Tumor thrombosis: a peculiar finding associated with pancreatic neuroendocrine neoplasms. A pictorial essay

Venous Thromboembolism in Patients with Neuroendocrine Neoplasms: A Systematic Review of Incidence, Types, and Clinical Outcomes

Background: Neuroendocrine neoplasms (NENs) are a heterogeneous group of tumors with unique biological characteristics and complications, including thromboembolism. This systematic review evaluates the incidence, types, and clinical outcomes of venous thromboembolic events (VTEs) in NEN patients. Methods: A systematic search of PubMed, Scopus, and Embase was conducted to identify studies on TEs in NENs. Eligible studies included case reports, case series, and retrospective cohort studies reporting VTEs, including deep vein thrombosis (DVT), pulmonary embolism (PE), and visceral vein thrombosis (VVT). Data were extracted on tumor site, functionality, differentiation grade, and VTE type. Results: In total, 33 studies were included, comprising 26 case reports, 2 case series, and 5 retrospective cohort studies. VTE prevalence ranged from 7.5% to 33% across studies. The most common VTEs were DVT, PE, and portal vein thrombosis (PVT). A meta-analysis revealed a pooled VTE prevalence of 11.1% (95% CI: 9.07-13.53%). Pancreatic NENs exhibited the highest thrombotic burden, particularly in poorly differentiated and advanced-stage tumors. Functioning tumors, including glucagonomas and ACTH-secreting NENs, were strongly associated with VTEs, potentially related to their systemic effects on coagulation and inflammation. Conclusions: Venous thromboembolism is a significant complication in NEN patients, especially in advanced or poorly differentiated tumors. Early detection and targeted management are critical for improving outcomes. Further investigations are required to clarify the mechanisms underlying thromboembolism in NENs and to develop optimized prophylactic and therapeutic strategies tailored to this patient population.

Revascularization techniques for complete portomesenteric venous occlusion in patients undergoing pancreatic resection

INTRODUCTION

Pancreatic pathologies causing portomesenteric occlusion complicate extirpative pancreatic resection due to portomesenteric hypertension and collateral venous drainage.

METHODS

Patients with portomesenteric occlusion undergoing pancreatectomy were identified between 2007 and 2020 at Stanford University Hospital. Demographic and clinical data, technique and perioperative factors, and post-operative outcomes were analyzed.

RESULTS

Of twenty-seven (27) patients undergoing venous revascularization during pancreatectomy, most (15) were for pancreatic neuroendocrine tumor. Occlusions occurred mostly at the portosplenic confluence (15). Median occlusion length was 4.0 cm [3.1-5.8]. Regarding revascularization strategy, mesocaval shunting was used in 11 patients, in-line venous revascularization with internal jugular conduit in three patients, traditional venous resection and reconstruction in 9 patients, and thrombectomy in two patients. Median cohort operative time and estimated blood loss were 522 min [433-638] and 1000 mL [700-2500], respectively. Median length of stay was 10 days [8-14.5] with overall readmission rate of 37%. Significant complications occurred in 44% of patients despite only one (4%) perioperative mortality.

DISCUSSION

Despite the technical complexity for managing portomesenteric occlusions, early revascularization strategies including mesocaval shunting or in-line venous revascularization are feasible and facilitate a safe pancreatic resection for surgically fit patients.

The Risk of Venous Thromboembolism in Neuroendocrine Neoplasms

Neuroendocrine neoplasms (NENs) differ from other malignancies in their ability to produce hormones and biogenic amines, as well as offer a better prognosis in well-differentiated tumors. There are no definite data on the occurrence of thromboembolic events in NENs and no recommendations regarding the use of antithrombotic prophylaxis in this group. Accurate assessment of the thromboembolic risk in NENs represents an important issue, in order to reduce morbidity and mortality due to complications of VTE. The aim of this work was to review the occurrence of thromboembolic events in NENs and the use of antithrombotic prophylaxis in this group. A total of 28 studies identified on PubMed were analyzed. NENs, especially of pancreatic primary, exhibit an increased thrombotic risk. Atypical VTE locations are quite common in NENs. Hormonally active NENs are associated with a significantly increased thromboembolic risk. Further studies in NENs are needed to evaluate the parameters of coagulation and fibrinolysis as predictive biomarkers for VTE complications.

