Calcification and fibrosis in mesenteric carcinoid tumor: CT findings and pathologic correlation

Imaging of Small-Bowel Neuroendocrine Neoplasms: AJR Expert Panel Narrative Review

Neuroendocrine neoplasms (NENs) of the small bowel are typically slow-growing lesions that remain asymptomatic until reaching an advanced stage. Imaging modalities for lesion detection, staging, and follow-up in patients with known or suspected NEN include CT enterography, MR enterography, and PET/CT using a somatostatin receptor analog. FDG PET/CT may have a role in the evaluation of poorly differentiated NENs. Liver MRI, ideally with a hepatocyte-specific contrast agent, should be used in the evaluation of hepatic metastases. Imaging informs decisions regarding both surgical approaches and systematic therapy (specifically, peptide receptor radionuclide therapy). This AJR Expert Panel Narrative Review describes the multimodality imaging features of small-bowel NENs; explores the optimal imaging modalities for their diagnosis, staging, and follow-up; and discusses how imaging may be used to guide therapy.

Small bowel neuroendocrine neoplasm: what surgeons want to know

Neuroendocrine neoplasms of the small bowel are a diverse group of tumors with a broad spectrum of imaging findings and clinical implications. Most tumors originate in close proximity to the ileocecal valve and most commonly metastasize to the mesentery and liver. This review will highlight the imaging findings of primary and metastatic small bowel neuroendocrine neoplasm that are most relevant to the surgical team.

Aberrant tryptophan metabolism in stromal cells is associated with mesenteric fibrosis in small intestinal neuroendocrine tumors

BACKGROUND

Increased levels of serotonin secretion are associated with mesenteric fibrosis (MF) in small intestinal neuroendocrine tumors (SI-NETs). However, the profibrotic potential of serotonin differs between patients, and in this study, we aimed to gain an understanding of the mechanisms underlying this variability. To this end, we analyzed the proteins involved in tryptophan metabolism in SI-NETs.

METHODS

Proteomes of tumor and stroma from primary SI-NETs and paired mesenteric metastases of patients with MF (n = 6) and without MF (n = 6) were identified by liquid chromatography-mass spectrometry (LC-MS). The differential expression of proteins involved in tryptophan metabolism between patients with and without MF was analyzed. Concurrently, monoamine oxidase A (MAO-A) expression was analyzed in the tumor and stromal compartment by immunohistochemistry (IHC) and reported as intensity over area (I/A).

RESULTS

Of the 42 proteins involved in tryptophan metabolism, 20 were detected by LC-MS. Lower abundance of ten proteins was found in mesenteric metastases stroma in patients with MF. No differential expression was found in primary SI-NETs. In patients with MF, IHC showed lower MAO-A expression in the stroma of the primary SI-NETs (median 4.2 I/A vs 6.5 I/A in patients without MF, P = 0.003) and mesenteric metastases (median 2.1 I/A vs 2.8 I/A in patients without MF, P= 0.019).

CONCLUSION

We found a decreased expression of tryptophan and serotonin-metabolizing enzymes in the stroma in patients with MF, most notably in the mesenteric stroma. This might account for the increased profibrotic potential of serotonin and explain the variability in the development of SI-NET-associated fibrotic complications.

Sexual Dimorphism in Small-intestinal Neuroendocrine Tumors: Lower Prevalence of Mesenteric Disease in Premenopausal Women

CONTEXT

Small-intestinal neuroendocrine tumors (SI-NETs) have a modest but significantly higher prevalence and worse prognosis in male patients.

OBJECTIVE

This work aims to increase understanding of this sexual dimorphism in SI-NETs.

PATIENTS AND METHODS

Retrospectively, SI-NET patients treated in a single tertiary center were included and analyzed for disease characteristics. Estrogen receptor 1 (ESR1) and 2 (ESR2), progesterone receptor (PGR), and androgen receptor (AR) messenger RNA (mRNA) expression was assessed in primary tumors and healthy intestine. Estrogen receptor alpha (ERα) and AR protein expression were analyzed by immunohistochemistry in primary tumors and mesenteric metastases.

RESULTS

Of the 559 patients, 47% were female. Mesenteric metastasis/fibrosis was more prevalent in men (71% / 46%) than women (58% / 37%; P = 0.001 and P = 0.027, respectively). In women, prevalence of mesenteric metastases increased gradually with age from 41.1% in women <50 years to 71.7% in women >70 years. Increased expression of ESR1 and AR mRNA was observed in primary tumors compared to healthy intestine (both P < 0.001). ERα staining was observed in tumor cells and stroma with a strong correlation between tumor cells of primary tumors and mesenteric metastases (rho = 0.831, P = 0.02), but not in stroma (rho = -0.037, P = 0.91). AR expression was only found in stroma.

CONCLUSION

Sexual dimorphism in SI-NETs was most pronounced in mesenteric disease, and the risk of mesenteric metastasis in women increased around menopause. The combination of increased ERα and AR expression in the SI-NET microenvironment suggests a modulating role of sex steroids in the development of the characteristic SI-NET mesenteric metastasis and associated fibrosis.

Metal peroxides for cancer treatment

In recent years, metal peroxide (MO2) such as CaO2 has received more and more attention in cancer treatment. MO2 is readily decompose to release metal ions and hydrogen peroxide in the acidic tumor microenvironment (TME), resulting metal ions overloading, decreased acidity and elevated oxidative stress in TME. All of these changes making MO2 an excellent tumor therapeutic agent. Moreover, by combining MO2 with photosensitizers, enzymes or Fenton reagents, MO2 can assist and promote various tumor therapies such as photodynamic therapy and chemodynamic therapy. In this review, the synthesis and modification methods of MO2 are introduced, and the representative studies of MO2-based tumor monotherapy and combination therapy are discussed in detail. Finally, the current challenges and prospects of MO2 in the field of tumor therapy are emphasized to promote the development of MO2-based cancer treatment.

