Recurrent mucinous cystic neoplasm of the mesentery in a young nullipara mimicking as ovarian carcinoma.

INRODUCTION: Mucinous cystic neoplasms are rare tumors. They may originate from either ovaries, pancreas, or other intra-abdominal sites, but rarely from the mesentery. CASE HISTORY: A 22-year-old nulliparaous woman, who had undergone laparascopic bilateral cystectomy for recurrent ovarian mass, presented with pain in abdomen, backache, and menstrual irregularities. Provisionally diagnosed as ovarian carcinoma, she underwent bilateral salpingo-oophorectomy and sigmoid colectomy. However, the histopathological examination revealed mucinous cystic neoplasm of the mesentery. DISCUSSION: Thus, complete resection of the cysts with meticulous gross and histopathological examination remains the gold standard to differentiate mucinous cystic neoplasm (MCN) of the mesentery from its mimics, especially malignant counterparts, enabling clinicians to adequately manage such patients. Here, we present a case of recurrent MCN of mesentery (mesocolon), mimicking as ovarian carcinoma confirmed on histopathological examination, in a young adult.

Genomic analysis of primary epithelial neoplasms of the seminal vesicle identifies a subset of mucinous cystic tumours driven by KRAS mutations.

BACKGROUND: Carcinomas of the seminal vesicle are exceedingly rare, with a limited number of cases described in the literature. Reported cases span a relatively wide morphological spectrum, and their genomic features remain unexplored. DESIGN: In this study, we interrogated five primary epithelial neoplasms of the seminal vesicle using a targeted DNA sequencing platform (OncoPanel, 447 genes). RESULTS: The tumours included one adenocarcinoma with intestinal phenotype presenting after external beam radiation (for prostatic adenocarcinoma), one carcinoma with Müllerian-type clear cell phenotype, two mucinous tumours resembling low-grade mucinous neoplasms of the appendix (LAMN) and one mucinous cystadenoma. The post-radiation mucinous adenocarcinoma had genomic findings consistent with bi-allelic inactivation of TP53, as well as multiple copy-number changes with regional and chromosomal arm-level copy-number losses. The Müllerian-type clear cell carcinoma exhibited a complex copy-number profile with numerous regional and arm-level copy-number changes, as well as focal amplification events, including copy-number gain of 8q and amplification of a region within 20q13. Both low-grade mucinous tumours resembling LAMN harboured hot-spot gain-of-function KRAS variants (p.G12V and p.G13D) as the only genomic alteration. No genomic alterations were detected inthe lesion diagnosed as mucinous cystadenoma. CONCLUSION: Our results suggest that primary low-grade mucinous neoplasms of the seminal vesicle may represent a distinct entity equivalent to appendiceal counterparts, driven by gain-of-function variants of RAS GTPases. The remaining tumours showed genomic features that closely resembled those of neoplasms with comparable phenotypes and/or biological characteristics arising in other sites, suggesting that they could be managed similarly, with special considerations related to their anatomical location.

Variations in subtle cystic tumors of the atrioventricular node: Five autopsy cases.

Cystic tumor of the atrioventricular node (CTAVN) is the most common primary cardiac tumor cause of sudden death but is rarely found during forensic autopsy. We present five autopsy cases of sudden death from undiagnosed CTAVN. The tumors varied in their histological appearance, which may be related to their variation in clinical presentation. Some of the cases had been diagnosed with epilepsy before death; it seems that syncopal attacks caused by CTAVN may be misdiagnosed as epilepsy. When performing forensic autopsy, CTAVN should be considered in the differential diagnosis of sudden death. Careful examination of the cardiac conduction system is important in every sudden death case regardless of age.

The Deception of Pancreas Cyst Surveillance: A Case Study.