Neuroendocrine neoplasm imaging: protocols by site of origin

With the relatively low incidence of neuroendocrine neoplasms (NEN), most radiologists are not familiar with their optimal imaging techniques. The imaging protocols for NENs should be tailored to the site of origin to accurately define local extension of NEN at time of staging. Patterns of spread and recurrence should be taken into consideration when choosing protocols for detection of recurrence and metastases. This paper will present the recommended CT and MRI imaging protocols for gastro-enteric and pancreatic NENs based on site of origin or predominant pattern of metastatic disease, and explain the rationale for MRI contrast type, contrast timing, as well as specific sequences in MRI. We will also briefly comment on PET/CT and PET/MRI imaging protocols.

Pancreatic neuroendocrine neoplasms: a 2022 update for radiologists

Pancreatic neuroendocrine neoplasms (PaNENs) are a unique group of pancreatic neoplasms with a wide range of clinical presentations and behaviors. Given their heterogeneous appearance and increasing detection on cross-sectional imaging, it is essential that radiologists understand the variable presentation and distinctions PaNENs display compared to other pancreatic neoplasms. Additionally, some of these neoplasms may be hormonally functional, and it is imperative that radiologists be aware of the common clinical presentations of hormonally active PaNENs. Knowledge of PaNEN pathology and treatments may influence which imaging modality is optimal for each patient. Each imaging modality used for PaNENs has distinct advantages and disadvantages, particularly in different treatment settings. Thus, the focus of this manuscript is to provide an update for the radiologist on PaNEN pathology, imaging, and treatments.

New frontiers in imaging including radiomics updates for pancreatic neuroendocrine neoplasms

OBJECTIVE

To illustrate the applications of various imaging tools including conventional MDCT, MRI including DWI, CT & MRI radiomics, FDG & DOTATATE PET-CT for diagnosis, staging, grading, prognostication, treatment planning and assessing treatment response in cases of pancreatic neuroendocrine neoplasms (PNENs).

BACKGROUND

Gastroenteropancreatic neuroendocrine neoplasms (GEP NENs) are very diverse clinically & biologically. Their treatment and prognosis depend on staging and primary site, as well as histological grading, the importance of which is also reflected in the recently updated WHO classification of GEP NENs. Grade 3 poorly differentiated neuroendocrine carcinomas (NECs) are aggressive & nearly always advanced at diagnosis with poor prognosis; whereas Grades-1 and 2 well-differentiated neuroendocrine tumors (NETs) can be quite indolent. Grade 3 well-differentiated NETs represent a new category of neoplasm with an intermediate prognosis. Importantly, the evidence suggest grade heterogeneity can occur within a given tumor and even grade progression can occur over time. Emerging evidence suggests that several non-invasive qualitative and quantitative imaging features on CT, dual-energy CT (DECT), MRI, PET and somatostatin receptor imaging with new tracers, as well as texture analysis, may be useful to grade, prognosticate, and accurately stage primary NENs. Imaging features may also help to inform choice of treatment and follow these neoplasms post-treatment.

CONCLUSION

GEP NENs treatment and prognosis depend on the stage as well as histological grade of the tumor. Traditional ways of imaging evaluation for diagnosis and staging does not yet yield sufficient information to replace operative and histological evaluation. Recognition of important qualitative imaging features together with quantitative features and advanced imaging tools including functional imaging with DWI MRI, DOTATATE PET/CT, texture analysis with radiomics and radiogenomic features appear promising for more accurate staging, tumor risk stratification, guiding management and assessing treatment response.

Surgical Indications and Outcomes of Resection for Pancreatic Neuroendocrine Tumors with Vascular Involvement

Simple Summary

Pancreatic neuroendocrine tumors (pNETs) are a heterogenous group of rare epithelial neoplasms. For most patients, surgery remains the only treatment modality to cure pNETs, and is recommended for patients with surgically resectable disease. Many of these tumors are non-functional tumors and do not produce clinical symptoms, so patients may present with locally advanced tumors, which invade surrounding organs or neighboring blood vessels. The presence of vascular involvement had previously been considered a contraindication to surgery, but, in recent years, at centers with considerable experience, aggressive surgery to remove pNETs with vascular reconstruction has been performed safely and with good long-term survival. In this review, we will discuss the considerations for resectability, review novel surgical approaches, and present the available evidence on the immediate and long-term postoperative outcomes.

Abstract

Complete surgical resection of pancreatic neuroendocrine tumors (pNETs) has been suggested as the only potentially curative treatment. A proportion of these tumors will present late during disease progression, and invade or encase surrounding vasculature; therefore, surgical treatment of locally advanced disease remains controversial. The role of surgery with vascular reconstruction in pNETs is not well defined, and there is considerable variability in the use of aggressive surgery for these tumors. Accurate preoperative assessment is critical to evaluate individual considerations, such as anatomical variants, areas and lengths of vessel involvement, proximal and distal targets, and collateralization secondary to the degree of occlusion. Surgical approaches to address pNETs with venous involvement may include thrombectomy, traditional vein reconstruction, a reconstruction-first approach, or mesocaval shunting. Although the amount of literature on pNETs with vascular reconstruction is limited to case reports and small institutional series, the last two decades of studies have demonstrated that aggressive resection of these tumors can be performed safely and with acceptable long-term survival.