Transcriptomic Profiling of In Vitro Tumor-Stromal Cell Paracrine Crosstalk Identifies Involvement of the Integrin Signaling Pathway in the Pathogenesis of Mesenteric Fibrosis in Human Small Intestinal Neuroendocrine Neoplasms

Aim

Analysis of the pathophysiology of mesenteric fibrosis (MF) in small intestinal neuroendocrine tumors (SI-NETs) in an in vitro paracrine model and in human SI-NET tissue samples.

Methods

An indirect co-culture model of SI-NET cells KRJ-I and P-STS with stromal cells HEK293 was designed to evaluate the paracrine effects on cell metabolic activity, gene expression by RT2 PCR Profilers to analyse cancer and fibrosis related genes, and RNA sequencing. The integrin signaling pathway, a specific Ingenuity enriched pathway, was further explored in a cohort of human SI-NET tissues by performing protein analysis and immunohistochemistry.

Results

RT Profiler array analysis demonstrated several genes to be significantly up- or down-regulated in a cell specific manner as a result of the paracrine effect. This was further confirmed by employing RNA sequencing revealing multiple signaling pathways involved in carcinogenesis and fibrogenesis that were significantly affected in these cell lines. A significant upregulation in the expression of various integrin pathway – related genes was identified in the mesenteric mass of fibrotic SI-NET as confirmed by RT-qPCR and immunohistochemistry. Protein analysis demonstrated downstream activation of the MAPK and mTOR pathways in some patients with fibrotic SI-NETs.

Conclusion

This study has provided the first comprehensive analysis of the crosstalk of SI-NET cells with stromal cells. A novel pathway – the integrin pathway – was identified and further validated and confirmed in a cohort of human SI-NET tissue featured by a dual role in fibrogenesis/carcinogenesis within the neoplastic fibrotic microenvironment.

Primary versus secondary nature of mesenteric neuroendocrine tumours

Neuroendocrine tumours (NETs) are rare group of malignancy that originate from neuroendocrine cells present throughout the body. Most patients with NET first present with symptoms associated with metastasis, and up to 20% of patients have unknown primary site of tumour. Most common metastatic sites for small intestine NETs (SI-NETs) are the locoregional lymph nodes and liver. Although mesenteric metastasis through direct extension or lymphatic spread from SI-NETs is common, mesenteric extranodal involvement is extremely rare, and its biology and primary versus secondary nature are not well understood. Due to their small size and location, SI-NETs are frequently undetected on anatomical imaging or indium-111-pentetreotide single-photon emission computed tomography/CT (Octreoscan) and are difficult to be found via endoscopy. Gallium-68-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-octreotate positron emission tomography (⁶⁸Ga-DOTATATE PET)/CT has been increasingly used for accurate staging, unknown primary tumour site localisation and appropriate management planning. We present a case of an incidentally found mesenteric NET with occult SI-NETs localised preoperatively by ⁶⁸Ga-DOTATATE PET/CT.

Evolution of the Mesenteric Mass in Small Intestinal Neuroendocrine Tumours

Simple Summary

Around two-thirds of patients with small intestinal neuroendocrine tumours are present with a metastatic mesenteric mass. This mass is known to cause intestinal complications, however, little is known on its development over time in the era of targeted therapy. Therefore, we conducted a retrospective study to assess the growth and response to therapy. We found that the growth of the mesenteric mass was detectable in 13.5% over a median time of 3.4 years and peptide receptor radionuclide therapy resulted in size reduction in only 3.8%. This site-specific static growth behavior is important to note when assessing disease progression and therapeutic options.

Abstract

Background: A metastatic mesenteric mass is a hallmark of small intestinal neuroendocrine tumours (SI-NETs). However, little is known on its development over time. Therefore, we conducted a study to assess the evolution of a SI-NET-associated mesenteric mass over time. Methods: Retrospectively, 530 patients with proven SI-NET were included. The presence and growth of a mesenteric mass was assessed using RECIST 1.1 criteria on every consecutive CT-scan until the end of follow-up or resection. Results: At baseline, a mesenteric mass was present in 64% of the patients, of whom 13.5% showed growth of the mesenteric mass with a median time to growth of 40 months. Male gender was the only independent predictor of growth (OR 2.67). Of the patients without a mesenteric mass at the first evaluation, 2.6% developed a pathological mesenteric mass. Treatment with peptide receptor radionuclide therapy (PRRT; N = 132) resulted in an objective size reduction of the mesenteric mass in 3.8%. Conclusion: The metastatic mesenteric mass in SI-NETs has a static behavior over time. Therefore, site-specific growth behavior should be taken into account when selecting target lesions and assessing disease progression and therapeutic response. PRRT appears not to be effective for size reduction of the mesenteric mass.

A 13th-century cystic echinococcosis from the cemetery of the monastery of Badia Pozzeveri (Lucca, Italy)

OBJECTIVE

To differentially diagnose a calcified formation recovered from a 13th century AD grave from the Tuscan monastery of Badia Pozzeveri, Lucca, Italy.

MATERIALS

A calcified formation from the thoraco-abdominal region of a skeleton buried in the monastery cemetery.

METHODS

Cone Beam Computed Tomography, Scanning Electron Microscope and Energy Dispersive X-Ray Spectroscopy.

