagnostic and Management Challenges in Vasoactive Intestinal Peptide Secreting Tumors: A Series of 15 Patients

Characteristics, therapy, and outcome of rare functioning pancreatic neuroendocrine neoplasms

Functioning pancreatic neuroendocrine neoplasms other than insulinomas and gastrinomas (rf-pNENs) are exceptionally rare tumours. Thus, their characteristics and long-term prognosis have not been well defined. This article aims to present data and experience from a single institution concerning this topic. Twelve of 216 (5.5%) patients with pNENs operated between 2002 and 2022 in the ENETS Centre of Excellence Marburg had rf-pNENs and their data were retrospectively analysed. We identified three vasoactive intestinal polypeptide producing pNENs, four glucagonomas and five calcitoninomas. The tumour could be visualised by preoperative imaging in all 12 patients, and six patients had distant metastases at the time of diagnosis. The tumour was located in the pancreatic tail in nine patients and the median tumour size was 82 (range 12-220) mm. Eleven patients underwent tumour resections (two robotic, nine conventional), nine of which were R0. After a median follow-up of 75 (range 1-247) months, six patients were alive, five of whom had no evidence of disease. All patients who remained disease-free had an initial R0 resection of the primary tumour and no initial liver involvement. This study sheds light on the distinct characteristics and outcomes of these exceedingly rare tumours, offering insights for improved understanding and management.

All you need to know about VIPoma: Review on the latest studies

Vasoactive intestinal peptide secreting tumor (VIPoma) is a rare mostly malignant neuroendocrine tumor that is characterized by watery diarrhea, hypokalemia and achlorhydria due to the nonregulated increased secretion of VIP. VIPomas ar diagnosed by the presence of the most common symptoms, laboratory analysis of blood and stool, radiological imaging and immunohistochemical findings. Primary treatment includes fluid replacement, electrolyte balance correction, pharmacological treatment with somatostatin analogs, surgical resection and chemotherapy. This review aims to provide an insight into the latest research on VIPoma epidemiology, pathophysiology, diagnostics and treatment.

Interference With VIP to Distinguish Between Real and False VIPoma: National Study From the French Endocrine Tumors Group

Background

Vasoactive intestinal peptide (VIP)-secreting tumors (VIPomas) are digestive neuroendocrine tumors in which the hormonal secretion is life-threatening. Biological confirmation is obtained by demonstrating an elevation in plasma VIP, usually using radioimmunoassay (RIA). In some cases, analytical interference is suspected. We developed 3 different techniques to detect interference in VIP RIA.

Methods

Three techniques were used: RIA after Sephadex column chromatography separation, RIA after polyethylene glycol precipitation, and 125I-labeled VIP binding test. We included patients with suspicion of false positive VIP (FPV) elevation. We then compared results with those of a group of "real," proven VIPoma (RV).

Results

A total of 15 patients with FPV elevation and 9 RV patients were included. Interference was detected in all FPV patients vs none in RV. Clinical and biochemical parameters did not differ between FPV and RV patients, but VIP concentration in RIA was significantly higher in FPV patients than in RV patients (228 pmol/L vs 66 pmol/L, P = .038). Using a 125I-labeled VIP binding test, median proportion of radioactivity in the pellet was significantly higher in FPV than in RV patients (53% vs 13%, P < .0001). A 20.5% threshold presented excellent performances (sensitivity 100% [79.6-100], specificity 100% [70.1-100]).

Conclusion

We developed 3 different laboratory techniques to reveal interference in RIA VIP assays. The diagnostic performance of all 3 was excellent. These techniques must be employed in cases of discordance between VIP elevation and clinical presentation.