Mesenteric Variceal Haemorrhage and Ectopic Cushing's Syndrome as Presenting Features of a Pancreatic Neuroendocrine Tumour Recurrence

Pancreatic neuroendocrine tumours can have varied and complex presentations. Whilst hormone hypersecretion often induces characteristic clinical syndromes, non-specific symptoms may arise due to localized tumour effects. Malignant invasion of local vasculature is an increasingly recognized complication of these neoplasms and can be associated with significant morbidity. Herein, we present the case of a 47-year-old male with a recurrence of a pancreatic neuroendocrine tumour who presented with unusual upper gastrointestinal bleeding. The tumour had recurred within the superior mesenteric vein, replacing the vessel and invading its branches. This resulted in porto-mesenteric hypertension and the formation of bleeding mesenteric varices. The patient subsequently developed progressive metabolic disturbances and was diagnosed with ectopic Cushing's syndrome, despite his primary tumour having been non-functional. This case demonstrates not only a rare pattern of tumour recurrence but also the potential for pancreatic neuroendocrine tumours to de-differentiate and change from non-functional to hormone secreting, a phenomenon which may complicate diagnosis and management.

Somatostatin-receptor avidity of pancreatic neuroendocrine tumor thrombus in porto-caval venous systems on 99mTc-Octreotide and posttherapeutic 177Lu-DOTA-TATE scans

A 62-year-old woman with a history of abdominal pain presented with multiple hepatic lesions and dilatation of portal, splenic and superior mesenteric veins on the magnetic resonance imaging referred for a 99mTc-octreotide scan. Accordingly, similar octreotide-avid lesions were found as well as an uptake in the epigastric region conforming to the anatomy of the portocaval venous system, compatible with a tumor thrombosis. Then, the patient underwent two cycles of therapy with 177Lu-DOTA-TATE, on that the same appearance was observed. The uptake in the tumor thrombus remained somewhat unchanged, but clinically, a significant improvement of the intractable ascites was achieved.

Patients With MEN1 Are at an Increased Risk for Venous Thromboembolism

BACKGROUND

Multiple endocrine neoplasia type 1 (MEN1) is a rare inherited disorder predisposing the development of multiple functional and nonfunctional neuroendocrine tumors (NETs). Only uncommon MEN1-associated functional NETs such as glucagonomas (<1%) and adenocorticotropic hormone-producing tumors (<5%) are known to be associated with hypercoagulability. It is unknown if patients with MEN1 generally have an increased risk of venous thromboembolism (VTE).

METHODS

We queried a prospective natural history study of germline mutation-positive MEN1 patients (n = 286) between 1991 and 2019 for all lifetime events of VTE. The search terms were: DVT, thromb, embol, PE, pulmonary embolism, clot, hematology consult, anticoagulant, coumadin, lovenox, xarelto, warfarin, aspirin, rivaroxaban, and apixaban. Incidence rates were calculated, accounting for age and sex. Comparisons were made to published incidence rates in healthy populations, different types of cancer, and Cushing's syndrome.

RESULTS

Thirty-six subjects (median age 45 years, range 16-75) experienced a VTE event, yielding a prevalence rate of 12.9%. The age-sex adjusted incidence rate of VTE is 9.11 per 1000 patient-years, with a sex-adjusted lifetime incidence rate of 2.81 per 1000 patient-years. MEN1-associated lifetime incidence rates are ~2-fold higher than the estimated annual incidence rate in the general population and are comparable to the known risk in the setting of various types of cancer. Approximately 80% of patients who had a VTE were diagnosed with pancreatic NETs, of which 24% were insulinomas. Fourteen patients (42%) experienced perioperative VTE events.

CONCLUSIONS

MEN1 patients have an increased risk of VTE. Further mechanistic investigation and validation from other MEN1 cohorts are needed to confirm the increased prevalence of VTE in MEN1.

