Clinico-pathological features of cystic pancreatic endocrine neoplasms and a comparison with their solid counterparts

Role of contrast-enhanced ultrasound with time-intensity curve analysis for differentiating hypovascular solid pancreatic lesions

OBJECTIVES

To evaluate the clinical value of contrast-enhanced ultrasound (CEUS) with time-intensity curve (TIC) in distinguishing different types of hypovascular solid pancreatic lesions.

METHODS

A total of 89 patients with 90 pancreatic lesions (all confirmed by surgery or biopsy pathology) that manifested hypoenhancement on contrast-enhanced ultrasound (CEUS) were included in this study. Six peak enhancement patterns were proposed for differentiating hypovascular pancreatic lesions. CEUS qualitative and TIC-based quantitative parameters were analyzed, and each lesion was scored based on the statistically significant qualitative parameters to evaluate the diagnostic ability of CEUS for hypovascular solid pancreatic lesions.

RESULTS

Qualitative parameters such as peak enhancement pattern II/III/IV, penetrating vessels, centripetal enhancement, and early washout were reliable indicators of malignant lesions, and lesions scored based on these qualitative parameters, with a score ≥ 2, were highly suspected to be malignant lesions. Pattern I had an accuracy of 83.33% for predicting mass-forming pancreatitis (MFP), pattern V had an accuracy of 96.67% for predicting solid pseudopapillary tumors of the pancreas (SPTP), and pattern VI had an accuracy of 81.11% for predicting neuroendocrine tumors/carcinomas (NETs/NECs). For quantitative analysis, nodule/pancreatic parenchyma echo intensity reduction ratio was significantly greater in malignant lesions.

CONCLUSIONS

CEUS qualitative and TIC-based quantitative parameters have clinical value in distinguishing malignant from benign hypovascular pancreatic lesions.

KEY POINTS

• Contrast-enhanced ultrasound helps clinicians assess patients with pancreatic lesions. • Six peak enhancement patterns are proposed for differentiating pancreatic hypovascular lesions. • Qualitative parameters such as peak enhancement pattern II/III/IV, penetrating vessels, centripetal enhancement, early washout, and quantitative parameter nodule/pancreatic parenchyma echo intensity reduction ratio were important characteristics to discriminate malignant from hypovascular benign lesions.

Integrating Molecular Analysis into the Pathologic Evaluation of Pancreatic Cysts

The development of cross-sectional imaging techniques has enhanced the detection of pancreatic cystic lesions (PCLs). PCLs are found in approximately 2% of the general population, often as incidentally detected lesions on computed tomography or MRI during the evaluation of other medical conditions. Broadly, PCLs are classified as mucinous or nonmucinous. Mucinous PCLs include mucinous cystic neoplasms and intraductal papillary mucinous neoplasms. Nonmucinous PCLs include pseudocysts, serous cystadenomas, solid pseudopapillary neoplasms, and cystic pancreatic neuroendocrine tumors, as well as cystic acinar cell carcinoma, cystic degeneration of pancreatic ductal adenocarcinoma, lymphoepithelial cyst, and others.

Pancreatic Cystic Neoplasms

Early detection of high-risk pancreatic cystic lesions enables potentially curative surgical resection, and early detection of lesions without worrisome features may lead to appropriate surveillance. Regrettably, differentiating premalignant and malignant cysts from nonmalignant ones remains challenging. However, emerging additional diagnostic tools, including the needle biopsy with microforceps and needle-based confocal laser endomicroscopy, are of exciting potential along with cyst fluid analysis".

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.

Reappraisal of a 2-Cm Cut-off Size for the Management of Cystic Pancreatic Neuroendocrine Neoplasms: A Multicenter International Study

OBJECTIVE

The aim of this study was to characterize an international cohort of resected cystic pancreatic neuroendocrine neoplasms (cPanNENs) and identify preoperative predictors of aggressive behavior.

BACKGROUND

The characteristics of cPanNENs are unknown and their clinical management remains unclear. An observational strategy for asymptomatic cPanNENs ≤2 cm has been proposed by recent guidelines, but evidence is scarce and limited to single-institutional series.

METHODS

Resected cPanNENs (1995-2017) from 16 institutions worldwide were included. Solid lesions (>50% solid component), functional tumors, and MEN-1 patients were excluded. Aggressiveness was defined as lymph node (LN) involvement, G3 grading, distant metastases, and/or recurrence.

RESULTS

Overall, 263 resected cPanNENs were included, among which 177 (63.5%) were >2 cm preoperatively. A preoperative diagnosis of cPanNEN was established in 162 cases (61.6%) and was more frequent when patients underwent endoscopic ultrasound [EUS, odds ratio (OR) 2.69, 95% confidence interval (CI) 1.52-4.77] and somatostatin-receptor imaging (OR 3.681, 95% CI 1.809-7.490), and for those managed in specialized institutions (OR 3.12, 95% CI 1.57-6.21). Forty-one cPanNENs (15.6%) were considered aggressive. In the whole cohort, LN involvement on imaging, age >65 years, preoperative size >2 cm, and pancreatic duct dilation were independently associated with aggressive behavior. In asymptomatic patients, older age and a preoperative size >2 cm remained independently associated with aggressiveness. Only 1 of 61 asymptomatic cPanNENs ≤2 cm displayed an aggressive behavior.

CONCLUSIONS

The diagnostic accuracy of cPanNENs is increased by the use of EUS and somatostatin-receptor imaging and is higher in specialized institutions. Preoperative size >2 cm is independently associated with aggressive behavior. Consequently, a watch-and-wait policy for sporadic asymptomatic cPanNENs ≤2 cm seems justified and safe for most patients.

The distinctive characteristics of the micro-vasculature and immune cell infiltration in cystic pancreatic neuroendocrine tumors

PURPOSE

Hypervascularity is a main characteristic of pancreatic neuroendocrine tumors (PanNETs), and cystic PanNETs (CPanNETs) are unique type of PanNETs in which the microenvironment remains unknown. We aim to compare the micro-vasculature features and immune cell infiltration between CPanNETs and solid PanNETs (SPanNETs).

METHODS

Data of 301 SPanNET and 36 CPanNET patients from a high-volume institution were evaluated. CD4, CD8, CD11c, CD15, CD20, CD68, CD34 and α-SMA expression levels were assessed by immunohistochemistry and immunofluorescent double staining. The microvessel density (MVD) and microvessel integrity (MVI) were examined.

RESULTS

MVD and MVI expression levels in CPanNETs were significantly higher than those in SPanNETs (p = 0.025 and 0.0092, respectively). CPanNETs had higher proportions of T1 (p = 0.023) and G1 (p = 0.052) than SPanNETs. In SPanNETs, higher MVD occurred in stages T1, N0 and G1 than in the T2/T3, N1 and G2 subgroups. In CPanNETs, CD34-MVD was uncorrelated with the T stage or grade. Higher CD34-MVD, but not MVI, was associated with better DFS (HR 0.3209, 95% CI 0.1259-0.8176, p = 0.004). There were significantly more peritumoral infiltrating immune cells than their intratumoral counterparts (p < 0.001 for each) in CPanNETs and SPanNETs. The mean number of peritumoral CD68 + TAM in CPanNETs was significantly lower than that in SPanNETs (p = 0.008). The counts of other peritumoral immune cells did not significantly differ between CPanNETs and SPanNETs.