RESULTS

A hollow, calcified ovoid formation was identified as typical of a hydatid cyst, permitting the diagnosis of cystic echinococcosis in a 35-45year-old female.

CONCLUSIONS

The study reveals the circulation of the parasite Echinococcus granulosus in the region of Lucca in late medieval Tuscany.

SIGNIFICANCE

This finding is the fourth case of cystic echinococcosis from an archaeological context in Italy and provides insight into environmental conditions that appear to have affected members of a community, irrespective of social status.

LIMITATIONS

Caution and the application of multiple analyses must be exercised in the differential diagnosis to discriminate among calcified formations.

SUGGESTIONS FOR FURTHER RESEARCH

Analysis of stable isotopes of the calcified formation, such as ¹⁵N and ¹³C, in order to compare them with isotopic values of the host individual and to further confirm the parasitic origin of the find.

Value of High-resolution MRI in Detecting Lymph Node Calcifications in Patients with Rectal Cancer

RATIONALE AND OBJECTIVES

To analyze CT and high-resolution MRI findings of nodal metastasis calcifications and determine the value of high-resolution MRI in detecting nodal calcifications in rectal cancer patients.

MATERIALS AND METHODS

In total, 229 rectal cancer patients were included. The CT was reviewed for the presence of nodal calcifications by two radiologists. High-resolution two-dimensional turbo spin-echo T2-weighted imaging (2D-TSE-T2WI) and fat-suppressed gadolinium-enhanced isotropic high-resolution three-dimensional gradient-echo T1-weighted imaging (3D-GRE-T1WI) were independently reviewed for nodal calcifications by the two radiologists at one-month and two-month intervals, respectively. The sensitivities, specificities and accuracies of the two high-resolution MRI in detecting nodal calcifications were calculated using CT results as a reference.

RESULTS

Regional calcified metastatic lymph nodes were found in 28 patients. The node-to-node evaluation revealed that 55 (98.2%) of the 56 calcified lymph nodes were metastatic. Fifty-one (92.7%) calcified metastatic lymph nodes displayed scattered fine punctate calcifications to different degrees on CT. In both types of high-resolution MRI, the calcifications demonstrated a patchy area of markedly reduced signal intensity in corresponding areas that were larger than those on CT. The sensitivity and accuracy of fat-suppressed gadolinium-enhanced isotropic high-resolution 3D-GRE-T1WI were significantly higher than those of high-resolution 2D-TSE-T2WI (76.8% vs 58.9%, P = 0.013; 98.3% vs 97.9%, P = 0.007; respectively).

CONCLUSION

Metastatic nodal calcifications are characteristic imaging findings in rectal cancer. Calcifications are indicated by markedly reduced signal on high-resolution MRI, which will alert radiologists to scrutinize CT for nodal calcifications and aid in the accurate diagnosis of metastatic lymph nodes.

Unravelling the Mysteries of the Mesentery

The mesentery and its folds tether the small bowel loops to the posterior abdominal wall. It transmits nerves, vessels, and lymph ensconced in a fatty sponge layer wrapped in a thin glistening peritoneum, from and to the small bowel. Not only does this flexible dynamic fatty apron house various localized primary benign and malignant lesions, it is often involved in and gives an indication of generalized or systemic diseases in the body. An understanding of the anatomy, components, and function of the mesentery helps to classify mesenteric abnormalities. This further allows for characterizing radiological patterns and appearances specific to certain disease entities. Recent reviews of mesenteric anatomy have kindled new interest in its function and clinical applications, heralding the possibility of revision of its role in diseases of the abdomen.

Multimodality imaging features of desmoid tumors: a head-to-toe spectrum

Desmoid tumors (DTs) are a rare and biologically heterogeneous group of locally aggressive fibroblastic neoplasm: their biological behavior spectrum ranges from indolent to aggressive tumors. DTs are classified as intra-abdominal, extra-abdominal, and within the abdominal wall lesions.It is well known that abdominal and extra-abdominal DTs are associated with familial adenomatous polyposis (FAP) and Gardner syndrome. Possible risk factors are prior trauma/surgery, pregnancy, and oral contraceptives.There was a real revolution in the management of DT: from aggressive first-line approach (surgery and radiation therapy) to a more conservative one (systemic treatment and "wait-and-see policy").In these clinical settings, radiologists play an important role for assessing lesion resectability, evaluating recurrence, monitoring the biological behavior if an expectant management is chosen, and assessing response to systemic treatment as well as to radiation therapy.Awareness of common locations, risk factors, and imaging features is fundamental for a correct diagnosis and an adequate patient management.

Pathogenesis and Clinical Management of Mesenteric Fibrosis in Small Intestinal Neuroendocine Neoplasms: A Systematic Review

Mesenteric fibrosis (MF) constitutes an underrecognized sequela in patients with small intestinal neuroendocrine neoplasms (SI-NENs), often complicating the disease clinical course. The aim of the present systematic review, carried out by Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology, is to provide an update in evolving aspects of MF pathogenesis and its clinical management in SI-NENs. Complex and dynamic interactions are present in the microenvironment of tumor deposits in the mesentery. Serotonin, as well as the signaling pathways of certain growth factors play a pivotal, yet not fully elucidated role in the pathogenesis of MF. Clinically, MF often results in significant morbidity by causing either acute complications, such as intestinal obstruction and/or acute ischemia or more chronic conditions involving abdominal pain, venous stasis, malabsorption and malnutrition. Surgical resection in patients with locoregional disease only or symptomatic distant stage disease, as well as palliative minimally invasive interventions in advanced inoperable cases seem clinically meaningful, whereas currently available systemic and/or targeted treatments do not unequivocally affect the development of MF in SI-NENs. Increased awareness and improved understanding of the molecular pathogenesis of MF in SI-NENs may provide better diagnostic and predictive tools for its timely recognition and intervention and also facilitates the development of agents targeting MF.