Lynch syndrome-associated repeated stroke with MLH1 frame-shift mutation

Lynch syndrome (LS) is an autosomal dominant inherited disease caused by germline mutations in DNA mismatch repair (MMR) genes, including MLH1, MSH2, MSH6, and PMS2, which predisposes patients to various malignant neoplasms. Previous studies showed that MLH1, MSH2, MSH6, and PMS2 mutation in LS were associated with an elevated risk of colorectal, gastric, endometria, ovarian, and other cancers among family members. Patients of these kinds of cancers had high incidence of synchronous and metasynchronus. We describe the case of a 34-year-old female patient with 50 days of sudden dizziness and left limb weakness, whose head CT scan showed large infarction in the right frontal temporal parietal lobe and basal ganglia area. Imaging examinations and pathological biopsy indicated high-grade serous carcinoma (HGSC) IIIA1 of the right ovary. In addition, a novel frame-shift mutation in the MLH1 gene (c.1621dupG, p.A541Gfs*16) was found in the genetic panel sequence. It may render declining of MLH1 protein and also associate with the patient's progressive clinical manifestations of multiple systems. Therefore, the timely use of prenatal diagnosis to prevent unnecessary new cases of this severe genetic disease is available.

Rectal Neuroendocrine Tumor With Inferior Vena Cava Tumor Thrombosis Diagnosed With 68Ga-DOTANOC PET/CT

A 69-year-old man with a history of back pain, urinary obstruction, and deep vein thrombosis of both lower extremities 4 years earlier was diagnosed with rectal neuroendocrine tumor, grade 2, Ki-67 index 3%. Ga-DOTANOC PET/CT images showed a left pelvic mass extended to the lumen of the inferior vena cava with a high affinity for somatostatin receptor. A tubular focus of radiotracer accumulation after the course of inferior vena cava with filling defect was suggestive of tumor thrombus.

Extensive Tumor Thrombosis of Portal Venous System Demonstrated on 68Ga-DOTATATE and 68Ga-NODAGA-LM3 PET/CT in a Patient With Well-Differentiated Neuroendocrine Tumor

We present a case with a pancreatic neuroendocrine tumor and extensive tumor thrombosis in portal venous system. The tumor was first identified on contrast-enhanced CT and later confirmed using Ga-DOTATATE and Ga-NODAGA-LM3 PET/CT. Both tracers demonstrated similar pattern with higher tumor affinity and tumor-to-background ratio using Ga-NODAGA-LM3.

The role of multimodal imaging in guiding resectability and cytoreduction in pancreatic neuroendocrine tumors: focus on PET and MRI

Pancreatic neuroendocrine tumors (pNETs) are rare neoplasms that secrete peptides and neuro-amines. pNETs can be sporadic or hereditary, syndromic or non-syndromic with different clinical presentations and prognoses. The role of medical imaging includes locating the tumor, assessing its extent, and evaluating the feasibility of curative surgery or cytoreduction. Pancreatic NETs have very distinctive phenotypes on CT, MRI, and PET. PET have been demonstrated to be very sensitive to detect either well-differentiated pNETs using ⁶⁸Gallium somatostatin receptor (SSTR) radiotracers, or more aggressive undifferentiated pNETS using ¹⁸F-FDG. A comprehensive interpretation of multimodal imaging guides resectability and cytoreduction in pNETs. The imaging phenotype provides information on the differentiation and proliferation of pNETs, as well as the spatial and temporal heterogeneity of tumors with prognostic and therapeutic implications. This review provides a structured approach for standardized reading and reporting of medical imaging studies with a focus on PET and MR techniques. It explains which imaging approach should be used for different subtypes of pNET and what a radiologist should be looking for and reporting when interpreting these studies.

Macrovascular venous invasion of pancreatic neuroendocrine tumours: impact on surgical outcomes and survival

BACKGROUND

This study evaluates the impact of macrovascular venous invasion (MVI) on surgical and survival outcomes of pancreatic neuroendocrine tumours (PNETs).

METHODS

We retrospectively reviewed data of 125 patients operated for PNETs. Operative, pathological,and survival outcomes were compared between PNETs with and without MVI.

RESULTS

Macrovascular venous invasion was detected in 25 of 125 PNETs (20%) presenting as tumour thrombi (n = 12) or venous wall invasion (n = 13). MVI was associated with larger tumours, a higher rate of lymph node involvement, less differentiated tumours, and a higher rate of perineural invasion. Resection of PNETS with MVI more often necessitated combined hepatic, venous and multivisceral resections, had a higher rate of intraoperative blood transfusion (p = 0.04) but similar morbidity (44% vs. 42%) and mortality (0 vs. 1%) as PNETs without MVI. PNETs with MVI had a lower median overall survival rate (60 vs. 149 months; p = 0.03). Multivariate analysis revealed that PNETs of the pancreatic head, synchronous liver metastases and higher tumour grade were prognostic factors for overall survival.

CONCLUSIONS

MVI is found in more advanced PNETs. Resection of PNETs with MVI is characterized by increased transfusion rate and reduced overall survival.

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.