CONCLUSIONS

CPanNETs had a microenvironment distinct from that of SPanNETs, including higher CD34-MVD, higher MVI and lower TAM. This specific microenvironment structure may partially help predicting the prognosis of patients with PanNET.

Cystic Pancreatic Neuroendocrine Tumors Represent a Distinct Clinical Entity with Less Aggressive Biological Behaviors

BACKGROUND

Pancreatic neuroendocrine tumors (pNETs) uncommonly present as cystic lesions. There is a gap in knowledge of their clinicopathological characteristics and biological behaviors. Previous reported studies remained inconsistent and controversial. The purpose of this study is to investigate the clinicopathological features of cystic pNET and determine if it represents a distinct clinical entity by comparing its characteristics with those of solid pNETs.

METHODS

Patients with pNETs who underwent surgical resections from January 2014 to April 2019 at Qilu Hospital of Shandong University were reviewed retrospectively. Demographics, clinical characteristics, surgical data, and oncological as well as histological characteristics of cystic pNETs and their solid counterparts were collected and analyzed.

RESULTS

A total of 122 patients were included in this study, and 10.7% (13/122) patients were cystic. There is no significant difference between cystic pNETs and solid pNETs in age (43.6 ± 15.8 versus 50.9 ± 14.5 y, P = 0.093) and sex distribution (P = 0.085). Cystic pNETs are more likely to be asymptomatic (61.5% versus 23.9%, P = 0.008) and nonfunctional (92.3% versus 52.7%, P = 0.006) than solid pNETs. However, the tumor size (4.8 ± 4.5 versus 2.8 ± 1.9 cm, P = 0.124), proportion of multiple endocrine neoplasia type 1 (92.3% versus 98.2%, P = 0.289), and tumor location (P = 0.154) are similar in both groups. Compared with solid pNETs, cystic pNETs have a lower Ki-67 index and incidence of liver metastasis, but the difference is not significant.

CONCLUSIONS

Cystic pNETs are more likely to be nonfunctional and indolent and seem to exhibit less aggressive biological behaviors than solid pNETs. Conservative approach should be considered for certain selected patients.

Pearls and pitfalls of imaging features of pancreatic cystic lesions: a case-based approach with imaging-pathologic correlation

A variety of neoplastic and non-neoplastic lesions of the pancreas can present with a predominantly cystic architecture. These lesions are increasingly being detected as incidental findings on routine cross-sectional imaging following technological advances in these techniques and their widespread use. The different histopathological behaviors show various common and uncommon imaging findings, and some cases show similar appearance in spite of different histopathology. Each lesion requires specific management because of the differing risk of progression to malignancy, and an accurate imaging diagnosis is crucial. The typical imaging characteristics that differentiate pancreatic cystic lesions have been well described and fully summarized. However, in addition to a small percentage of cases that shows uncommon imaging findings, a substantial percentage of cystic lesions shows overlapping imaging findings that can lead to radiological misdiagnosis. For appropriate diagnosis and optimal treatment strategy, it is important to know the uncommon and overlapping imaging findings of these lesions, in addition to familiarity with the typical aspects. In this article, we reconfirm the well-known characteristic imaging features of pancreatic cystic lesions and present several diagnostically challenging cases, focusing on the uncommon and overlapping imaging findings.

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.

The rare case of a cystic pancreatic neuroendocrine tumor

The pancreatic neuroendocrine tumors (PanNETs) most commonly present as solid neoplasms; however, very rarely, they may present primarily as cystic neoplasms. Most of the cystic PanNETs are non-secreting tumors, and the radiological features are not well defined. Hence pre-operative diagnosis is usually challenging and the tumors are misdiagnosed as mucinous cystic neoplasms, intraductal papillary mucinous neoplasms, serous cystic neoplasms, solid pseudopapillary neoplasms, and non-neoplastic cysts. However, the management depends on the accurate diagnosis of these cystic lesions, which poses a dilemma. Herein, we report the case of a cystic PanNET in the tail of the pancreas, which was clinically and radiologically misdiagnosed as a mucinous cystic neoplasm. This case is reported to highlight this issue to the medical community regarding the diagnostic difficulty in such rare non-functioning pancreatic neuroendocrine tumors.

Cystic Lesions of the Pancreas: Differential Diagnosis and Cytologic-Histologic Correlation

CONTEXT.—

Pancreatic cystic lesions (PCLs) are very common, and their detection is increasing with the advances in imaging techniques. Because of the major implications for management, distinguishing between neoplastic and nonneoplastic PCLs is critical. Neoplastic cysts with potential to progress into cancer include mucinous PCLs (intraductal papillary mucinous neoplasms and mucinous cystic neoplasms) and nonmucinous cysts (solid pseudopapillary tumors, serous cystic neoplasms, and neuroendocrine tumors with cystic degeneration). Nonneoplastic cysts with no risk of malignant transformation include pseudocysts, retention cysts, lymphoepithelial cysts, cystic pancreatic lymphangioma, and duplication cyst/ciliated foregut cysts. The role of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) cytology with cyst fluid analysis in the diagnosis of PCLs has evolved during the last decade; however, a definitive diagnosis on cytologic specimens is hampered by the sparse cellularity and can be challenging. EUS-FNA can play an important role to differentiate low-risk from high-risk pancreatic cysts and to distinguish between patients with cysts who need clinical follow-up versus those who require surgery.

OBJECTIVE.—

To provide an integrative approach to diagnose pancreatic cystic lesions using EUS-FNA cytology and cyst fluid analysis, along with clinical, radiologic, histologic, genetic, and molecular characteristics.

DATA SOURCES.—

The review and analysis of the latest literature describing pancreatic cystic lesions.

CONCLUSIONS.—

Accurate diagnosis of PCLs requires a multidisciplinary and multimodal team approach, including the integration of clinical findings, imaging, cytology, cyst fluid analysis, and molecular testing.

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.

The Impact of Repeating Endosonography with Confocal Endomicroscopy for the Diagnosis of Cystic Neuroendocrine Tumor

Cystic pancreatic neuroendocrine tumors represent around 13% of all neuroendocrine tumors (Hurtado-Pardo 2017). There has been an increase in the incidence of cases due to improvement in imaging modalities. This is a case of a 68-year-old male with the incidental finding of a pancreatic cyst on CT. Initial Endoscopic Ultrasound with Fine Needle Aspiration (EUS-FNA) showed sonographic and cytology features suggestive of a pancreatic pseudocyst. However the cyst persisted with no change in size after aspiration leading to a follow-up EUS- FNA, which was combined with needle based confocal laser endomicroscopy (nCLE). The nCLE features were consistent with a cystic pancreatic neuroendocrine tumor, which was later confirmed on histology after surgical resection.

Clinicopathological characteristics of non-functioning cystic pancreatic neuroendocrine tumors

BACKGROUND/OBJECTIVES

The biological features of cystic pancreatic neuroendocrine tumors (PNETs) remain unclear. The aim of this study was to clarify the clinicopathological characteristics of non-functioning PNETs (NF-PNETs) with a cystic component.

