Cystic pancreatic neuroendocrine tumors: To date a diagnostic challenge

Imaging of pancreatic serous cystadenoma and common imitators

Pancreatic cystic neoplasms are lesions comprised of cystic components that show different biological behaviors, epidemiology, clinical manifestations, imaging features, and malignant potential and management. Benign cystic neoplasms include serous cystic neoplasms (SCAs). Other pancreatic cystic lesions have malignant potential, such as intraductal papillary mucinous neoplasms and mucinous cystic neoplasms. SCAs can be divided into microcystic (classic appearance), honeycomb, oligocystic/macrocystic, and solid patterns based on imaging appearance. They are usually solitary but may be multiple in von Hippel-Lindau disease, which may depict disseminated involvement. The variable appearances of SCAs can mimic other types of pancreatic cystic lesions, and cross-sectional imaging plays an important role in their differential diagnosis. Endoscopic ultrasonography has helped in improving diagnostic accuracy of pancreatic cystic lesions by guiding tissue sampling (biopsy) or cyst fluid analysis. Immunohistochemistry and newer techniques such as radiomics have shown improved performance for preoperatively discriminating SCAs and their mimickers.

Real-Life Management of Pancreatic Cysts: Simplified Review of Current Guidelines

Pancreatic cysts are becoming a popular diagnostic tool due to the increased availability of high-quality cross-sectional imaging. Pancreatic cystic lesions constitute closed, liquid-containing cavities, which are either neoplastic or non-neoplastic. While serous lesions often follow a benign course, mucinous lesions can hide carcinoma and, therefore, require different management. Moreover, all cysts should be considered mucinous until proven otherwise, thus limiting the errors in managing these entities. Due to the need for high contrast soft tissue imaging, magnetic resonance imaging represents an elective, non-invasive diagnostic tool. Endoscopic ultrasound (EUS) has started gaining more prominence with regard to the proper diagnosis and management of pancreatic cysts, offering quality information with minimal risks. Enabling both the acquisition of endoscopic images of the papilla and the endosonographic high-quality evaluation of septae, mural nodules along with the vascular patterns of the lesion contribute to a definitive diagnosis. Moreover, the possibility of obtaining cytological or histological samples could become mandatory in the foreseeable future, allowing for more precise molecular testing. Future research should focus on detecting methods to quickly diagnose high-grade dysplasia or early cancer for patients with pancreatic cysts, thus allowing time for appropriate treatment and avoiding surgical overtreatment or over surveillance in selected cases.

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.

Cystic Pancreatic Neuroendocrine Tumor: A Diagnostic Dilemma

Pancreatic neuroendocrine tumors are typically solid neoplasms but in rare instances may present as cystic lesions. Preoperative diagnosis of a cystic pancreatic lesion is challenging and requires a multidisciplinary and multimodal approach. We hereby describe an elderly female who came with complaints of abdominal lump. Radiologically, it appeared to be a pancreatic hydatid cyst located at the head of the pancreas, following which resection was done. Histopathological study of the lesion turned out to be a cystic pancreatic neuroendocrine tumor. Thus, we present this unique case due to its rarity and diagnostic challenge.

Total Pancreatectomy for Multicentric Cystic Neuroendocrine Tumor of the Pancreas: A Case Report

Pancreatic neuroendocrine tumors (PNETs) are uncommon pancreatic neoplasms with malignant potential, heterogeneous clinical behavior, as well as imaging appearance. These tumors represent less than 3% of all pancreatic neoplasms with typical CT presentation as solid, well-circumscribed, hypervascular lesions. Cystic PNET is a rare pancreatic tumor which is nowadays more often detected due to the widespread use of high-resolution cross-sectional imaging. They are mainly solitary lesions most commonly localized in the body and the tail of the pancreas. Due to cystic presentation these lesions often present a diagnostic challenge to both experienced radiologists and pathologists. Herein, we present a rare case of synchronous, multiple cystic and solid pancreatic neuroendocrine tumors, which due to their extensiveness required total dudenopancreatectomy with splenectomy. Histopathological findings confirmed microscopic and macroscopic cystic components as well as typical solid variants of neuroendocrine tumors along the entire pancreas.