Pancreatic cysts are a growing pandemic around the world. Intrapapillary mucinous neoplasms are the most common type of pancreatic cysts and given their premalignant nature, guidelines recommend surveillance. This case study and discussion addresses the five existing guidelines published to help clinicians manage patients with intraductal papillary mucinous neoplasms and illustrates how, despite guidelines and close surveillance, intraductal papillary mucinous neoplasms can transform into pancreatic adenocarcinoma.

Association of high-risk stigmata and worrisome features with advanced neoplasia in intraductal papillary mucinous neoplasms (IPMN): A systematic review.

BACKGROUND: This systematic review aimed to assess the diagnostic accuracy of the International Consensus Fukuoka Guidelines (ICG2017) in identifying high-risk lesions of Intraductal Papillary Mucinous Neoplasms (IPMNs). METHODS: The ICG2017 revision committee conducted a comprehensive literature review to establish evidence-based statements on IPMNs. The review focused on articles examining the diagnostic value of imaging features (e.g., cyst or main pancreatic duct diameter), clinical symptoms associated with IPMN, and serum biomarkers. Five clinical questions regarding high-risk stigmata (HRS) and worrisome features (WF) in the ICG2017 guidelines were addressed. RESULTS: A total of 210 articles were reviewed. The findings revealed a significant association between the presence of mural nodules ≥5 mm in diameter or solid components with contrast enhancement and the diagnosis of high-grade dysplasia or invasive carcinoma. Contrast-enhanced diagnostic tools, such as CT, MRI, or EUS, demonstrated the highest prediction rate and were recommended. Positive cytology was identified as an HRS, while symptoms like acute pancreatitis and cyst diameter growth ≥2.5 mm per year were considered WFs. The use of nomograms and multiple diagnostic factors was recommended for optimal IPMN management. CONCLUSIONS: This systematic review provides evidence supporting the improved diagnostic accuracy of ICG2017 in identifying high-risk lesions of IPMN. The multidisciplinary incorporation of HRS and WF based on imaging findings and clinical symptoms is crucial. These findings should inform the revision of ICG2017, enhancing the evaluation and management of IPMN patients. By implementing these recommendations, clinicians can make more informed decisions, leading to better diagnosis and treatment outcomes for high-risk IPMN cases.

Feasibility of Surveillance for Mucinous Cystic Neoplasm of the Pancreas: A Multi-Institutional Retrospective Study of 328 Patients by the Japanese Pancreatic Society.

OBJECTIVE: We aimed to elucidate the feasibility of surveillance of patients with mucinous cystic neoplasm (MCN). METHODS: We performed a retrospective, multi-institutional study of 328 patients who underwent surgery for MCN at 18 Japanese institutions. Patients with MCN were divided into an immediate surgery group and a surveillance group, which underwent surgery after surveillance. RESULTS: The median surveillance period until surgery in the surveillance group was 27 months (range, 7-165 months). Compared with the immediate surgery group, the surveillance group showed smaller tumor diameter (46 vs 50 mm, P = 0.01), more frequent laparoscopic approach (58% vs 37%, P < 0.01), and less frequent malignancy (7% vs 15%, P = 0.03). The new appearance of mural nodules and elevation of serum tumor markers were associated with malignancy in the surveillance group. Two patients in the surveillance group experienced postoperative recurrence, although there was no significant difference in recurrence or disease-free survival between the two groups. In the surveillance group, the 1-, 5-, and 10-year cumulative incidence rates of malignant MCN were 0.8%, 5.6%, and 36.5%, respectively. CONCLUSION: As the risk of progression to malignant MCNs increases over the long term, MCNs should be resected rather than subjected to unnecessary surveillance.

[Cystic pancreatic lesions-indications, timing and reasons for surveillance]. / Pankreaszysten ­ Indikationen, Zeitpunkt und Rationale für eine Surveillance.