Mesenteric Amyloidosis: Radiologic Imaging with Pathologic Correlation

Amyloidosis is a rare disease that is characterized by abnormal deposition of amyloid proteins in tissues, resulting in local, or systemic disease. When localized, it can present as an amyloidoma. We report a case of mesenteric amyloidosis in an 80-year-old male who was found to have an incidental mesenteric mass that was biopsy-proven to represent non-light chain amyloid tissue.

Neuroendocrine tumors of the gallbladder

A gallbladder neuroendocrine neoplasm (GB-NEN) is a unique heterogeneous neoplasm, originating from neuroendocrine cells and able to secrete peptides as its neurotransmitter. Among all the neuroendocrine tumors (NETs), the GB-NEN prevalence is 0.5%, which accounts for ~2.1% of all gallbladder tumors. The current study aimed to present an up-to-date review of the clinical features, diagnosis and treatment of NETs of the gallbladder. A systematic literature search was performed in order to identify all relevant studies published. Thus far, the etiology and pathogenesis of GB-NEN remains unclear. Moreover, an ambiguous clinical manifestation exists as observed during laboratory examinations. As GB-NEN is a rare gallbladder lesion and is seldom seen in clinical practice, there is a limited availability of review reports, and it is therefore often considered only as a case study. It is difficult to distinguish GB-NEN from other gallbladder diseases using imaging diagnostic techniques. Although chemotherapy treatment provides prolonged progression-free survival, surgery is considered the best option. Thus, to overcome the inherent risks or shortfalls of traditional surgery; early detection, diagnosis and treatment of GB-NEN are required to improve patient longevity.

Workup of Gastroenteropancreatic Neuroendocrine Tumors

Neuroendocrine tumors of the gastrointestinal tract or pancreas are rare. Their presentation overlaps with other intra-abdominal neoplasms, but can have unique features. The workup involves recognition of unusual clinical features associated with the tumors, imaging, analysis of blood or urine concentrations, and biopsy. Functional imaging takes advantage of the neuroendocrine tumor-specific expression of somatostatin receptors. There are characteristic features supporting the diagnosis on contrast-enhanced cross-sectional imaging. The use of tumor markers for biochemical diagnosis requires an understanding of the confounding variables affecting these assays. There are unique and specific immunohistochemical staining and grading requirements for appropriate diagnosis of these tumors.

Clinicopathological correlations of mesenteric fibrosis and evaluation of a novel biomarker for fibrosis detection in small bowel neuroendocrine neoplasms

PURPOSE

Mesenteric fibrosis (MF) in small intestinal neuroendocrine neoplasms (SINENs) is often associated with significant morbidity and mortality. The detection of MF is usually based on radiological criteria, but no previous studies have attempted a prospective, multidimensional assessment of mesenteric desmoplasia to determine the accuracy of radiological measurements. There is also a lack of non-invasive biomarkers for the detection of image-negative MF.

METHODS

A multidimensional assessment of MF incorporating radiological, surgical and histological parameters was performed in a prospective cohort of 34 patients with SINENs who underwent primary resection. Pre-operative blood samples were collected in 20 cases to evaluate a set of five profibrotic circulating transcripts-the "fibrosome"-that is included as an "omic" component of the NETest.

RESULTS

There was a significant correlation between radiological and surgical assessments of MF (p < 0.05). However, there were several cases of image-negative MF. The NETest-fibrosome demonstrated an accuracy of 100% for the detection of microscopic MF.

CONCLUSIONS

The detection of MF by radiological criteria has limitations. The NETest-fibrosome is a promising biomarker for fibrosis detection and further validation of these results would be needed in larger, multicentre studies.

Disorders of neural crest derivates in oncoradiological practice

Hundreds of articles discuss the imaging characteristics and molecular background of prominent gastrointestinal (GI) motility disorders and tumors of the peripheral nervous system, but according to our knowledge an article focusing on the classification and developmental background of these heterogeneous diseases is not to be found. Our aim is to give insight on the common features of several diseases and tumors, starting with their common source of origin, the neural crest (NC). The NC is a transient cell population of the embryo, which differentiates into several organs/structures of our body (sympathetic trunk, adrenal medulla). Although the incidence of the individual tumors of NC cells is not high by themselves, the summation of these incidences may be relevant in the daily routine. In the introduction we mention the most prominent developmental routes and molecular pathways of NC cells, which is crucial to understand the pathogenesis and the wide range of involved cell types from the colon to the adrenal gland. We summarized the most important, useful pathological findings and imaging techniques from the X-ray to the positron emission tomography—computed tomography (CT) in order to help the identification of these diseases. This article may help to better understand NC lineage and its unique, diverse role during ontogeny, which may influence the radiologists to change several convictions, or understand better the background and/or connections of a wide range of tumors and syndromes.

CT detection of primary and metastatic ileal carcinoid tumor: rates of missed findings and associated delay in clinical diagnosis

PURPOSE

To determine the rate of missed CT findings of ileal carcinoid tumor prior to pathologic diagnosis and the resultant diagnostic delay.

METHODS

Initially, 74 patients with abdominal and pelvic CT prior to pathologically-proven diagnosis of ileal carcinoid were identified. Patients were excluded when the original CT study (n = 6) or report (n = 4) was not available, resulting in a final cohort of 64 patients (mean age, 58.3 years; 29 M/35F); 27 (42%) patients had more than one abdominal CT prior to diagnosis. All available CT studies prior to diagnosis were retrospectively reviewed for the presence of the primary ileal tumor and metastatic disease (mesenteric and hepatic).