Contemporary Approaches to the Surgical Management of Pancreatic Neuroendocrine Tumors

The incidence of pancreatic neuroendocrine tumors (PNETs) is on the rise primarily due to the increasing use of cross-sectional imaging. Most of these incidentally detected lesions are non-functional PNETs with a small proportion of lesions being hormone-secreting, functional neoplasms. With recent advances in surgical approaches and systemic therapies, the management of PNETs have undergone a paradigm shift towards a more individualized approach. In this manuscript, we review the histologic classification and diagnostic approaches to both functional and non-functional PNETs. Additionally, we detail multidisciplinary approaches and surgical considerations tailored to the tumor's biology, location, and functionality based on recent evidence. We also discuss the complexities of metastatic disease, exploring liver-directed therapies and the evolving landscape of minimally invasive surgical techniques.

Pancreatic Vasoactive Intestinal Peptide-Producing Tumor as a Rare Cause of Acute Diarrhea and Severe Hypokalemia

Pancreatic vasoactive intestinal peptide-producing tumor (VIPoma) is a rare functional neuroendocrine tumor most commonly presenting with watery diarrhea and electrolyte abnormalities that include hypokalemia, hypercalcemia and metabolic acidosis. This type of tumor has usually insidious clinical behavior that is characterized by chronic secretory diarrhea, lasting usually from months to years before diagnosis, not responsive to usual medical or dietary treatment approaches. Given the resemblance of VIPoma with other more common causes of chronic watery diarrhea, the final diagnosis is often delayed and the tumors are usually large and metastatic at the time of detection. Our case of pancreatic VIPoma demonstrates an unusual clinical course for this type of tumor with acute refractory diarrhea and rapid deterioration of patient's clinical and biochemical status that required emergent in-hospital diagnosis and treatment. Our patient is a 45-year-old woman who presented with abrupt, watery diarrhea during the past 24 h before admission accompanied with severe hypokalemia as well as hyponatremia, hyperglycemia and hypercalcemia. Despite aggressive management with fluid administration and electrolyte replenishment, no significant improvement in patient's symptoms and electrolyte imbalance was observed. After exclusion of other causes of acute diarrhea from the medical history and the laboratory tests, the clinical suspicion of a functional neuroendocrine tumor was raised. After the establishment of final diagnosis of pancreatic VIPoma with biochemical tests and magnetic resonance imaging (MRI), somatostatin analogues were prescribed and the patient underwent distal pancreatectomy and splenectomy with no signs of lymph node and splenic metastases. Few days after the surgical resection of the tumor, the patient readmitted to our hospital with tarry stools and severe anemia. The abdominal computed tomography (CT) revealed a retroperitoneal cystic lesion. The gastrointestinal bleeding gradually recessed after endoscopic hemostasis of duodenal ulcer lesions whereas the cystic lesion (postoperative lymphocele) was successfully drained under CT-guidance before discharge. After almost 10 years postoperatively, the patient is still asymptomatic with no signs of relapse or metastasis of the disease in the periodic laboratory and imaging follow-up. In conclusion, pancreatic VIPoma can sometimes manifest symptoms of abrupt onset and rapid progression that require high clinical suspicion, appropriate diagnostic workup and aggressive management.

Chronic Diarrhea Caused by Vasoactive Intestinal Peptide-Secreting Tumor

VIPomas are a type of neuroendocrine tumor that independently produces vasoactive intestinal peptide (VIP). VIPomas causing watery diarrhea, hypokalemia, and achlorhydria (WDHA) syndrome are not frequently observed in adult patients without pancreatic ailments. However, in children, the occurrence of a VIPoma originating in the pancreas is exceedingly uncommon. Instead, WDHA syndrome is more commonly associated with neurogenic tumors that secrete VIP, often located in the retroperitoneum or mediastinum. Among infants, chronic diarrhea is a prevalent issue that often necessitates the attention of pediatric gastroenterologists. The underlying causes are diverse, and delays in arriving at a definitive diagnosis can give rise to complications affecting the overall well-being of the child. The authors present the case of an infant with chronic watery diarrhea, subocclusion manifestations, mild hypokalemia, and metabolic hyperchloremic acidosis secondary to a VIPoma in the retroperitoneum that was diagnosed via abdominal ultrasound and tomography. The laboratory results revealed lowered potassium levels and an excessive secretion of VIP. Following the surgical removal of the tumor, the diarrhea resolved, and both electrolyte levels and the imbalanced hormone levels returned to normal. Immunohistochemical examination confirmed the diagnosis of ganglioneuroblastoma, with N-MYC negative on molecular biology tests. We present the clinical and histo-genetic aspects of this rare clinical entity, with a literature review.