BACKGROUND: Cystic pancreatic lesions are detected incidentally at an increasing rate. Often, the patients present asymptomatically. Hence, the resulting clinical consequences remain challenging and unsettling for both physicians and patients. OBJECTIVES: Status of current recommendations in handling cystic pancreatic lesions. MATERIALS AND METHODS: Selective literature search of PubMed while taking current guidelines into account. RESULTS: Correct diagnostic classification of the cystic lesion is crucial since further action depends on the type of cystic lesion. Resection is generally recommended for mucinous cystic neoplasms (MCN), solid pseudopapillary neoplasms (SPN), and intraductal papillary mucinous neoplasms (IPMN) with relevant risk criteria such as prominent main-duct dilation. Surveillance is recommended for IPMN without risk criteria, as long as comorbidities and life expectancy of the patient will allow preventive resection over the years. SCNs are benign and only symptomatic SCNs require resection. Inflammatory pancreatic cysts should only be treated under certain circumstances.

Long-term surveillance of branch-duct intraductal papillary mucinous neoplasms without worrisome or high-risk features.

INTRODUCTION: Long-term data evaluating clinical outcomes in patients with branch-duct Intraductal papillary mucinous neoplasms (BD-IPMN) without high-risk stigmata (HRS) or worrisome features (WF) remain limited. METHODS: This observational cohort study included all patients diagnosed with BD-IPMN without HRS or WF between 2003 and 2019 who were enrolled in a prospective surveillance program. Time-to-progression analysis was performed using a cumulative incidence function plot and survival analysis was conducted using Kaplan-Meier. RESULTS: The median follow-up time for the 267 patient cohort was 44.5 months (interquartile range [IQR]: 24.1-72.2). Radiographic cyst growth was observed in 123 (46.1%) patients; 65 (24.3%) patients progressed to WF/HRS. Twenty-six (9.7%) patients were selected for resection during surveillance: 21 (80.8%) WF, 4 (15.4%) HRS; 1 (3.9%) transformed to mixed-duct. Of all the patients who underwent resection, 5 (19.2%) had adenocarcinoma, and 1 (3.8%) had carcinoma-in-situ. The probability of any radiographic progression was 21.3% (5-year) and 51.3% (10-year). For the entire cohort, there was 1.1% mortality secondary to pancreatic adenocarcinoma and 8.2% all-cause mortality. The 5-year overall survival rate was 91.5%, and at 10 years, 81.5%. CONCLUSION: Approximately one in four patients with nonworrisome BD-IPMN have progression to WF/HRS stigmata during surveillance. However, the risk of malignant transformation remains low. Surveillance strategy remains prudent in this patient population.

Enhancing Mural Nodules in the Main Pancreatic Duct of Main and Mixed Types of Intraductal Papillary Mucinous Neoplasms: Does Size Matter in Malignancy Risk?

Background/Aims: Most guidelines recommend surgical resection of all main duct (MD) and mixed-type (MT) intraductal papillary mucinous neoplasms (IPMNs) in suitable patients. However, there is little evidence regarding the malignancy risk of enhancing mural nodules (EMNs) that are present only in the main pancreatic duct (MPD) in patients with MD- and MT-IPMNs. Therefore, this study aimed to identify the clinical and morphological features associated with malignancy in MD- and MT-IPMNs with EMNs only in the MPD. Methods: We retrospectively enrolled 50 patients with MD- and MT-IPMNs with EMNs only in the MPD on contrast-enhanced magnetic resonance imaging. We evaluated the clinical characteristics and preoperative radiologic imaging results of MPD morphology and EMN size and analyzed the risk factors associated with malignancy. Results: Histological findings of EMNs were low-grade dysplasia (38%), malignant lesions (62%), high-grade dysplasia (34%), and invasive carcinoma (28%). On the receiver operating characteristic curve, the cutoff value of EMN size on magnetic resonance imaging for best predicting malignancy was 5 mm (sensitivity, 93.5%; specificity, 52.6%; area under the curve, 0.753). Multivariate analysis showed that only EMN >5 mm (odds ratio, 27.69; confidence interval, 2.75 to 278.73; p=0.050) was an independent risk factor for malignancy. Conclusions: EMNs of >5 mm are associated with malignancy in patients with MD- and MT-IPMNs with EMNs that are present only in the MPD, in accordance with the international consensus guidelines.