RESULTS

Primary ileal tumors were prospectively missed on at least one CT scan in 64% (32/50) of patients with retrospectively identifiable disease. CT findings of mesenteric spread were missed at least once in 46% (25/54) of cases where present in retrospect. By the final pre-operative CT, hepatic metastases and bowel wall thickening were present in 55% (35/64) and 52% (33/64) of cases, respectively. In patients with missed ileal and/or mesenteric findings resulting in diagnostic delay, mean delay was 40 months (range 4-98 months).

CONCLUSION

Initial presentation of ileal carcinoid tumor, even with mesenteric involvement, is often missed prospectively at abdominal CT, leading to delay in diagnosis until bowel or mesenteric findings become more obvious, or hepatic metastatic disease manifests. Radiologists should make a concerted effort to evaluate the bowel and mesentery in patients with long-standing vague abdominal symptoms.

Multimodality imaging of small bowel neoplasms

Although the small intestine accounts for over 90% of the surface area of the alimentary tract, tumors of the small intestine represent less than 5% of all gastrointestinal tract neoplasms. Common small bowel tumors typically are well evaluated with cross-sectional imaging modalities such as CT and MR, but accurate identification and differentiation can be challenging. Differentiating normal bowel from abnormal tumor depends on imaging modality and the particular technique. While endoscopic evaluation is typically more sensitive for the detection of intraluminal tumors that can be reached, CT and MR, as well as select nuclear medicine studies, remain superior for evaluating extraluminal neoplasms. Understanding the imaging characteristics of typical benign and malignant small bowel tumors is critical, because of overlapping features and associated secondary complications.

Multimodality Imaging of Ileal Neuroendocrine (Carcinoid) Tumor

OBJECTIVE. The purpose of this article is to provide a multimodality imaging review of ileal carcinoid tumor. CONCLUSION. Ileal carcinoid tumors display a variety of radiologic findings. Delay in diagnosis is common because of initial nonspecific symptoms and subtle imaging findings. Reviewing the multimodality imaging appearance of the primary tumor, metastatic disease, and associated ancillary findings can help improve patient care.

Hepatic neuroendocrine tumors: gadoxetic acid-enhanced magnetic resonance imaging findings with an emphasis on differentiation between primary and secondary tumors

PURPOSE

To describe the findings of magnetic resonance (MR) imaging of hepatic neuroendocrine tumors (hNET) and to identify the features that differentiate secondary from primary tumors.

METHODS

This retrospective study was approved by the institutional review board, and the requirement for informed consent was waived. Between August 2008 and December 2014, 50 patients with pathologically proven hNETs who underwent gadoxetic acid-enhanced MR imaging with diffusion-weighted images were included. The patients were divided into two groups according to whether they had primary (n = 17) or secondary (n = 33) hNETs. Qualitative values based on a consensus between two observers [morphologic findings, signal intensity, and enhancement pattern (poor or indeterminate; hepatocellular carcinoma-like or cholangiocarcinoma-like)], and quantitative values (apparent diffusion coefficient) were evaluated as predictors of secondary hNETs using multivariable logistic regression and receiver operating characteristic (ROC) analysis.

RESULTS

In multivariate analysis, the presence of multiple lesions (p = 0.011), a tumor size less than 6.3 cm (p = 0.001), and a hepatocellular carcinoma-like enhancement pattern (p = 0.031) were significant independent factors for differentiating secondary from primary hNETs, and achieved a sensitivity of 91%, a specificity of 82%, and an accuracy of 88%, with a value of the area under the ROC curve of 0.931.

CONCLUSION

Using these specific MR imaging criteria, secondary hNETs could be differentiated from primary hNETs with a high degree of accuracy in patients with histopathologically proven hNETs.

Carcinoid syndrome: update on the pathophysiology and treatment

Approximately 30-40% of patients with well-differentiated neuroendocrine tumors present with carcinoid syndrome, which is a paraneoplastic syndrome associated with the secretion of several humoral factors. Carcinoid syndrome significantly and negatively affects patients' quality of life; increases costs compared with the costs of nonfunctioning neuroendocrine tumors; and results in changes in patients' lifestyle, such as diet, work, physical activity and social life. For several decades, patients with neuroendocrine tumors and carcinoid syndrome have been treated with somatostatin analogues as the first-line treatment. While these agents provide significant relief from carcinoid syndrome symptoms, there is inevitable clinical progression, and new therapeutic interventions are needed. More than 40 substances have been identified as being potentially related to carcinoid syndrome; however, their individual contributions in triggering different carcinoid symptoms or complications, such as carcinoid heart disease, remain unclear. These substances include serotonin (5-HT), which appears to be the primary marker associated with the syndrome, as well as histamine, kallikrein, prostaglandins, and tachykinins. Given the complexity involving the origin, diagnosis and management of patients with carcinoid syndrome, we have undertaken a comprehensive review to update information about the pathophysiology, diagnostic tools and treatment sequence of this syndrome, which currently comprises a multidisciplinary approach.

Neuroendocrine tumors of the small intestine causing a desmoplastic reaction of the mesentery are a more aggressive cohort

BACKGROUND

Desmoplastic reaction of the mesentery is commonly seen in patients with neuroendocrine tumors of the small intestine. However, it is not clear whether desmoplastic reaction is associated with tumor-specific characteristics and diminished prognosis. Therefore, the aim of this study was to investigate whether the presence of a desmoplastic reaction correlates with prognostic and molecular markers of neuroendocrine tumors of the small intestine.