Effective strategies for adequate control of hormonal secretion in functioning neuroendocrine neoplasms

Neuroendocrine neoplasms are a unique form of malignancies as they can be accompanied by specific functioning hormonal syndromes that can impair survival and quality of life in patients. Functioning syndromes are defined by the combination of specific clinical signs and symptoms in combination with inappropriately elevated circulating levels of hormones. Clinicians should remain vigilant for the presence of functioning syndromes in neuroendocrine neoplasm patients at presentation as well as during follow-up. The correct diagnostic work-up should be initiated in cases of clinical suspicion of a neuroendocrine neoplasm-associated functioning syndrome. Management of a functional syndrome includes options from supportive, surgical, hormonal and antiproliferative treatment modalities. Here, we review the patient and tumour characteristics for each functioning syndrome that should be taken into account when deciding the optimum treatment strategy in neuroendocrine neoplasm patients.

Established and novel circulating neuroendocrine tumor biomarkers for diagnostic, predictive and prognostic use

The management of neuroendocrine tumors (NETs) represents a clinical challenge due to heterogeneity of their clinical behaviour, molecular biology and response to treatment. Over the years, several circulating biomarkers have been developed for the early diagnosis and follow-up of NETs. The specific secretory products of tumors associated with a secretory syndrome (functioning tumors) may be used as diagnostic and/or prognostic biomarkers while the most common non-specific circulating biomarkers, that may be increased in both functioning and non-functioning tumors, are chromogranin A and the neuron specific enolase. However, the diagnostic accuracy as well as the prognostic and predictive value of these biomarkers are limited and novel techniques of multianalyte analysis of regulators of tumor biology have been developed. The NETest has been most extensively studied and proved to be useful in NET diagnosis, early detection of post-operative recurrence and prediction of response to treatment but further investigation establishing higher level of evidence is required for implementation in clinical practice.

European Neuroendocrine Tumor Society 2023 guidance paper for functioning pancreatic neuroendocrine tumour syndromes

This ENETS guidance paper aims to provide practical advice to clinicians for the diagnosis, treatment and follow-up of functioning syndromes in pancreatic neuroendocrine tumours (NET). A NET-associated functioning syndrome is defined by the presence of a clinical syndrome combined with biochemical evidence of inappropriately elevated hormonal levels. Different hormonal syndromes can be encountered in pancreatic NET patients, including insulinoma, gastrinoma as well as the rare glucagonoma, VIPoma, ACTHoma, PTHrPoma, carcinoid syndrome, calcitoninoma, GHRHoma and somatostatinoma. The recommendations provided in this paper focus on the biochemical, genetic and imaging work-up as well as therapeutic management of the individual hormonal syndromes in well-differentiated, grade 1-3, functioning NET with the primary tumour originating in the pancreas, and for specific subtypes also in the duodenum.

A clinical analysis on functioning pancreatic neuroendocrine tumors (focusing on VIPomas): a single-center experience

VIPomas are generally rare functioning pancreatic neuroendocrine tumors (PanNETs) that cause watery diarrhea, hypokalemia, and achlorhydria. Due to their extreme rarity, the clinicopathological features and outcomes of VIPomas have not been well reported. This study aimed to determine the diagnostic and therapeutic characteristics and prognosis of VIPomas and to compare them with other PanNETs at a Japanese reference hospital. Medical records of 293 patients with PanNETs were collected. Patient and tumor characteristics and outcomes were retrospectively reviewed. This cohort had only 1.4% (four patients) of patients with VIPomas, and three of these patients changed from non-functioning (NF-) PanNETs during their disease course. Recurrences of hormonal symptoms were observed in all patients despite the initial controls, and all of them died from their disease, more specifically mainly from hormonal symptoms. Compared to the other PanNETs, VIPomas were all located at the pancreatic tail, were larger, and had a higher Ki-67 index and more metastasis. The median survival time was significantly shorter for patients with VIPoma than for those with NF-PanNET (5.9 vs. 26.7 years, p < 0.0001), insulinoma (21.8 years, p < 0.0001), and gastrinoma (12.3 years, p = 0.0325). This study presents the possibility of shifting from non-symptomatic to symptomatic VIPomas as they grow or of transforming from NF-PanNETs to VIPomas. VIPomas should be considered in patients with relatively large NF-PanNETs, especially those located in the pancreatic tail, when diarrhea is continuously observed. As hormonal symptoms are an important cause of death in VIPomas, long-term symptomatic control, which is relatively difficult, is of great significance.