Malignancy risk factors and prognostic variables of pancreatic mucinous cystic neoplasms in Chinese patients.

BACKGROUND: Pancreatic mucinous cystic neoplasms (MCNs) represent one of the precursor lesions of pancreatic ductal adenocarcinoma, and their detection has been facilitated by advances in preoperative imaging. Due primarily to the rarity of MCNs, however, there is limited knowledge regarding the prognostic variables and high-risk factors for malignant transformation. A more comprehensive and nuanced approach is necessary to fill this gap and provide a basis for improved treatment decisions and patient outcomes. AIM: To investigate the high-risk factors associated with malignant MCNs and to explore the prognostic factors of MCN with associated invasive carcinoma (MCN-AIC). METHODS: All cases of resected MCNs from a single high-volume institution between January 2012 and January 2022 were retrospectively reviewed. Only cases with ovarian-type stroma verified by progesterone receptor staining were included. Preoperative features, histological findings and postoperative course were documented. Multivariate logistic regression was employed to investigate variables related to malignancy. Survival analysis was performed using the Kaplan-Meier curve, and the prognostic factors were assessed to evaluate the postoperative course of patients with MCN-AIC. RESULTS: Among the 48 patients, 36 had benign MCNs, and 12 had malignant MCNs (1 high-grade atypical hyperplasia and 11 MCN-AIC). Age, tumour size, presence of solid components or mural nodules and pancreatic duct dilatation were identified as independent risk factors associated with malignancy. The follow-up period ranged from 12 mo to 120 mo, with a median overall survival of 58.2 mo. Only three patients with MCN-AIC died, and the 5-year survival rate was 70.1%. All 11 cases of MCN-AIC were stage I, and extracapsular invasion was identified as a prognostic factor for poorer outcomes. CONCLUSION: The risk factors independently associated with malignant transformation of MCNs included age, tumour size, presence of solid components or mural nodules, and pancreatic duct dilatation. Our study also revealed that encapsulated invasion was a favourable prognostic factor in MCN-AIC patients.

Innovation in the Surgical Management of Pancreatic Cystic Neoplasms: Same Operations, Narrower Indications, and an Individualized Approach to Decision-Making.

Historically, the management of pancreatic cystic neoplasms (PCN) has been operative. Early intervention for premalignant lesions, including intraductal papillary mucinous neoplasms (IPMN) and mucinous cystic neoplasms (MCN), offers an opportunity to prevent pancreatic cancer-with potential decrement to patients' short-term and long-term health. The operations performed have remained fundamentally the same, with most patients undergoing pancreatoduodenectomy or distal pancreatectomy using oncologic principles. The role of parenchymal-sparing resection and total pancreatectomy remains controversial. We review innovations in the surgical management of PCN, focusing on the evolution of evidence-based guidelines, short-term and long-term outcomes, and individualized risk-benefit assessment.

Genetic analysis for mucinous ovarian carcinoma with infiltrative and expansile invasion and mucinous borderline tumor: a retrospective analysis.