METHODS

Patients with neuroendocrine tumors of the small intestine operated at our department from 2000 to 2016 were analyzed. Patient and tumor characteristics were evaluated. Kaplan-Meier and multivariate analyses were performed.

RESULTS

In total, 148 patients underwent surgery, and preoperative imaging was available in 113 patients. A total of 45 patients showed desmoplastic reaction of the mesentery and progression-free survival was significantly impaired (26 months versus 65.4 months) compared with patients without desmoplastic reaction. These patients had significantly more often distant metastases (84.4% vs 39.7%), lymphatic vessel (68.9% vs 44.1%), and perineural tissue infiltration (57.8% vs 17.6%) compared with patients without desmoplastic reaction. However, proliferation index (positive desmoplastic reaction 4.1% versus negative desmoplastic reaction 3.3%) and tumor size (positive desmoplastic reaction 2 cm versus negative desmoplastic reaction 1.9 cm) were not diverging significantly.

CONCLUSION

This study revealed that tumors leading to desmoplastic reaction are more aggressive, despite similar Ki67 indices.

Small intestinal neuroendocrine tumours and fibrosis: an entangled conundrum

Small intestinal neuroendocrine tumours (SI-NETs) are neoplasms characterized by their ability to secrete biogenic amines and peptides. These cause distinct clinical pathology including carcinoid syndrome, marked by diarrhoea and flushing, as well as fibrosis, notably mesenteric fibrosis. Mesenteric fibrosis often results in significant morbidity by causing intestinal obstruction, oedema and ischaemia. Although advancements have been made to alleviate symptoms of carcinoid syndrome and prolong the survival of patients with SI-NETs, therapeutic options for patients with mesenteric fibrosis are still limited. As improved insight in the complex pathogenesis of mesenteric fibrosis is key to the development of new therapies, we evaluated the literature for known and putative mediators of fibrosis in SI-NETs. In this review, we discuss the tumour microenvironment, growth factors and signalling pathways involved in the complex process of fibrosis development and tumour progression in SI-NETs, in order to elucidate potential new avenues for scientific research and therapies to improve the management of patients suffering from the complications of mesenteric fibrosis.

Mesenteric fibrosis and palliative surgery in small intestinal neuroendocrine tumours

Mesenteric fibrosis (MF) surrounding a mesenteric mass is a hallmark feature of small intestinal neuroendocrine tumours (SI-NETs). Since this can induce intestinal obstruction, oedema and ischaemia, prophylactic resection of the primary tumour and mesenteric mass is often recommended. This study assessed the predictors for mesenteric metastasis and fibrosis and the effect of MF and palliative surgery on survival. A retrospective analysis of 559 patients with pathologically proven SI-NET and available CT-imaging data was performed. Clinical characteristics, presence of mesenteric mass and fibrosis on CT imaging and the effect of palliative abdominal surgery on overall survival were assessed. We found that MF was present in 41.4%. Older age, 5-HIAA excretion ≥67 μmol/24 h, serum CgA ≥121.5 μg/L and a mesenteric mass ≥27.5 mm were independent predictors of MF. In patients ≤52 years, mesenteric mass was less often found in women than in men (39% vs 64%, P = 0.002). Corrected for age, tumour grade, CgA and liver metastasis, MF was not a prognostic factor for overall survival. In patients undergoing palliative surgery, metastasectomy of mesenteric mass or prophylactic surgery did not result in survival benefit. In conclusion, we confirmed known predictors of MF and mesenteric mass and suggest a role for sex hormones as women ≤52 years have less often a mesenteric mass. Furthermore, the presence of MF has no effect on survival in a multivariate analysis, and we found no benefit of metastasectomy of mesenteric mass or prophylactic surgery on overall survival.

Prognostic Factors for Survival among Patients with Small Bowel Neuroendocrine Tumours Associated with Mesenteric Desmoplasia

BACKGROUND

Small intestinal neuroendocrine tumours (SI NETs) represent 30-50% of small bowel neoplasms and are often associated with diverse fibrotic complications. Mesenteric fibrosis is a hallmark of SI NETs which may cause substantial morbidity and is considered an adverse feature. However, survival analyses in this group of patients are lacking.

METHODS

The aim of this retrospective study was to determine the overall survival (OS) and factors affecting prognosis in a large cohort of 147 patients with SI NETs and radiological evidence of mesenteric desmoplasia from our centre. The severity of desmoplasia was graded radiologically and its effect on OS and long-term complications was assessed. The median follow-up period was 82 months.

RESULTS

The median OS was 8.7 years (95% CI 6.8-9.9) with an overall 5-year survival of 71%. The univariate analysis demonstrated that an age >65 years, a liver tumour burden >50% of the hepatic parenchyma, carcinoid heart disease, chromogranin A levels >10 times the upper limit of normal, and urinary 5-hydroxyindoleacetic acid (5-HIAA) levels >5 times the upper limit of normal were poor prognosticators, while primary resection was associated with a longer OS. However, only an age >65 years and urinary 5-HIAA levels >10 times the upper limit of normal remained statistically significant after multivariate analysis. The severity of mesenteric desmoplasia did not seem to demonstrate a statistically significant relationship to OS or long-term outcomes.

CONCLUSION

This study is the first comprehensive survival analysis of patients with SI NETs associated with mesenteric desmoplasia and has provided important and clinically relevant epidemiological data for this group of patients.