METHODS

The medical records of 75 patients with NF-PNETs who had undergone resection in our institution were retrospectively reviewed. Clinicopathological factors were compared between PNETs with and without a cystic component. Expression of somatostatin 2 receptor (SSTR-2) was also analyzed.

RESULTS

Cystic PNETs were diagnosed in 14 patients (19%). The proportion of men was significantly higher for cystic than solid PNETs (79% vs. 44%, P < 0.05) and cystic PNETs were significantly larger than solid PNETs (25 mm vs. 17 mm, P < 0.01). However, there were no significant differences in the prevalence of lymph node metastases (14% vs. 10%, P = 0.64), hepatic metastasis (7% vs. 3%, P = 0.54), or disease-free survival rate (both 86%, P = 0.29) between PNETs with and without a cystic component. SSTR-2 expression was more frequently observed in PNETs with a cystic component than in those without (100% vs. 70%, P < 0.01).

CONCLUSIONS

Although cystic PNETs were larger upon diagnosis than solid PNETs in this study, prognosis after surgical resection did not differ significantly between these types of PNET. Somatostatin receptor scintigraphy and somatostatin analogues may be more useful for diagnosing and treating cystic PNETs, respectively.

Cystic pancreatic neuroendocrine tumors (cPNETs): a systematic review and meta-analysis of case series

Cystic pancreatic neuroendocrine tumors represent 13% of all neuroendocrine tumors. The aim of this study is to analyze the phenotype and biologic behavior of resected cystic neuroendocrine tumors. A systematic review and meta-analysis were conducted until September 2016 using a search in Medline, Scopus, and EMBASE with the terms "cystic pancreatic endocrine neoplasm", "cystic islets tumors" and "cystic islets neoplasms". From the 795 citations recovered 80 studies reporting on 431 patients were selected. 87.1% (n = 387) were sporadic tumors and 10.3% (n = 40) corresponded to multiple endocrine neoplasia endocrine type 1. Were diagnosed incidentally 44.6% (n = 135). Cytology was found to have a sensitivity of 78.5%. Were non-functional tumors 85% (n = 338), and among the functional tumors, insulinoma was the most frequent. According to the European Neuroendocrine Tumor Society staging, 87.8% were limited to the pancreas (I-IIb), and 12.2% were advanced (III-IV). Disease-free survival at 5 years in stages (I-IIIa) and (IIIb-IV) was 91.5% and 54.2%, respectively; and was significantly lower (p = 0.0001) in functional tumors. In patients with multiple endocrine neoplasia there was a higher incidence of functional (62.5%) and multifocal (28.1%) tumors. Disease-free survival at 5 and 10 years was 60%. Cystic pancreatic neuroendocrine tumors exhibit phenotypical characteristics which are different to those of solid neuroendocrine tumors.

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.

A case of pancreatic neuroendocrine tumor with multiple cystic components of various sizes

The patient was a 51-year-old woman who, while undergoing a thorough health checkup, was found to have a tumor (measuring 60 mm in diameter) in the tail of the pancreas by abdominal ultrasonography. Contrast-enhanced computed tomography revealed delayed contrast enhancement; the tumor also contained numerous low-absorption areas showing poor contrast enhancement. On magnetic resonance imaging, the tumor was visualized as having high signal intensity areas inside the tumor on T2-weighted images. Positron emission tomography revealed an abnormal accumulation in the area corresponding to the tumor. Endoscopic ultrasonography (EUS) revealed a relatively hyperechoic solid area, with a number of echo-free areas of various sizes that assumed a honeycomb appearance. EUS-guided fine needle aspiration was carried out targeting the solid area within the tumor, which led to a diagnosis of pancreatic neuroendocrine tumor (PNET). Histopathological examination of the resected specimen revealed that the tumor was composed of numerous cysts of various sizes and solid components. The cysts contained no evidence of necrosis or bleeding. Immunohistochemically, the cystic as well as solid components were CD56 (+), synaptophysin (+) and chromogranin A (+) with MIB1 labeling index of 5%. On the basis of these findings, the final diagnosis was PNET (G2).

Rupture of small cystic pancreatic neuroendocrine tumor with many microtumors

Pancreatic neuroendocrine tumors (pNETs) are particularly rare. The various forms of PNETs, such as cystic degeneration, make differentiation from other similar pancreatic lesions difficult. We can detect small lesions by endoscopic ultrasound (EUS) and obtain preoperative pathological diagnosis by EUS-guided fine needle aspiration (FNA). We describe, here, an interesting case of pNET in a 42-year-old woman with no family history. Computed tomography and magnetic resonance imaging revealed an 18 mm × 17 mm cystic lesion with a nodule in the pancreatic tail. Two microtumors about 7 mm in diameter in the pancreatic body detected only by EUS, cystic rim and nodules all showed similar enhancement on contrast-harmonic EUS. Preoperative EUS-FNA of the microtumor was performed, diagnosing multiple pNETs. Macroscopic examination of the resected pancreatic body and tail showed that the cystic lesion had morphologically changed to a 13-mm main nodule, and 11 new microtumors (diameter 1-3 mm). Microscopically, all microtumors represented pNETs. From the findings of a broken peripheral rim on the main lesion with fibrosis, rupture of the cystic pNET was suspected. Postoperatively, pituitary adenoma and parathyroid adenoma were detected. The final diagnosis was multiple grade 1 pNETs with multiple endocrine neoplasia type 1. To the best of our knowledge, no case of spontaneous rupture of a cystic pNET has previously been reported in the English literature. Therefore, this case of very rare pNET with various morphological changes is reported.

Pancreatic Cysts and Guidelines

Pancreatic cysts, especially incidental asymptomatic ones seen on noninvasive imaging such as CT or MR imaging, remain a clinical challenge. The etiology of such cysts may range from benign cysts without any malignant potential such as pancreatic pseudocysts and serous cystadenomas to premalignant or frankly malignant cysts such as mucinous cystic neoplasms, intraductal papillary mucinous neoplasms, cystic degeneration associated with solid tumors such as pancreatic ductal adenocarcinoma or pancreatic endocrine neoplasms, and solid pseudopapillary neoplasms. The clinical challenge in 2017 is to accurately preoperatively diagnose them and their malignant potential before deciding about surgery, surveillance or doing nothing. This review will focus on the currently available clinical guidelines for doing so.

Laparoscopic splenopancreatectomy for an endocrine tumor with cystic changes: a case report

The biological behavior of a cystic pancreatic endocrine neoplasm is less aggressive than that of pancreatic neuroendocrine neoplasms, and its prognosis is better. Limited surgery should be considered for cystic pancreatic endocrine neoplasms that are not accompanied preoperatively by lymph node or distant metastasis.