BACKGROUND: Mucinous carcinoma (MC) is a histological subtype of ovarian cancer that has a worse prognosis at advanced stages than the most prevalent histological subtype, high-grade serous carcinomas. Invasive patterns have been recognized as prognostic factors for MCs. MCs with infiltrative invasion were more aggressive than those with expansile invasion. MC with an expansile pattern exhibited behavior similar to mucinous borderline tumors (MBT). However, genomic analysis of invasive patterns is insufficient. This study aimed to compare genetic information between groups with MC and infiltrative invasion (Group A) and those with MC with expansile invasion or MBT (Group B). METHODS: Ten cases each of MC with infiltrative invasion, MC with expansile invasion, and MBT between 2005 and 2020 were identified. Deoxyribonucleic acid (DNA) extraction from formalin-fixed paraffin-embedded tissues was performed, and cases with DNA fragmentation or the possibility of DNA fragmentation were excluded. Mutant base candidates and tumor mutation burden (TMB) values (mutations/megabase) were calculated. RESULTS: After assessing the quality of purified DNA, seven cases of MC with infiltrative invasion, five cases of MC with expansile invasion, and three cases of MBT were included. More patients in group A experienced recurrence or progression (p < 0.01) and died of disease (p = 0.03). Moreover, the TMB value was statistically higher in group A than in group B (p = 0.049). There were no statistical differences in the incidence of the mutations of KRAS, TP53, and CREBBP. KRAS, TP53, and CREBBP mutations were discovered in 8/15 (53.3%), 6/15 (40.0%), and 5/15 (33.3%) cases, respectively. CONCLUSIONS: Genetic analysis revealed that Group A had higher TMB than Group B. Therefore, this result might be useful for future treatment.

It is not necessary to resect all mucinous cystic neoplasms of the pancreas: current guidelines do not reflect the actual risk of malignancy.

BACKGROUND: Mucinous Cystic Neoplasms (MCN) of the pancreas are premalignant cysts for which current guidelines support pancreatic resection. The primary aim of this systematic review and meta-analysis is to define the pooled rate of malignancy for MCN. METHODS: A systematic review of eligible studies published between 2000 and 2021 was performed on PubMed and Embase. Primary outcome was rate of malignancy. Data regarding high-risk features, including cyst size and mural nodules, were collected and analyzed. RESULTS: A total of 40 studies and 3292 patients with resected MCN were included in the final analysis. The pooled rate of malignancy was 16.1% (95%CI 13.1-19.0). The rate of malignant MCN in studies published before 2012 was significantly higher than that of studies published after recent guidelines were published (21.0% vs 14.9%, p < 0.001). Malignant MCN were larger than benign (mean difference 25.9 mm 95%CI 14.50-37.43, p < 0.001) with a direct correlation between size and presence of malignant MCN (R2 = 0.28, p = 0.020). A SROC identified a threshold of 65 mm to be associated with the diagnosis of malignant MCN. Presence of mural nodules was associated with the diagnosis of a malignant MCN (OR = 4.34, 95%CI 3.00-6.29, p < 0.001). CONCLUSION: Whereas guidelines recommend resection of all MCN, the rate of malignancy in resected MCN is 16%, implying that surveillance has a role in most cases, and that surgical selection criteria are warranted. Size and presence of mural nodules are significantly associated with an increased risk of malignant degeneration, small MCN and without mural nodules can be considered for surveillance.

How to do an enucleation of a branch-duct intraductal papillary and mucinous neoplasm of the head of the pancreas (with video).

'How I do' video of an enucleation of cystic lesion of the pancreas.

Branch duct-intraductal papillary mucinous neoplasms (BD-IPMNs): an MRI-based radiomic model to determine the malignant degeneration potential.