Treatment options of metastatic and nonmetastatic VIPoma: a review

PURPOSE

VIPoma belongs to the group of neuroendocrine neoplasms. These tumours are located mostly in the pancreas and produce high levels of vasoactive intestinal peptide (VIP). In most cases, a metastatic state has already been reached at the initial diagnosis, with high levels of VIP leading to a wide spectrum of presenting symptoms. These symptoms include intense diarrhoea and subsequent hypopotassaemia but also cardiac complications, with life-threatening consequences. Treatment options include symptomatic therapy, systemic chemotherapy and targeted therapy, as well as radiation and surgery. Due to the low incidence of VIPoma, there are no prospective studies or evidence-based therapeutic standards to date.

METHODS

To evaluate the possible impact of different therapy strategies, we performed literature research using PubMed.

RESULTS

All possible treatment modalities for VIPoma have at least one of two therapy goals: antisecretory effects (symptom control) and antitumoural effects (tumour burden reduction). Symptomatic therapy is the most important in the emergency setting to rehydrate, balance electrolytes and stabilise the patient. Symptomatic therapy is also of great importance perioperatively. Somatostatin analogues play a major role in symptom control, although their efficiency is often limited. Chemotherapy may be effective in reaching stable disease for a certain time period, although its impact on symptom control is limited and often delayed. Among targeted therapy options, the usage of sunitinib appears to be the most effective in terms of symptom control and showing antitumoural effects at the same time. Experience with radiation is still limited; however, local ablative procedures seem to be promising options. Peptide receptor radiotherapy (PRRT) with radiolabelled somatostatin analogues (SSAs, 177Lu-DOTATATE) offers a targeted approach, especially in patients with high somatostatin receptor density. Surgery is the first-line therapy for nonmetastatic VIPoma. Additionally, if the resection of all visible tumour lesions is possible, the surgical approach seems preferable to other strategies in highly symptomatic patients. The role of surgery in very advanced stages where only tumour debulking is possible remains debatable. However, a high rate of immediate symptom control can be achieved by tumour debulking followed by somatostatin therapy, although the impact on survival remains unclear.

CONCLUSION

Surgery is the only curative option for nonmetastatic VIPoma. Additionally, surgery should be a first-line therapy option for highly symptomatic patients, especially if the resection of all tumour lesions (primary tumour and metastasis) is achievable. In frail patients, other modalities can be used.

Efficacy of treatments for VIPoma: A GTE multicentric series

BACKGROUND

Vasoactive intestinal peptide-secreting tumor (VIPoma) is a very rare, life-threatening, functioning pancreatic neuroendocrine tumor (pNET). The efficacy of antitumor therapies against functioning symptoms and tumor burden have been poorly described in VIPoma.

OBJECTIVE

Describe the impact of treatments on the secretory syndrome, tumor burden and survival in patients with VIPoma.

METHODS

We retrospectively reviewed the records of patients with VIPoma treated in seven French expert centers between 1990 and 2016. Diagnostic of VIPoma was reassessed using strict criteria. We evaluated the antisecretory efficacy (>50 % decrease of daily bowel movements), and antitumor efficacy (RECIST 1.1) of all treatments received.