Prevalence, Diagnosis and Management of Pancreatic Cystic Neoplasms: Current Status and Future Directions

Cystic neoplasms of the pancreas are found with increasing prevalence, especially in elderly asymptomatic individuals. Although the overall risk of malignancy is very low, the presence of these pancreatic cysts is associated with a large degree of anxiety and further medical investigation due to concerns about malignancy. This review discusses the different cystic neoplasms of the pancreas and reports diagnostic strategies based on clinical features and imaging data. Surgical and nonsurgical management of the most common cystic neoplasms, based on the recently revised Sendai guidelines, is also discussed, with special reference to intraductal papillary mucinous neoplasm (IPMN; particularly the branch duct variant), which is the lesion most frequently identified incidentally. IPMN pathology, its risk for development into pancreatic ductal adenocarcinoma, the pros and cons of current guidelines for management, and the potential role of endoscopic ultrasound in determining cancer risk are discussed. Finally, surgical treatment, strategies for surveillance of pancreatic cysts, and possible future directions are discussed.

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.

A Single Centre Analysis of Clinical Characteristics and Treatment of Endocrine Pancreatic Tumours

Background. Endocrine Pancreatic Tumours (PENs) are rare and can be nonfunctioning or functioning. They carry a good prognosis overall though high grade lesions show a relatively shorter survival. The aim of the current study is to describe a single centre analysis of the clinical characteristics and surgical treatment of PENs. Patients and Methods. This is a cohort analysis of 40 patients of PENs who underwent surgery at Sir Ganga Ram Hospital, New Delhi, India, from 1995 to 2013. Patient particulars, clinical features, surgical interventions, postoperative outcome, and followup were done and reviewed. The study group was divided based on grade (G1, G2, and G3) and functionality (nonfunctioning versus functioning) for comparison. Results. PENs comprised 6.3% of all pancreatic neoplasms (40 of 634). Twenty-eight patients (70%) had nonfunctioning tumours. Eighteen PENs (45%) were carcinomas (G3), all of which were nonfunctioning. 14 (78%) of these were located in the pancreatic head and uncinate process (P = 0.09). The high grade (G3) lesions were significantly larger in size than the lower grade (G1 + G2) tumours (7.0 ± 3.5 cms versus 3.1 ± 1.6 cms, P = 0.007). Pancreatoduodenectomy was performed in 18 (45%), distal pancreatectomy in 10 (25%), and local resection in 8 (20%) and nonresective procedures were performed in 4 patients (10%). Fourteen patients (35%) had postoperative complications. All G3 grade tumours which were resected had positive lymph nodes (100%) and 10 had angioinvasion (71%). Eight neoplasms (20%) were cystic, all being grade G3 carcinomas, while the rest were solid. The overall disease related mortality attributable to PEN was 14.3% (4 of 28) and for malignant PENs was 33.3% (4 of 12) after a mean follow-up period of 49.6 months (range: 2–137 months). Conclusion. Majority of PENs are nonfunctioning. They are more likely malignant if they are nonfunctioning and large in size, show cystic appearance, and are situated in the pancreatic head. Early surgery leads to good long term survival with acceptable postoperative morbidity.

Endoscopic ultrasonography-guided fine-needle aspiration cytology of surgically confirmed cystic pancreatic neuroendocrine tumors: a Mayo Clinic experience

INTRODUCTION

Endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA) cytology is widely used to evaluate solid and cystic pancreatic lesions preoperatively. Pancreatic neuroendocrine tumors (PanNETs) are typically solid, but when they are cystic, differentiation from other pancreatic cystic neoplasms can be challenging. We examined cases of cystic PanNETs (cPanNETs) from 3 Mayo Clinic Hospitals focusing on the EUS-FNA cytology.

MATERIALS AND METHODS

A total of 21 EUS-FNA cases of cPanNETs with histology confirmation were identified from the Mayo Clinic Health System database. The patients' demographic data, clinical, radiological, and EUS characteristics were obtained. EUS-FNA cytology and surgical pathology were reviewed.

RESULTS

Among the 21 patients with cPanNETs, only 2 of 21 cases had suggestion of cPanNET on preoperative imaging (computed tomography/magnetic resonance imaging). On EUS, most cPanNETs (16/ of 21) had ≥1 high-risk stigmata or worrisome feature per the Sendai Consensus guidelines. None of the cases had an elevated carcinoembryonic antigen level. EUS-FNA cytology was positive or suspicious for cPanNET in 15 of 21 cases (71.4%). Immunohistochemical stains of neuroendocrine markers were performed on all the positive or suspicious cases and showed positivity for ≥1 neuroendocrine marker. All cases had surgical resection and the diagnosis of cPanNET was confirmed on each case.

CONCLUSIONS

Although computed tomography/magnetic resonance imaging has a low specificity for detecting cPanNETs, high-risk features on EUS and low carcinoembryonic antigen levels should raise the suspicion for cPanNET. EUS-FNA cytology along with immunohistochemical stains has a high accuracy in establishing the preoperative diagnosis of cPanNET.

Pancreatic Neuroendocrine Neoplasms

Pancreatic neuroendocrine neoplasms (Pan-NENs) are rare but clinically important lesions. Pan-NENs are known for and often categorized by their capacity to produce clinical syndromes mediated by the production of hormones. Despite sometimes presenting dramatically from excessive hormone production, not all Pan-NENs produce functional hormone, and they can pose diagnostic challenges to practicing pathologists. Distinguishing Pan-NENs from mimics can be crucial, because Pan-NENs carry different prognoses and have unique treatments available due to their specific biological properties. This article reviews the current categorization and features of Pan-NENs.

Endoscopic diagnosis and treatment of pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (PNETs) are rare pancreatic neoplasms comprising only 1% to 2% of all pancreatic tumors. In recent years, the number of incidentally discovered PNETs has greatly increased given the widespread use of axial imaging. However, a significant proportion of PNETs may not be visualized on conventional imaging such as computed tomography, magnetic resonance imaging, and somatostatin receptor scintigraphy. Endoscopic ultrasound (EUS) has become an integral part of the diagnosis of PNETs because of its high sensitivity for detecting, localizing, and diagnosing PNETs. EUS-guided tissue acquisition provides histologic and immunologic confirmation, and may also allow prognostication about tumor behavior. In addition to preoperative assessment of these tumors, EUS has also been shown to have an important role in nonoperative management of small nonfunctional PNETs. Finally, recent developments suggest that interventional EUS may be used to aid intraoperative localization of PNETs and to deliver therapeutic agents for the treatment of PNETs. This review will discuss the endoscopic diagnosis and treatment of PNETs, with focus on recent advances in the utility of EUS in the clinical management of these tumors.

A systematic review and meta-analysis of the clinicopathologic characteristics of cystic versus solid pancreatic neuroendocrine neoplasms

INTRODUCTION

Cystic pancreatic neuroendocrine neoplasms (PNENs) are rare neoplasms, and presently, it is uncertain whether their behavior is similar or distinct from their solid counterparts. This study aimed to review systematically the present literature to compare the clinicopathologic characteristics of cystic PNENs versus their solid counterparts to determine whether cystic PNENs are likely to be a distinct entity from solid PNENs.

METHODS

Comparative studies of solid versus cystic PNENs studies were reviewed. Cystic and solid PNENs were compared on the basis of several clinicopathologic characteristics.