Management of pancreatic cysts and guidelines: what the gastroenterologist needs to know

The prevalence of pancreatic cysts has increased significantly over the last decade, partly secondary to increased quality and frequency of cross-sectional imaging. While the majority never progress to cancer, a small number will and need to be followed. The management of pancreatic cysts can be both confusing and intimidating due to the multiple guidelines with varying recommendations. Despite the differences in the specifics of the guidelines, they all agree on several high-risk features that should get the attention of any clinician when assessing a pancreatic cyst: presence of a mural nodule or solid component, dilation of the main pancreatic duct (or presence of main duct intraductal papillary mucinous neoplasm), pancreatic cyst size ⩾3–4 cm, or positive cytology on pancreatic cyst fluid aspiration. Other important criteria to consider include rapid cyst growth (⩾5 mm/year), elevated serum carbohydrate antigen 19-9 levels, new-onset diabetes mellitus, or acute pancreatitis thought to be related to the cystic lesion.

Imaging of Pancreatic Neuroendocrine Neoplasms

Pancreatic neuroendocrine neoplasms (panNENs) represent the second most common pancreatic tumors. They are a heterogeneous group of neoplasms with varying clinical expression and biological behavior, from indolent to aggressive ones. PanNENs can be functioning or non-functioning in accordance with their ability or not to produce metabolically active hormones. They are histopathologically classified according to the 2017 World Health Organization (WHO) classification system. Although the final diagnosis of neuroendocrine tumor relies on histologic examination of biopsy or surgical specimens, both morphologic and functional imaging are crucial for patient care. Morphologic imaging with ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI) is used for initial evaluation and staging of disease, as well as surveillance and therapy monitoring. Functional imaging techniques with somatostatin receptor scintigraphy (SRS) and positron emission tomography (PET) are used for functional and metabolic assessment that is helpful for therapy management and post-therapeutic re-staging. This article reviews the morphological and functional imaging modalities now available and the imaging features of panNENs. Finally, future imaging challenges, such as radiomics analysis, are illustrated.

Cystic pancreatic lesions: MR imaging findings and management

Cystic pancreatic lesions (CPLs) are frequently casual findings in radiological examinations performed for other reasons in patients with unrelated symptoms. As they require different management according to their histological nature, differential diagnosis is essential. Radiologist plays a key role in the diagnosis and management of these lesions as imaging is able to correctly characterize most of them and thus address to a correct management. The first step for a correct characterization is to look for a communication between the CPLs and the main pancreatic duct, and then, it is essential to evaluate the morphology of the lesions. Age, sex and a history of previous pancreatic pathologies are important information to be used in the differential diagnosis. As some CPLs with different pathologic backgrounds can show the same morphological findings, differential diagnosis can be difficult, and thus, the final diagnosis can require other techniques, such as endoscopic ultrasound, endoscopic ultrasound-fine needle aspiration and endoscopic ultrasound-through the needle biopsy, and multidisciplinary management is important for a correct management.

A single-center experience with pancreatic cystic neuroendocrine tumors

BACKGROUND

Pancreatic neuroendocrine tumors (PNET) are rare, with a significant malignant potential. This study aimed to determine outcomes of patients with resected PNETs according to the cystic component and confirm the accuracy of preoperative staging.

METHODS

From 1997 to 2016, 106 patients underwent resection of PNETs, including 73 purely solid (S-PNETs, 69%), 21 mixed (M-PNETs, 20%), and 12 purely cystic lesions (C-PNETs, 11%). To ensure consistent comparisons of overall (OS) and disease-free (DFS) survival outcomes between the 3 groups, the patients were matched according to the World Health Organization (WHO) grade and tumor height.

RESULTS

Overall, the rate of correlation between the preoperative and pathological diagnoses was low in the C-PNET group (33%, P = 0.03). None of the 24 patients (23%) with metastatic disease at the time of surgery were in the C-PNET group. Furthermore, significantly more parenchyma-sparing resections (P = 0.039) and fewer enlarged resections (P = 0.019) were achieved in the C-PNET group. C-PNET group had a significantly lower node invasion rate than the S-PNET and M-PNET groups (8% vs. 41% and 24%, P = 0.004). Although median OS was comparable in all 3 groups before (P = 0.3) and after (P = 0.18) matching, higher median DFS was observed in the C-PNET group than in the other groups after matching (P = 0.038).

CONCLUSION

C-PNET was associated with a better prognosis than PNET with a solid component. The results support a wait-and-see policy in cases wherein a reliable preoperative diagnosis remains challenging.

Nondegenerated cystic neuroendocrine tumor of the pancreas: a case report

Background

Pancreatic neuroendocrine tumors (PNETs) are typically solid neoplasms but, in very rare cases, present as cystic lesions. We describe a case of a cystic neuroendocrine tumor that developed as a small cystic lesion.