RESULTS

Twenty-two patients were included. pNETs were mostly metastatic (77 %) and classified as grade 2 (83 %). Median follow-up was 78.2 months. Surgical excision of nonmetastatic VIPoma effectively controlled the secretory syndrome. Although 4/5 patients had metastatic recurrences, all patients were alive after median post-operative follow-up of 171 months. Among the 87 treatments received for metastatic VIPoma, curative-intent surgery (n = 14), somatostatin analogs alone (n = 11), chemotherapy (n = 23), transarterial liver embolization (TALE) (n = 14), everolimus (n = 10) and sunitinib (n = 7) achieved, respectively, 100 %, 67 %, 83 %, 50 %, 20 % and 100 % antisecretory efficacy. The 5-year OS rate was 63.6 %, with pejorative impact of higher Ki-67 index (P = 0.045) and higher plasma VIP concentration (P = 0.025).

CONCLUSIONS

Surgical resection of localized VIPoma is effective but rarely curative. For metastatic VIPoma, curative-intent surgery, chemotherapy and sunitinib are the therapeutic options that best combined antitumor and antisecretory efficacies.

VIPoma: a rare cause of diarrhea. A case report

Introduction: Vasoactive intestinal peptide-secreting tumor (VIPoma) is a rare functional pancreatic neuroendocrine tumor (F-PNET) characterized by secretory diarrhea, hypokalemia, and hypochlorhydria. Its low incidence and high risk of malignancy pose a clinical challenge that requires a high degree of clinical suspicion. Case presentation: A 61-year-old woman visited the emergency department of a tertiary care hospital in Medellín, Colombia, due to chronic diarrhea (7 months) that led to dehydration, renal failure, metabolic acidosis, and hypokalemia. As a result, a treatment based on loperamide, intravenous fluids and broad-spectrum antibiotics was started. In addition, chromogranin A levels of 477 ug/L (<100) were reported, while an abdominal MRI showed a 33x30mm mass in the head and uncinate process of the pancreas, so outpatient surgical management was decided. However, three days after discharge, and due to the persistence of clinical signs, the patient was admitted to another hospital (also a tertiary care hospital), where, given the high suspicion of VIPoma, and once the diarrhea was solved, the mass was removed (Whipple procedure) without any complication. Finally, the diagnosis was confirmed based on serum vasoactive intestinal peptide levels (930 pg/mL (RV<75)) and the pathology report (PNET tumor grade 2). Two years after the surgery, the patient was asymptomatic, and no residual lesions or metastases were evident in a control MRI. Conclusion: Late diagnosis of VIPoma is associated with worsened quality of life, severe complications, and high prevalence of metastasis. Therefore, it should be suspected in patients with chronic secretory diarrhea that is not caused by an infection, since early diagnosis and timely treatment can contribute to achieving better survival rates in these patients.

Perspectives on the current pharmacotherapeutic strategies for management of functional neuroendocrine tumor syndromes

Introduction: In the past, controlling the hormone-excess-state was the main determinant of survival in Functional-Neuroendocrine-Neoplasm-syndromes (F-NENs). This was difficult because the pharmacological-armamentarium available was limited. Recently, new therapeutic strategies have increased but it also generated controversies/uncertainties.Areas covered: The authors briefly review: established/proposed F-NENs; the rationale for treatments; the recommended initial-pharmacotherapeutic-approach to controlling F-NENs hormone-excess-state; the secondary-approaches if the initial approach fails or resistance develops; and the approach to deal with the malignant nature of the NEN. Also discussed are controversies/uncertainties related to new treatments.Expert opinion: Unfortunately, except for patients with insulinomas (>90-95%), gastrinomas (<20-40%), a minority with the other F-panNENs and 0-<1% with Carcinoid-syndrome is curative-surgery possible. Except for insulinomas, gastrinomas, and ACTHomas, long-acting somatostatin-analogs are the initial-pharmacological-treatments for hormone-excess-state. For insulinomas prior to surgery/malignancy, diazoxide is the initial drug-treatment; for gastrinomas, oral PPIs; and for ACTHomas, steroidogenesis inhibitors. There are now several secondary pharmacotherapeutic treatments. Surgery and liver-directed therapies also have a role in selected patients. Particularly promising is the recent results with PRRT for the hormone-excess-state, independent of its anti-growth effect. The sequence to use various agents and the approach to syndrome diagnosis while taking various agents remains unclear/controversial in many cases.