BACKGROUND: Branch duct-intraductal papillary mucinous neoplasms (BD-IPMNs) are the most common pancreatic cystic tumors and have a low risk of malignant transformation. Features able to early identify high-risk BD-IPMNs are lacking, and guidelines currently rely on the occurrence of worrisome features (WF) and high-risk stigmata (HRS). AIM: In our study, we aimed to use a magnetic resonance imaging (MRI) radiomic model to identify features linked to a higher risk of malignant degeneration, and whether these appear before the occurrence of WF and HRS. METHODS: We retrospectively evaluated adult patients with a known BD-IPMN who had had at least two contrast-enhanced MRI studies at our center and a 24-month minimum follow-up time. MRI acquisition protocol for the two examinations included pre- and post-contrast phases and diffusion-weighted imaging (DWI)/apparent diffusion coefficient (ADC) map. Patients were divided into two groups according to the development of WF or HRS at the end of the follow-up (Group 0 = no WF or HRS; Group 1 = WF or HRS). We segmented the MRI images and quantitative features were extracted and compared between the two groups. Features that showed significant differences (SF) were then included in a LASSO regression method to build a radiomic-based predictive model. RESULTS: We included 50 patients: 31 in Group 0 and 19 in Group 1. No patients in this cohort developed HRS. At baseline, 47, 67, 38, and 68 SF were identified for pre-contrast T1-weighted (T1-W) sequence, post-contrast T1-W sequence, T2-weighted (T2- W) sequence, and ADC map, respectively. At the end of follow-up, we found 69, 78, 53, and 91 SF, respectively. The radiomic-based predictive model identified 16 SF: more particularly, 5 SF for pre-contrast T1-W sequence, 6 for post-contrast T1-W sequence, 3 for T2-W sequence, and 2 for ADC. CONCLUSION: We identified radiomic features that correlate significantly with WF in patients with BD-IPMNs undergoing contrast-enhanced MRI. Our MRI-based radiomic model can predict the occurrence of WF.

Clinical Outcomes of Intraductal Papillary Mucinous Neoplasms With Dilatation of the Main Pancreatic Duct.

BACKGROUND & AIMS: Dilatation of the main pancreatic duct (MPD) has been a surgical indication for intraductal papillary mucinous neoplasms (IPMNs). Few studies have investigated long-term outcomes of IPMNs with MPD dilatation. METHODS: Among 3610 patients diagnosed with pancreatic cysts between 1994 and 2021, we identified 2829 IPMN patients, including 282 patients with MPD ≥5 mm, and examined short-term (≤6 months) and long-term risks of pancreatic carcinoma. Utilizing competing risks proportional hazards models, we estimated subdistribution hazard ratios for incidence of pancreatic carcinoma with adjustment for potential confounders. RESULTS: In analyses of short-term outcomes of the 282 patients with MPD dilatation, 72 (26%) patients were diagnosed with pancreatic carcinoma based on surgical or nonsurgical exploration. During long-term follow-up of 168 patients, we documented 24 (14%) patients diagnosed with pancreatic carcinoma (18 with IPMN-derived carcinoma and 6 with concomitant ductal adenocarcinoma). The patients with the MPD = 5-9.9 mm had cumulative incidence rates of pancreatic carcinoma diagnosis of 8.1% (95% confidence interval [CI], 4.3%-13.5%) and 10.0% (95% CI, 5.5%-15.9%) at 2 and 5 years, respectively; and the patients with the MPD ≥10 mm had the corresponding rates of 16.0% (95% CI, 3.6-36.5%) and 33.3% (95% CI, 10.3%-58.8%). The multivariable subdistribution hazard ratios were 2.78 (95% CI, 1.57-4.90) and 7.00 (95% CI, 2.58-19.0) for the MPD = 5-9.9 mm and ≥10 mm (vs <5 mm), respectively. CONCLUSIONS: IPMNs with MPD dilatation at baseline were associated with higher prevalence and incidence of pancreatic carcinoma compared with IPMNs with no MPD dilatation.

Pancreatic serous cystic neoplasm mimicking intraductal papillary mucinous neoplasm: Two case reports and literature review.