RESULTS

Seven nonrandomized case control studies compared 152 cystic versus 915 solid PNENs. Pooled analysis demonstrated that the likelihood of PNENs to be located in the head/uncinate of the pancreas was lower for cystic than solid neoplasms (27.7% vs 45.5%, odds ratio [OR] 0.452, 95% confidence interval [95% CI] 0.304-0.673, P < .001). Cystic PNENs were less likely to be functional (14% vs 24.4%, OR 0.405, 95% CI 0.221-0.742, P = .003) and were more likely to be benign/uncertain rather than malignant compared with solid PNENs (90.3% vs 65.9%, OR 3.151, 95% CI 1.297-7.652, P = .011). Cystic PNENs were more likely to have a mitotic count <2 per 10 hpf and a Ki67 index <2% (93.3% vs 72.7%, OR 4.897, 95% CI 2.139-11.209, P < .001 and 82.4% vs 54.1%, OR 4.079, 95% CI 2.177-7.641, P < .001), respectively. Cystic neoplasms were also less likely to have regional lymph node metastases than solid neoplasms (11.2% vs 28.9%, OR 0.387, 95% CI 0.219-0.685, P = .001).In this meta-analysis, there was no difference in the 5-year overall survival and 5-year disease-free survival between cystic vs solid PNENs (92.0% vs 86.8%, P .214) and (98.1% vs 83.9%, P = .185).

CONCLUSION

These findings suggest that cystic PNENs tend to be biologically less aggressive compared with their solid counterparts; more data, however, with respect to molecular analysis are required to establish whether cystic and solid PNENs were distinct pathologic entities.

Cystic pancreatic neuroendocrine tumors: the value of cytology in preoperative diagnosis

BACKGROUND

Cystic pancreatic neuroendocrine tumors (cPanNETs) account for 13% to 17% of PanNETs. Although the value of endoscopic ultrasound (EUS) imaging and cyst fluid analysis (CFA) in their preoperative diagnosis has been well described, limited information is available about the diagnostic role of cytology samples obtained from fine-needle aspiration (FNA).

METHODS

Cytopathology records between 1992 and 2013 were searched for all reports of cysts interpreted as PanNET. Patient demographics, clinical and radiologic information, CFA, histopathology, and cytopathology findings were recorded. Performance characteristics of cytology and EUS for the accurate diagnosis of cPanNET were calculated.

RESULTS

In total, 35 FNAs from 33 patients with cPanNETs were identified, and 34 EUS were performed. Cytology made a specific diagnosis of a cPanNET in 71% of the biopsies compared with a specific diagnosis by EUS in 38% of cases. An interpretation of suspicious for cPanNET was given in 77% of cases by cytology and in 47% by EUS. Cytology identified 86% of the lesions as high-risk pancreatic cysts compared with 56% by EUS. Diagnostic morphology was present on both cytology and cell block preparations in 60% of aspirates, on cytology only in 20%, and on cell block only in 20%. CFA was performed on 51% cyst fluids. All cysts but 1 revealed low carcinoembryonic antigen levels (range, 0.2 to >500 ng/mL; mean, 29.5 ng/mL), and amylase levels were <500 U/L in all but 2 cases (range, 16-1493 U/L; mean, 205 U/L).

CONCLUSIONS

Cytology is the most accurate test for preoperative diagnosis of cPanNETs. EUS is insufficiently accurate for independent diagnosis, and carcinoembryonic antigen and amylase analyses are noncontributory.

Are the Sendai and Fukuoka consensus guidelines for cystic mucinous neoplasms of the pancreas useful in the initial triage of all suspected pancreatic cystic neoplasms? A single-institution experience with 317 surgically-treated patients

BACKGROUND

The Sendai Consensus Guidelines (SCG) were formulated in 2006 and updated in Fukuoka in 2012 (FCG) to guide management of cystic mucinous neoplasms of the pancreas. This study aims to evaluate the clinical utility of the SCG and FCG in the initial triage of all suspected pancreatic cystic neoplasms.

STUDY DESIGN

Overall, 317 surgically-treated patients with a suspected pancreatic cystic neoplasm were classified according to the SCG as high risk (HR(SCG)) and low risk (LR(SCG)), and according to the FCG as high risk (HR(FCG)), worrisome (W(FCG)), and low risk (LR(FCG)). Cystic lesions of the pancreas (CLP) were classified as potentially malignant/malignant or benign according to the final pathology.

RESULTS

The presence of symptoms, proximal lesions with obstructive jaundice, elevated serum carcinoembryonic antigen/carbohydrate antigen 19-9 (CEA/CA 19-9), size ≥3 cm, presence of solid component, main pancreatic duct dilatation, thickened enhancing walls, and change in ductal caliber with distal atrophy were predictive of a potentially malignant/malignant CLP on univariate analyses. The positive predictive value (PPV) and negative predictive value (NPV) of HR(SCG) and HR(ICG2012) for a potentially malignant/malignant lesion was 67 and 88 %, and 88 and 92.5 %, respectively. There were no malignant lesions in both LR groups but some potentially malignant lesions such as cystic pancreatic neuroendocrine neoplasms with uncertain behavior were classified as LR.

CONCLUSION

The updated FCG was superior to the SCG for the initial triage of all suspected pancreatic cystic neoplasms. CLP in the LR(FCG) group can be safely managed conservatively, and those in the HR(FCG) group should undergo resection.

Endosonographic and cyst fluid characteristics of cystic pancreatic neuroendocrine tumours: a multicentre case series

BACKGROUND

Pancreatic neuroendocrine tumours are uncommon neoplasms which may rarely be cystic. Differentiation from other more common cystic neoplasms may be difficult.

AIMS

To describe the morphologic, cytologic, and cyst fluid characteristics of cystic pancreatic neuroendocrine tumours.

METHODS

Retrospective analysis of consecutive patients referred for endosonographic evaluation of pancreatic cysts at four centres.

RESULTS

27 patients (12 males) with cystic pancreatic neuroendocrine tumours were identified. Prior to endosonography, this tumour was suspected in only 2 patients based on presenting symptoms (7.4%). The median cyst size was 35 mm (range 8-80 mm). Wall thickening was identified in 13 cases. The median carcinoembryonic antigen level was 1.25 (range 0.6-500). Fine needle aspiration cytology in 17 of 24 patients confirmed neuroendocrine tumour (71%). In 8 of 9 patients who had needle targeting of the cyst wall, cytology was consistent with neuroendocrine tumour (88.9%). 18 patients underwent surgical resection.

CONCLUSIONS

Cystic pancreatic neuroendocrine tumour was rarely suspected, including by cross-sectional imaging. Wall thickening was identified in approximately half of cases on endosonography. Cyst fluid was typically non-viscous with very low carcinoembryonic antigen levels. Targeting the wall during fine needle aspiration had a high diagnostic yield and should be performed.

Pancreatic neuroendocrine tumor with cystlike changes: evaluation with MDCT

OBJECTIVE

The objective of our study was to determine the prevalence and CT appearance of cystlike changes of pancreatic neuroendocrine tumor (NET), particularly of small (≤ 3 cm) tumors.

MATERIALS AND METHODS

The clinical records, images, and pathologic reports of 74 consecutive patients (average age, 55.5 years) with surgically resected pancreatic NETs who underwent preoperative CT were retrospectively reviewed. The size and location of the pancreatic NETs were recorded. The tumors were classified on the basis of CT appearance as small (≤ 3 cm) or large (> 3 cm) and as solid, partially (≤ 50% or > 50%) cystic, or purely (≈ 100%) cystic. Peripheral contrast enhancement on CT was characterized, and lymph node and liver metastases found by pathologic examination were recorded.