Multimodality Imaging Findings in Carcinoid Tumors: A Head-to-Toe Spectrum

Carcinoid tumors are a rare biologically heterogeneous group of neuroendocrine tumors with a spectrum ranging from benign indolent to aggressive metastatic tumors. They belong to the category of amine precursor uptake and decarboxylase tumors, or apudomas. The most common sites for primary locations are the gastrointestinal and respiratory tracts; however, any organ can be involved. The clinical presentation depends on location, aggressiveness, production of biologically active amines and peptides, paraneoplastic syndromes, and tendency for metastasis. Their reported age-adjusted incidence has increased in recent years, partly due to improved detection at radiologic imaging and endoscopy. Not a ll neuroendocrine cell tumors are carcinoids. Numerous systems have been proposed regarding their nomenclature and classification. Cross-sectional and functional imaging plays an important role in diagnosis, lesion characterization, and staging. Awareness of nomenclature, classification, common sites of involvement, and imaging presentation are pivotal for making the diagnosis. Knowledge of the diverse clinical, pathologic, and radiologic spectrum of carcinoid tumors involving various organs of the body is important for diagnosis and patient management. ^©RSNA, 2017.

Pediatric Neuroendocrine Carcinoid Tumors: Review of Diagnostic Imaging Findings and Recent Advances

OBJECTIVE

Although rare, pediatric neuroendocrine tumors including carcinoid tumor have increased in incidence over the past few decades. Despite increased recognition, survival rates have not significantly improved. Earlier detection of these tumors is necessary to improve clinical outcomes. This article discusses imaging approaches for detecting pediatric carcinoid tumors including anatomic imaging methods such as CT and MRI as well as functional imaging methods targeting the somatostatin receptor including ¹¹¹In-labeled octreotide and newer ⁶⁸Ga-based radiotracers that may hold promise in hybrid PET/CT or PET/MRI.

CONCLUSION

Improvements in functional imaging with novel somatostatin receptor-specific radiotracers along with fused functional and anatomic imaging have substantially improved the clinical detection of carcinoid tumors. Although rare, these tumors are encountered in children, and an awareness of the appropriate use of various imaging methods is essential for pediatric specialists. Further research is needed to ascertain the diagnostic value of newer imaging methods and radiotracer-based treatment approaches, especially in the pediatric population.

Endoluminal contrast for abdomen and pelvis magnetic resonance imaging

Magnetic resonance (MR) imaging of the abdomen and pelvis can be limited for assessment of different conditions when imaging inadequately distended hollow organs. Endoluminal contrast agents may provide improved anatomic definition and detection of subtle pathology in such scenarios. The available routes of administration for endoluminal contrast agents include oral, endorectal, endovaginal, intravesicular, and through non-physiologic accesses. Appropriate use of endoluminal contrast agents requires a thorough understanding of the clinical indications, available contrast agents, patient preparation, and interaction of the contrast agent with the desired MR imaging protocol. For example, biphasic oral enteric contrast agents are preferred in MR enterography as their signal properties on T1- and T2-weighted imaging allow for evaluation of both intraluminal and bowel wall pathology. In specific situations such as with MR enterography, MR defecography, and accurate local staging of certain pelvic tumors, the use of an endoluminal contrast agent is imperative in providing adequate diagnostic imaging. In other clinical scenarios, the use of an endoluminal contrast agent may serve as an indispensable problem-solving tool.

De-misty-fying the mesentery: an algorithmic approach to neoplastic and non-neoplastic mesenteric abnormalities

Mesenteric abnormalities are often incidentally discovered on cross-sectional imaging performed during daily clinical practice. Findings can range from the vague "misty mesentery" to solid masses, and the possible etiologic causes encompass a wide spectrum of underlying pathologies including infectious, inflammatory, and neoplastic processes. Unfortunately, the clinical and imaging findings are often non-specific and may overlap. This article discusses the various diseases that result in mesenteric abnormalities. It provides a framework to non-invasively differentiate these entities, when possible.

Primary and secondary disease of the peritoneum and mesentery: review of anatomy and imaging features

The largest and most complex serosal membrane in the body, the peritoneum, lines the abdominal cavity, and the abdominopelvic viscera. It is frequently involved in a variety of benign and malignant processes. While secondary involvement of the peritoneum is more common, primary tumors can be a diagnostic challenge. Knowledge of the anatomy is crucial in understanding the various pathologic processes. Cross-sectional imaging plays an important role in diagnosing and evaluating the extent of the disease processes. This article reviews the imaging anatomy of the peritoneum and mesentery and the common pathologies involving it.

Metastatic Gastrointestinal Carcinoid Tumor with Unknown Primary Site

Carcinoid tumors are rare and slow growing malignancies derived from enterochromaffin cells. Two-thirds of carcinoid tumors arise in the gastrointestinal tract, and in 3% of these cases the primary site cannot be determined. Presenting symptoms depend on the location of the primary tumor but may be nonspecific, and in 13% of patients distant metastases are discovered on diagnosis. The classic carcinoid syndrome occurs in less than 10% of cases and only after metastasis to the liver. We present a case of a young woman with a gastrointestinal carcinoid tumor of unknown site that had metastasized to the liver. We also provide a review of the current diagnostic modalities. Familiarity with the signs and symptoms of carcinoid tumors and the diagnostic techniques thereof may facilitate early detection and improved outcome.

Mesenteric changes in an ultrasound examination can facilitate the diagnosis of neuroendocrine tumors of the small intestine

Neuroendocrine tumors make up an interesting pathology of a variable clinical picture, prognosis, localization, endocrine activity and degree of malignancy.