Case presentation

In 2011, a 66-year-old Japanese woman underwent computed tomography (CT) that revealed a cystic lesion in the tail of the pancreas measuring 9 mm. She did not have any symptoms. She underwent a CT scan every year thereafter. The cystic lesion gradually increased and was 40 mm in 2019; endoscopic retrograde pancreatography (ERP) was then performed. Cytological examination demonstrated class IIIb adenocarcinoma, and we conducted laparoscopic distal pancreatectomy. Pathological examination showed PNET.

Conclusion

Although cystic change of PNET is generally caused by ischemia or necrosis inside the tumor, in our case, PNET occurred as a small cyst that increased without changing form.

Interesting pancreatic tumour in the background of Tuberous Sclerosis

Tuberous Sclerosis Complex (TSC) is easily discernible by a myriad of manifestations, most notably dermatological. It is associated with well known and recognised intra-abdominal tumours like angiomyolipoma of the kidney. However, rarer tumours like pancreatic neuroendocrine tumours can occur in the setting of TSC. A high index of suspicion is necessary to identify and treat these lesions early in their natural course. Early identification augurs well with complete surgical excision and excellent survival.

Cystic pancreatic neuroendocrine tumors: A distinctive subgroup with indolent biological behavior? A systematic review and meta-analysis

BACKGROUND/OBJECTIVES

The clinicopathological features and biological behaviors of cystic pancreatic neuroendocrine tumors (pNETs) are unclear and controversial. Here we performed a systematic review and meta-analysis to investigate the unique characteristics of cystic pNETs, to determine whether they represent a distinct clinical entity.

METHODS

We selected comparative studies published since January 2000 that explore the differences between clinicopathological features of cystic and solid pNETs. Demographic information, pathological characteristics, and survival information were analyzed.

RESULT

The 12 selected studies comprised 355 and 1530 patients diagnosed with cystic and solid pNETs, respectively. Compared with solid pNETs, cystic pNETs were less likely to be functional (odds ratio, OR = 0.31, 95% confidence interval (CI) 0.19-0.50, p < 0.00001), more likely to affect males (OR = 1.56, 95% CI 1.22-2.00, p = 0.0005), and significantly associated with multiple endocrine neoplasia type 1 (OR = 2.71). Cystic pNETs were more likely to present with G1 and G2 rather than G3 (OR = 1.66). Cystic pNETs were associated with less frequent distant organs and lymph node metastasis, microvascular invasion, perineural invasion, and a low Ki-67 index and mitotic count. There were no significant differences between 5- and 10-year overall survival. However, the 5-year disease-free survival (DFS) and 10-year DFS rate of patients with cystic pNETs was significantly higher compared with those with solid pNETs (94.6% vs 83.5%, OR = 3.00; 92.7% vs 63.6%, OR = 5.92, respectively).

CONCLUSIONS

Cystic pNETs represent a distinct subgroup of pNETs that present with an indolent biological behavior, and patients experience better DFS. Observation and surveillance should be considered in some selected cases.

Cystic pancreatic neuroendocrine tumors: A more favorable lesion?

BACKGROUND

Pancreatic neuroendocrine tumors (PNETs) are predominantly solid lesions with malignant potential. Cystic PNETs are a small subset in which data are scarce. The aim of this study was to compare clinical and biologic differences between cystic and solid PNETs.

METHODS

Patients with PNETs undergoing pancreatectomy between 1988 and 2016 at a high-volume center were reviewed retrospectively. Demographic, clinical, and histopathologic data were collected and analyzed.

RESULTS

347 patients with PNETs were identified; 27% (n = 91) were cystic. Patients with cystic PNETs were generally older (59 vs. 55 years, p = 0.05). Cystic PNETs were more commonly non-functional (95% vs. 82%, p = 0.004), asymptomatic (44% vs. 28%, p = 0.009), and located in the pancreatic body/tail (81% vs. 60%, p < 0.001) than solid PNETs. Although cystic and solid PNETs had similar sizes and pathologic stage at the time of resection, Ki-67 proliferation index (Ki-67 ≤ 9%: 98% vs. 85%; p = 0.007), and histologic grade (grade I: 84% vs. 59%; p = 0.009) had less aggressive features in cystic PNETs.

CONCLUSION

In addition to reporting a higher than previously published incidence of cystic PNET (27%), this study found significant differences in multiple clinicopathologic variables between cystic and solid PNETs. Cystic PNET may be a distinct and possibly less aggressive subtype of PNET yet have similar pathologic stage, recurrence, and survival to solid PNETs. Cystic PNETs require further attention to better understand the true natural history.