RESULTS

A total of 78 pancreatic NETs were reviewed. Five were not visualized on CT, leaving 73 pancreatic NETs in 69 patients (multiple tumors were visualized on CT of three patients) for analysis. The mean size of the 73 tumors was 3.0 ± 2.6 (SD) cm (range, 0.7-13.1 cm); 52 tumors were 3 cm or smaller and 21 tumors were larger than 3 cm. Gross pathologic results confirmed that 13 of the 73 (17.8%) tumors were predominantly (> 50% or ≈ 100%) cystic: 10 of the 52 (19.2%) tumors 3 cm or smaller and three of the 21 (14.3%) tumors larger than 3 cm. Peripheral contrast enhancement was seen in 11 of the 13 (85%) predominantly cystic pancreatic NETs. Compared with solid pancreatic NETs, predominantly cystic pancreatic NETs were less commonly associated with lymph node and liver metastases.

CONCLUSION

Cystic pancreatic NETs are not rare and should be included in the differential diagnosis of a cystic pancreatic mass, particularly if the cystic mass is associated with peripheral contrast enhancement. A minority of cystic pancreatic NETs can present with no peripheral enhancement.

Incidental neuroendocrine tumors of the pancreas: MDCT findings and features of malignancy

OBJECTIVE

The objective of our study was to evaluate the MDCT features of incidentally detected neuroendocrine tumors (NETs) of the pancreas, identify features that can predict tumor biology or aggressiveness and long-term outcome, and determine the incidence of "nonbenign" behavior.

MATERIALS AND METHODS

In this retrospective study, 60 histologically verified pancreatic NETs incidentally detected with contrast-enhanced MDCT were included. Various MDCT features such as size, morphology, enhancement, and presence of calcifications were evaluated and were correlated with tumor biology on histopathology. The sensitivity, specificity, predictive values, and accuracy were calculated for MDCT features in predicting nonbenign biology and risk of recurrence.

RESULTS

A total of 32 of 60 (53%) NETs were nonbenign: most were large (mean, 29.1 mm) with a solid or complex pattern. NET size of 3 cm or larger yielded a positive predictive value of 61% for nonbenign tumors and 100% when calcification was present. In 12 patients with recurrence, 92% of NETs were nonbenign. The presence of calcification, local invasion, main pancreatic duct dilatation, vascular invasion, and lymph node enlargement along with angioinvasion and a Ki-67 index greater than 2% on histology were associated with a nonbenign diagnosis and a higher risk of recurrence.

CONCLUSION

Approximately 50% of incidental NETs show uncertain or malignant behavior. Solid tumors 3 cm or larger are commonly nonbenign; however, about 30% of tumors smaller than that size cutoff can be malignant. Nonbenign tumors and those with invasive features on MDCT have a higher incidence of recurrence.

Cystic pancreatic neuroendocrine tumors: a clinicopathologic study

Pancreatic neuroendocrine tumors (PanNETs) are typically solid neoplasms but in rare instances may present as cystic lesions. This unusual presentation can make clinical diagnosis challenging. In addition, the clinical and histopathologic characteristics of cystic PanNETs are poorly defined. We identified 53 cystic PanNETs in our single-institution experience of 491 surgically resected PanNETs. Similar to solid PanNETs, cystic PanNETs developed with an equal sex distribution and over a wide age range (23 to 91 y; mean, 52 y). The unusual cystic appearance made radiologic differentiation from other cystic pancreatic neoplasms difficult with a misdiagnosis in 23 of 53 (43%) cases. An association between cystic PanNETs and multiple endocrine neoplasia type 1 or multifocal disease [5 of 53 (9%) and 7 of 53 (13%), respectively] was not observed as compared with solid PanNETs (P=0.34 and P=0.31, respectively). Grossly, cystic PanNETs were predominantly located in the tail of the pancreas (n=28, 53%) and were similar in size (mean, 3.3 cm) to solid PanNETs (mean, 4.1 cm; P=0.12). All cysts were unilocular (n=53, 100%) and filled with clear to straw-colored fluid. Larger cysts were sometimes noted to be hemorrhagic. Histologically, the cysts were lined by a thin fibrous band that separated the cyst from the neoplastic cells. In comparison with their solid counterparts, cystic PanNETs were less likely to demonstrate tumor necrosis (6%; P=0.04), perineural invasion (8%; P<0.001), vascular invasion (4%; P<0.001), regional lymph node metastasis (13%; P<0.001), and synchronous distant metastasis (4%; P=0.015). The neoplastic cells of the cystic PanNETs were well differentiated (n=53, 100%) with a low mitotic rate and low Ki-67 proliferation index (range, 0.2% to 11%; mean, 1.8%). On the basis of both the American Joint Cancer Committee and European Neuroendocrine Tumor Society staging systems, the majority of cystic PanNETs presented at a lower pathologic stage as compared with solid PanNETs. In summary, cystic PanNETs are a distinctive subgroup of PanNETs with unique clinical, radiographic, and pathologic features.

Primary pancreatic cystic neoplasms of the pancreas revisited. Part IV: rare cystic neoplasms

Primary pancreatic cystic neoplasms are being recognized with increasing frequency due to modern imaging techniques. In addition to the more common cystic neoplasms-serous cystadenoma, primary mucinous cystic neoplasm, and intraductal papillary mucinous neoplasm-there are many other less common neoplasms that appear as cystic lesions. These cystic neoplasms include solid pseudopapillary neoplasm of the pancreas (the most common rare cystic neoplasm), cystic neuroendocrine neoplasm, cystic degeneration of otherwise solid neoplasms, and then the exceedingly rare cystic acinar cell neoplasm, intraductal tubular neoplasm, angiomatous neoplasm, lymphoepithelial cysts (not true neoplasms), and few others of mesenchymal origin. While quite rare, the pancreatic surgeon should at the least consider these unusual neoplasms in the differential diagnosis of potentially benign or malignant cystic lesions of the pancreas. Moreover, each of these unusual neoplasms has their own natural history/tumor biology and may require a different level of operative aggressiveness to obtain the optimal outcome.

EUS-FNA for pancreatic neuroendocrine tumors: a tertiary cancer center experience

OBJECTIVES

Pancreatic neuroendocrine tumors (PNET) are fairly uncommon. Recent data highlight the importance of EUS in diagnosis of PNET. With this background, we decided to review our experience from a tertiary cancer center with regard to the presentation and clinical features of PNET and the diagnostic utility of EUS-FNA in this scenario.

METHODS

We identified patients who underwent EUS at our institution between January 1st 2001 and December 31st 2009 for a suspected PNET. Data on clinical features, cross-sectional imaging findings, EUS findings, and cytology results were collected.