Role of computed tomography angiography in detection and staging of small bowel carcinoid tumors

Small-bowel carcinoid tumors are the most common form (42%) of gastrointestinal carcinoids, which by themselves comprise 70% of neuroendocrine tumors. Although primary small bowel neoplasms are overall rare (3%-6% of all gastrointestinal neoplasms), carcinoids still represent the second most common (20%-30%) primary small-bowel malignancy after small bowel adenocarcinoma. Their imaging evaluation is often challenging. State-of-the-art high-resolution multiphasic computed tomography together with advanced postprocessing methods provides an excellent tool for their depiction. The manifold interactive parameter choices however require knowledge of when to use which technique. Here, we discuss the imaging appearance and evaluation of duodenal, jejunal and ileal carcinoid tumors, including the imaging features of the primary tumor, locoregional mesenteric nodal metastases, and distant metastatic disease. A protocol for optimal lesion detection is presented, including the use of computed tomography enterography, volume acquisition, computed tomography angiography and three-dimensional mapping. Imaging findings are illustrated with a series of challenging cases which illustrate the spectrum of possible disease in the small bowel and mesentery, the range of possible appearances in the bowel itself on multiphase data and extraluminal findings such as the desmoplastic reaction in mesentery and hypervascular liver metastases. Typical imaging pitfalls and pearls are illustrated.

Squamous cell carcinoma in a capybara (Hydrochoerus hydrochaeris)

A 4-year and 2-month-old male capybara (Hydrochoerus hydrochaeris) was diagnosed with squamous cell carcinoma on the buttocks after chronic recurrent dermatosis. The capybara was euthanized, examined by computed tomography and necropsied; the tumor was examined histologically. Computed tomography showed a dense soft tissue mass with indistinct borders at the buttocks. Histological examination of the tumor revealed islands of invasive squamous epithelial tumor cells with a severe desmoplastic reaction. Based on the pathological findings, the mass was diagnosed as a squamous cell carcinoma. This is the first study to report squamous cell carcinoma in a capybara.

Imaging features of carcinoid tumors of the gastrointestinal tract

OBJECTIVE

Recent studies have provided a better understanding of the biologic behavior of gastrointestinal carcinoid tumors. This article focusing on imaging of gastrointestinal carcinoids will emphasize epidemiology, molecular biology, taxonomy, histopathology, and management.

CONCLUSION

Gastrointestinal carcinoids are a biologically heterogeneous group of tumors, with variable clinical presentation and biologic behavior. Imaging can play an important role in multidisciplinary identification and management of this disease.

Carcinoid tumors of the small-bowel: evaluation with 64-section CT-enteroclysis

PURPOSE

To describe the imaging presentation of carcinoid tumors of the small-bowel at 64-section CT-enteroclysis and determine the sensitivity of this technique for tumor detection.

PATIENTS AND METHODS

The 64-section CT-enteroclysis examinations of 22 patients with histopathologically proven small-bowel carcinoid tumors and those of 6 patients with suspected recurrence after small-bowel resection for carcinoid tumor were reviewed. Images were analyzed with respect to imaging presentation. Sensitivity, specificity, and accuracy, of 64-section CT-enteroclysis for the diagnosis of carcinoid tumor of the small-bowel were estimated with 95% confidence intervals (CIs).

RESULTS

Twenty-five carcinoid tumors were confirmed in 22 patients (prevalence, 22/28; 79%). Overall sensitivity for carcinoid tumor detection was 76% (19/25; 95%CI: 55-91%) on a per-lesion basis. On a per-patient basis, 64-section CT-enteroclysis had a sensitivity of 86% (19/22; 95%CI: 65-97%), a specificity of 100% (6/6; 95%CI: 54-100%) and an accuracy of 89% (25/28; 95%CI: 72-98%) for the diagnosis of carcinoid tumor. Focal small-bowel wall thickening, mesenteric stranding, and mesenteric mass were found in 20/22 (91%), 18/22 (82%) and 15/22 (68%) patients with pathologically confirmed tumors.

CONCLUSION

64-Section CT-enteroclysis shows highly suggestive features for the diagnosis of carcinoid tumor of the small-bowel and achieves high degrees of sensitivity for tumor detection.

Severe intestinal ischemia as a presenting feature of metastatic ileal carcinoid tumor: role of MDCT with coronal reformation in the early diagnosis

Intestinal ischemia is a rare but potentially fatal complication of mesenteric metastasis of intestinal carcinoid tumor and its mechanism isn't entirely clear. We present a case of intestinal ischemia secondary to metastatic ileal carcinoid tumor diagnosed by CT that showed a small mesenteric mass with an extensive desmoplastic reaction causing an intense involvement of the small bowel. Improvements in CT technology with the use of MDCT scanners and advanced reformatting capabilities play an important role in the early diagnosis and accurate recognition of this entity and its need for immediate treatment.

Radiological and nuclear medicine imaging of gastroenteropancreatic neuroendocrine tumours

Neuroendocrine tumours (NETs) comprise a heterogeneous group of neoplasms with very varying clinical expression. A functioning NET, for instance in the pancreas, may be very small and yet give rise to severe endocrine symptoms whereas a patient with a small bowel tumour may present with diffuse symptoms and disseminated disease with a palpable bulky liver. Imaging of NETs is therefore challenging and the imaging needs in the various patients are diverse. The basic modalities for NET imaging are computed tomography (CT) or magnetic resonance imaging (MRI) in combination with somatostatin receptor imaging (SMI) by scintigraphy with 111In-labelled octreotide (OctreoScan) or more recently by positron emission tomography (PET) with 68Ga-labelled somatostatin analogues. In this review these various morphological and functional imaging modalities and important methodological aspects are described. Imaging requirements for the various types of NETs are discussed and typical image findings are illustrated.