Pancreatic Cystic Lesions: Pathogenesis and Malignant Potential

Pancreatic cancer remains one of the most lethal cancers despite extensive research. Further understanding of precursor lesions may enhance the ability to treat and prevent pancreatic cancer. Pancreatic cystic lesions (PCLs) with malignant potential include: mucinous PCLs (intraductal papillary mucinous neoplasms and mucinous cystic neoplasm), solid pseudopapillary tumors and cystic neuroendocrine tumors. This review summarizes the latest literature describing what is known about the pathogenesis and malignant potential of these PCLs, including unique epidemiological, radiological, histological, genetic and molecular characteristics.

Clinical impact of endoscopic ultrasonography on the management of neuroendocrine tumors: lights and shadows

The incidence of gastroenteropancreatic neuroendocrine neoplasms has increased in the recent decades. An extensive bibliographical search was performed in PubMed to identify guidelines and primary literature (retrospective and prospective studies, systematic reviews, case series) published mostly between year 1997 and June 2017, using both medical subject heading (MeSH) terms and free-language keywords about the accuracy and diagnostic and therapeutic role of endoscopic ultrasound in the context of gastro-entero-pancreatic neuroendocrine neoplasms. Endoscopic ultrasound is the modality of choice for diagnosing pancreatic neuroendocrine neoplasms and for the locoregional staging of gastric, duodenal, pancreatic and rectal neuroendocrine neoplasms; in particular, in the setting of pancreatic neuroendocrine neoplasms it has demonstrated higher accuracy in tumor detection than other imaging modalities. Furthermore, the possibility of tattooing pancreatic lesions by endoscopic ultrasound fine needle aspiration may help surgeons to locate the tumor and avoid any demolition surgery. Finally, endoscopic ultrasound-guided therapies have been proposed and used in several studies for patients unsuitable for surgery, with good results on the control of symptoms and the reduction of tumor burden.

Neuroendocrine tumors of the pancreas: Degree of cystic component predicts prognosis

BACKGROUND

Although most pancreatic neuroendocrine tumors are solid, approximately 10% are cystic. Some studies have suggested that cystic pancreatic neuroendocrine tumors are associated with a more favorable prognosis.

METHODS

A retrospective review of all patients with pancreatic neuroendocrine tumors who underwent operative resection between 1999 and 2014 at a single academic medical center was performed. Based on cross-sectional imaging performed before operation, pancreatic neuroendocrine tumors were classified according to the size of the cystic component relative to the total tumor size: purely cystic (100%), mostly cystic (≥50%), mostly solid (<50%), and purely solid (0%). Clinicopathologic characteristics and recurrence-free survival were assessed between groups.

RESULTS

In the study, 214 patients met inclusion criteria: 8 with purely cystic tumors, 7 with mostly cystic tumors, 15 with mostly solid tumors, and 184 with purely solid tumors. The groups differed in terms of tumor size (1.5 ± 0.5, 3.0 ± 1.7, 3.7 ± 2.6, and 4.0 ± 3.5 cm), lymph node positivity (0%, 0%, 26.7%, and 34.2%), intermediate or high grade (0%, 16.7%, 20.0%, and 31.0%), synchronous liver metastases (0%, 14.3%, 20.0%, and 26.6%) and need for pancreaticoduodenectomy (0%, 0%, 6.7%, and 25.0%), respectively. No cases of purely cystic pancreatic neuroendocrine tumors were associated with synchronous liver or lymph node metastasis, intermediate/high grade, recurrence, or death due to disease. Among patients presenting without metastatic disease, 10-year recurrence-free survival was 100% in patients with purely and mostly cystic tumors versus 53.0% in patients with purely and mostly solid tumors; however, this difference did not reach statistical significance.

CONCLUSION

Pancreatic neuroendocrine tumors demonstrate a spectrum of biologic behavior with an increasing cystic component being associated with more favorable clinicopathologic features and prognosis. Purely cystic pancreatic neuroendocrine tumors may represent 1 subset that can be safely observed without immediate resection.

Endoscopic ultrasound-guided fine-needle aspiration for the diagnosis of pancreatic cysts by combined cytopathology and cystic content analysis

Recent advances in imaging technology have resulted in an increase in incidental discoveries of pancreatic cystic lesions. Pancreatic cysts comprise a wide variety of lesions and include non-neoplastic cysts and neoplastic cysts. Because some pancreatic cysts have more of a malignant potential than others, it is absolutely essential that an accurate diagnosis is rendered so that effective care can be given to each patient. In many centers, endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) has emerged as the modality of choice that enables one to distinguish between mucinous and non-mucinous lesion, diagnose malignancy and collect cyst fluid for further diagnostic studies, such as pancreatic enzyme levels, molecular analysis and other tumor biomarkers. The current review will focus on EUS-guided FNA and the cytological diagnosis for pancreatic cysts.