RESULTS

A total of 81 patients were referred for EUS-FNA for a suspected PNET. Mean age was 58.1 years. There were 41 (50.6%) males. PNET was found incidentally in 38 (46.9%) patients. Computed tomography scanning identified a pancreatic mass in 72 out of 79 (91.1%) cases. Mean diameter of the largest lesion seen on EUS was 27.5 mm (range: 6.9-80 mm). The most common site (34; 42%) was the head of the pancreas. EUS-FNA correctly confirmed a PNET in 73 out of 81 cases with diagnostic accuracy of 90.1%. Seven (8.6%) out of 81 patients had functional lesions, including three gastrinomas and four insulinomas. Liver metastases were found in 31 out of 81 (38.3%) cases. Of the 31 patients with liver metastasis, the mean diameter of lesions on EUS was 33.9 mm compared with 23.5 mm in patients without liver metastasis (P = 0.005).

CONCLUSION

EUS-FNA is a reliable modality for further characterization of suspected lesions and for establishing a tissue diagnosis. The occurrence of complications of EUS-FNA in this setting is low. Non-functional PNET are more frequently encountered than functional PNET.

Solid tumors of the pancreas can put on a mask through cystic change

Background

Solid pancreatic tumors such as pancreatic ductal adenocarcinoma (PDAC), solid pseudopapillary tumor (SPT), and pancreatic endocrine tumor (PET) may occasionally manifest as cystic lesions. In this study, we have put together our accumulated experience with cystic manifestations of various solid tumors of the pancreas.

Methods

From 2000 to 2006, 376 patients with pancreatic solid tumor resections were reviewed. Ten (2.66%) of these tumors appeared on radiological imaging studies as cystic lesions. We performed a retrospective review of medical records and pathologic findings of these 10 cases.

Results

Of the ten cases in which solid tumors of the pancreas manifested as cystic lesions, six were PDAC with cystic degeneration, two were SPT undergone complete cystic change, one was cystic PET, and one was a cystic schwannoma. The mean tumor size of the cystic portion in PDAC was 7.3 cm, and three patients were diagnosed as 'pseudocyst' with or without cancer. Two SPT were found incidentally in young women and were diagnosed as other cystic neoplasms. One cystic endocrine tumor was preoperatively suspected as intraductal papillary mucinous neoplasm or mucinous cystic neoplasm.

Conclusions

Cystic changes of pancreas solid tumors are extremely rare. However, the possibility of cystic manifestation of pancreas solid tumors should be kept in mind.

Validation of five contemporary prognostication systems for primary pancreatic endocrine neoplasms: results from a single institution experience with 61 surgically treated cases

BACKGROUND

Presently, several systems for the prognostication of pancreatic endocrine neoplasms (PENs) exist and the most appropriate classification system has not been clearly defined. This study aims to validate the performance of the 2004 World Health Organization (WHO), European Neuroendocrine Tumor Society (ENETS), Memorial Sloan-Kettering Cancer Center (MSKCC), American Joint Committee for Cancer (AJCC) TNM staging and Bilimoria criteria in a cohort of patients with PENs who underwent surgery at a single institution.

METHODS

This study is a retrospective review of 61 consecutive patients who underwent surgical treatment for PEN. Actuarial disease-specific survival (DSS) of all 61 patients and recurrence-free survival (RFS) of 53 patients who had curative resection were analysed.

RESULTS

On univariate analyses, tumour size ≥50 mm, non-curative resection, lymph node involvement, presence of distant metastases, presence of necrosis, mitotic count ≥2/10 hpf and poor differentiation were associated with decreased DSS. Tumour size ≥50 mm, lymph node involvement, lymphovascular invasion, presence of necrosis and mitotic count ≥2/10 hpf were associated with decreased actuarial RFS. All five staging systems were useful in stratifying the 61 patients according to actuarial DSS. However, the MSKCC grading and ENETS grading systems were not statistically significant in stratifying DSS in the 61 patients. In the 53 patients who underwent curative resection, the WHO, ENETS, MSKCC, AJCC staging and the MSKCC grading systems were successful in stratifying the patients according to actuarial RFS. However, the Bilimoria scoring and ENETS grading systems were not useful in prognosticating these 53 patients.

CONCLUSION

All five classification systems were useful for the prognostication of surgically treated PENs in our patient cohort.

Pancreatic endocrine tumors: a large single-center experience

OBJECTIVES

Pancreatic endocrine tumors (PETs) are infrequent, which makes large experiences unlikely. Our aim was to describe a large single-center experience with PETs and the use of endoscopic ultrasound (EUS) and a cancer staging system (TNM).

METHODS

This study involves a retrospective analysis of 86 patients (44 men; age, 58 +/- 14 years) who underwent EUS-fine needle aspiration (EUS-FNA). Immunohistochemistry was used. Lesions were classified as recommended by TNM classification.

RESULTS

Typical EUS features were well-demarcated, hypoechoic, solid, homogeneous lesions. Ninety percent had the diagnosis obtained by EUS-FNA. Twelve PETs (14%) were functioning, 8 (9.3%) were cystic, and 14 (16%) were 10 mm or smaller. Nonfunctional PETs and larger lesions were more advanced. The TNM stage was I in 24, II in 10, III in 18, and IV in 34 patients. Sixteen patients (27%) died, and 30 patients (52%) had progression/recurrence during the follow-up (34 +/- 27 months). TNM stage and surgery with curative intent were related to progression. The overall 5-year survival was 60%. The mean survival time was 94 +/- 12 months for stage I, 52 +/- 12 months for stage III, and 54 +/- 7 months for stage IV (P = 0.06).

CONCLUSIONS

Nonfunctional PETs were more common and advanced. The EUS-FNA has a high accuracy for diagnosing PETs. Progression and poorer survival were associated with TNM stage.

Cystic pancreatic endocrine tumors: an endoscopic ultrasound-guided fine-needle aspiration biopsy study with histologic correlation

BACKGROUND

Cystic pancreatic endocrine tumors (PETs) are rare neoplasms with a preoperative diagnostic challenge. The aim of this study was to evaluate the preoperative diagnostic strategy for these tumors and to assess the clinical and pathologic characteristics.

METHODS

Six cases of cystic PET were retrospectively enrolled. Endoscopic ultrasound-guided fine-needle aspiration biopsy (EUS-FNAB) was performed in 4 cases. All cytomorphologic data from conventional smears, ThinPrep preparations, and cell block preparations were reported in detail.

RESULTS

There were 3 male and 3 female patients with a mean age of 52.3 years. Tumor size ranged from 10 mm to 60 mm (mean, 29.8 mm). EUS-FNAB contributed to an accurate diagnosis in all cases. Cytologically, loosely cohesive aggregates and single cells were predominant. Cells were small and typically plasmacytoid, with occasional cytoplasmic vacuolization. Nuclei were round or oval, uniform, with finely and evenly distributed chromatin. Immunocytochemistry confirmed the endocrine differentiation. Histologic findings were typical for endocrine proliferation. All tumors were well differentiated.

CONCLUSIONS

Cystic PET is an unusual finding that presents diagnostic challenges for both endoscopists and cytologists. EUS-FNAB with the Thinprep preparation technique and cell block material were found to be helpful in improving diagnostic accuracy. Immunocytochemical staining with endocrine markers confirmed the diagnosis.