Surgical Management of Neuroendocrine Tumours of the Pancreas

Neuroendocrine tumours of the pancreas (pNET) are rare, accounting for 1-2% of all pancreatic neoplasms. They develop from pancreatic islet cells and cover a wide range of heterogeneous neoplasms. While most pNETs are sporadic, some are associated with genetic syndromes. Furthermore, some pNETs are 'functioning' when there is clinical hypersecretion of metabolically active peptides, whereas others are 'non-functioning'. pNET can be diagnosed at a localised stage or a more advanced stage, including regional or distant metastasis (in 50% of cases) mainly located in the liver. While surgical resection is the cornerstone of the curative treatment of those patients, pNET management requires a multidisciplinary discussion between the oncologist, radiologist, pathologist, and surgeon. However, the scarcity of pNET patients constrains centralised management in high-volume centres to provide the best patient-tailored approach. Nonetheless, no treatment should be initiated without precise diagnosis and staging. In this review, the steps from the essential comprehensive preoperative evaluation of the best surgical approach (open versus laparoscopic, standard versus sparing parenchymal pancreatectomy, lymphadenectomy) according to pNET staging are analysed. Strategies to enhance the short- and long-term benefit/risk ratio in these particular patients are discussed.

Rare Cases of Pediatric Vasoactive Intestinal Peptide Secreting Tumor With Literature Review: A Challenging Etiology of Chronic Diarrhea

Vasoactive intestinal peptide (VIP) secreting tumor (VIPoma) is a rare disease, presenting with profuse diarrhea, electrolyte imbalance, and possibly fatal outcome. The diagnosis and treatment are challenging, and no consensus guideline of management is available. The pediatric incidence remains unclear. This study comprises two pediatric case reports from a tertiary center and a literature-based case series investigating the characteristics among children. The two reported cases both presented with severe diarrhea and laboratory abnormalities, including electrolyte imbalance and elevated plasma VIP level. Case 1 received several imaging investigations, partial pancreatectomy, octreotide, and everolimus, reflecting her complicated and refractory course. Case 2 underwent total excision of suprarenal ganglioneuroblastoma, and the clinical response was significant. In both cases, varied degrees of symptomatic control, reduced plasma VIP level, and correction of electrolyte imbalance were achieved. A literature review-based case series analyzed 45 pediatric cases retrieved from the PubMed database until December 31, 2019. Demographics, clinical features, diagnostic modalities, treatments, and outcomes were presented.

Surgical management of pancreatic neuroendocrine tumors: an introduction

Introduction: Neuroendocrine tumors of the pancreas (pNETs) represent only 1% to 2% of all pancreatic neoplasms. These tumors can be classified as functional or nonfunctional tumors; as sporadic or from a genetic origin; as neuroendocrine neoplasms or carcinoma. Over the last decade, diagnosis of pNETs has increased significantly mainly due to the widespread use of cross-sectional imaging. Those tumors are usually associated with a good prognosis. Surgery, the only curative option for those patients, should always be discussed, ideally in a multidisciplinary team setting.Areas covered: We discuss i), the preoperative management of pNETs and the importance of accurate diagnosis, localization, grading and staging with computed tomography, magnetic resonance imaging, endoscopic ultrasound, and nuclear medicine imaging; ii), surgical indications and iii), the surgical approach (standard pancreatectomy vs pancreatic-sparing surgery).Expert opinion: The treatment option of all patients presenting with pNETs should be discussed in a multidisciplinary team setting with surgeon's experienced in both pancreatic surgery and neuroendocrine tumor management. A complete preoperative imaging assessment - morphological and functional - must be performed. Surgery is usually recommended for functional pNETs, nonfunctional pNETs >2 cm (nf-pNETs) or for symptomatic nf-pNETs.