Calponin is expressed in serous cystadenomas of the pancreas but not in adenocarcinomas or endocrine tumors

The diagnosis of serous microcystic adenoma (SMA) is usually straightforward. For small biopsies and/or unusual variants, the differential diagnosis includes other pancreatic or metastatic neoplasms showing cystic or clear cell features. We evaluated immunostains for potential use in the diagnosis of SMA. Cases of SMA were identified from archival files. Tissue cores (2 per block) were arrayed to create a microarray of cores measuring 2mm each. Additionally, microarrays previously constructed from 56 pancreatic adenocarcinomas (PACs) and 64 pancreatic endocrine tumors (PENs) were studied. The microarrays were stained with calponin, chromogranin, CD10, alpha-inhibin, and monoclonal neuron-specific enolase (m-NSE). Subsequently, some were stained with MUC6, melan-A, D2-40, h-caldesmon, smooth muscle actin, and smooth muscle myosin. For SMAs, staining was seen with calponin (85.2%), alpha-inhibin (96.2%), and m-NSE (96.2%). Focal weak staining was seen with MUC6 (65%). All SMAs were negative with chromogranin, CD10, melan-A, D2-40, h-caldesmon, smooth muscle actin, and smooth muscle myosin. In contrast, calponin was negative in all PACs and PENs. Staining for alpha-inhibin was absent in PACs and present in 4.1% of PENs; whereas immunoreactivity for m-NSE was present in 26.8% of PACs and 73.7% of PENs. Chromogranin staining was present in 9.1% of PACs and 100% of PENs. An immunohistochemical profile of staining with calponin, alpha-inhibin, and m-NSE and absent staining with chromogranin supports the diagnosis of SMA, and distinguishes SMA from PAC and PEN. Calponin and alpha-inhibin are the most useful positive markers for SMA, and are negative in most entities in the differential diagnosis.

Cystic Neoplasms of the Pancreas: Current Diagnostic Modalities and Management

Cystic neoplasm of the pancreas is a relatively uncommon condition covering a wide spectrum of pathology. The increasing incidence as a result of routine imaging tests in asymptomatic patients presents a diagnostic and therapeutic problem to the clinician. This paper discusses the role of the various investigative modalities in the management of cystic neoplasia of the pancreas. Key words: Frantz tumour, Intraductal papillary mucinous neoplasm, Mucinous cystadenoma, Mucinous cystadenocarcinoma, Mucinous neoplasm of the pancreas, Solid pseudopapillary neoplasm

Cystic pancreatic neuroendocrine neoplasms with uncertain malignant potential: report of two cases

Neuroendocrine tumors of the pancreas (NETP) represent only 1%-2% of all pancreatic neoplasms. They can be classified as functioning or non-functioning, respectively, according to the presence or absence of paraneoplastic syndrome. Case 1 concerned a 70-year-old woman with a cystic lesion of the pancreatic head and body. All tumor markers were negative. The patient underwent a distal pancreatectomy. The histology revealed a well-differentiated endocrine tumor with uncertain malignant potential. Case 2 was a 61-year-old man with chronic polyserositis. The serum tumor markers were negative, while he was strongly positive for intracystic tumor markers carcinoembryonic antigen, carbohydrate antigen (CA) 19-9, and CA 125. The patient underwent a cephalo-pancreatic duodenectomy. The preoperative differential diagnosis of cystic NETP is still a challenge due to the high rate of the nonfunctional variant. Although cystic NETPs are well differentiated, they are still tumors with a malignant potential, and therefore an early diagnosis and radical surgical resection could be associated with a better long-term survival.

Incidental cystic neoplasms of pancreas: what is the optimal interval of imaging surveillance?

BACKGROUND

The optimal interval of imaging studies for surveillance of incidental pancreatic cystic neoplasms is not known.

OBJECTIVE

A retrospective analysis of longitudinal medical records of patients with pancreatic cystic neoplasms was performed to examine the natural history of incidentally detected cystic pancreatic neoplasms with respect to the development of significant growth and to identify predictors of such growth.

RESULTS

After excluding patients with small (<10 mm) cysts (N = 144) and inadequate clinical follow-up of less than 6 months (N = 79) and those with a clinical diagnosis of pancreatic pseudocysts, serous cystadenoma, main duct intraductal papillary mucinous neoplasm (N = 29), and neuroendocrine tumor (N = 3), in total, 166 cysts in 150 patients were available for analysis. The working diagnoses on these cysts (based on clinical, radiological features, aspiration cytology, cyst fluid analysis, and surgical pathology data when available) were mucinous cystic neoplasm in 117 and branch-type intraductal papillary mucinous neoplasm in 49. The mean standard error (SE) initial size of these cysts was 2 (0.1) cm. Over a median period of follow-up of 32 (IQR [inter-quartile range] 19-48) months, 89% of all the cysts did not show significant growth during the follow-up. In a multivariate Cox proportional hazards model, the initial size of the cystic lesion was an independent predictor of significant growth during follow-up (relative risk 1.28, 95% confidence interval [CI] 1.08-1.61, P= 0.01); the only other significant variable was the presence of intracystic or mural nodule (relative risk 38.6, 95% CI 2.3-654, P= 0.01).

CONCLUSION

Most incidentally detected cystic neoplasms of the pancreas did not have significant growth during follow-up. Such growth is unlikely to occur before 2 yr of the baseline evaluation, and we suggest that the optimal imaging interval during follow-up of these patients should be at 2 yr from the baseline evaluation, particularly in cystic lesions 3.0 cm or less in size and without intracystic or mural nodules.

Cystic pancreatic endocrine neoplasms: a distinct tumor type?

BACKGROUND

Cystic pancreatic endocrine neoplasms (CPENs) are considered rare, and their behavior is thought to be similar to that of solid pancreatic endocrine neoplasms (PENs). This study aims to describe the characteristics of CPENs in a large patient cohort.

STUDY DESIGN

We performed a retrospective review of 170 patients who underwent resections for PENs at Massachusetts General Hospital from 1977 to 2006. Twenty-nine patients (51% men, mean age 53) with CPENs were compared with 141 patients with solid PENs. Differences in clinical presentation, pathologic and radiographic features, and survival were described.

RESULTS

CPENs comprised 17% of all PENs (29 of 170) and 5.4% of all resected cystic pancreatic neoplasms(29 of 535). Ten (34%) were purely cystic and 19 (66%) were partially cystic. Compared with solid PENs, CPENs were larger (49 mm versus 23.5 mm, p < 0.05), more likely symptomatic (73% versus 45%, p < 0.05), and more likely nonfunctional (80% versus 50%, p < 0.05). They expressed synaptophysin (100%), chromogranin (82%), and cytokeratin (CK)-19 (24%). Multiple endocrine neoplasia type 1 (MEN-1) was 3.5 times more common in CPENs than in solid tumors (21% versus 6%, p < 0.05). No significant difference was found in location, propensity for metastasis, invasion, or 5-year survival (87% versus 77%, p=0.38).

CONCLUSIONS

This series, the largest report of CPENs in the literature, shows that CPENs are more common than previously thought, so they should be included in the differential of the cystic lesions of the pancreas. CPENs are larger and more likely to be symptomatic then solid PENs. They are also more likely to be associated with MEN-1 and to be nonfunctional, suggesting they may be a distinct tumor type.