RATIONALE: Serous cystic neoplasms (SCNs) are treated as benign lesions. It is widely known that SCN rarely have a connection with the main pancreatic duct (MPD), which helps differentiate them from other cystic lesions, such as intraductal papillary mucinous neoplasm (IPMN). However, very rare cases where the SCN appears connected to the MPD cause diagnostic confusion. PATIENT CONCERNS: We present 2 patients with SCN (1 male, 54, and 1 female, 42). Both patients were asymptomatic, without abnormal laboratory results. DIAGNOSIS: In both cases, abdominopelvic computed tomography and pancreatic magnetic resonance imaging scans revealed a multilobulated cystic lesion in communication with the MPD. Since the size of each patient's lesion was >3 cm and there was connectivity with the MPD, it was strongly suspected to be a branch duct-type IPMN with worrisome features rather than SCN and surgical intervention was considered. INTERVENTIONS: Both neoplasms were misdiagnosed as IPMN due to appearing connected with the MPD on radiologic imaging. Surgery was performed. OUTCOMES: A final diagnosis of microcystic serous cystadenoma of the pancreas without connectivity of MPD was confirmed in both patients. LESSONS: An unnecessary surgery was performed due to atypical radiologic features in which the pancreatic duct seems to be connected to the pancreatic cystic lesion on magnetic resonance imaging, leading to misdiagnosis of SCN as IPMN. Particular attention should be paid to interpretation of clinicoradiologic findings of pancreatic cystic lesions, especially to the decision of surgical intervention. Also, awareness of presence of the atypical radiologic features of SCN may broaden the knowledge base of radiologists. LESSONS: An unnecessary surgery was performed due to atypical radiologic features in which the pancreatic duct seems to be connected to the pancreatic cystic lesion on magnetic resonance imaging, leading to misdiagnosis of SCN as IPMN. Particular attention should be paid to interpretation of clinicoradiologic findings of pancreatic cystic lesions, especially to the decision of surgical intervention. Also, awareness of presence of the atypical radiologic features of SCN may broaden the knowledge base of radiologists.

Extragastrointestinal stromal tumour of the transverse mesocolon mimicking giant ovarian cystic neoplasm.

Gastrointestinal stromal tumours (GISTs) are mesenchymal tumours which are most commonly found along the gastrointestinal tract. They are more rarely found in an extragastrointestinal location and typically present late due to only vague symptoms from mass effect. There are very few case reports of GIST arising within the transverse mesocolon. We report a case of a large cystic transverse mesocolic GIST which preoperative imaging concluded was likely of ovarian origin. This resulted in an abrupt change in the surgical management intraoperatively, but fortunately, an R0 resection was still achieved. This serves as an important lesson to keep the differential diagnosis broad when dealing with large cystic abdominal masses. The tumour was found to be KIT wild type, with a platelet-derived growth factor receptor alpha D842V mutation identified, conferring intrinsic resistance to imatinib.

Identification of high-risk features in mucinous cystic neoplasms of the pancreas.

BACKGROUND: Mucinous cystic neoplasms of the pancreas are uncommon tumors that have the potential of becoming cancer. There is no consensus regarding the high-risk features of these tumors. Our study aimed to identify the preoperative demographic, clinical, or radiologic factors that can predict the presence of high-grade dysplasia or invasive carcinoma in mucinous cystic neoplasms of the pancreas. METHODS: We identified 157 patients who underwent resection and fulfilled the pathologic criteria for mucinous cystic neoplasms of the pancreas in a prospectively maintained database spanning 3 decades (1990-2020). Multivariable logistic regression was used to identify predictors of high-grade dysplasia or invasive carcinoma in mucinous cystic neoplasms of the pancreas. RESULTS: The rate of high-grade dysplasia or invasive carcinoma was 11%. Tumor size ≥4 cm (P < .001), mural nodularity (P = .04), and a serum CA 19-9 level >37 U/mL (P < .001) were associated with high-grade dysplasia or invasive carcinoma. In the multivariable analysis, tumor size ≥4 cm (odds ratio 16.9, 95% confidence interval 2.04-140, P = .009) and a CA 19-9 level >37 U/mL (odds ratio 5.68, 95% confidence interval 1.52-21.3, P = .010) were predictors of high-grade dysplasia or invasive carcinoma. There were no tumors with high-grade dysplasia or invasive carcinoma in patients with tumor size <4 cm in the absence of an elevated CA 19-9 or mural nodularity. CONCLUSION: Tumors with a size ≥4 cm and/or a high CA 19-9 level should be considered for prompt surgical resection. Conversely, tumors <4 cm with no other high-risk features have a negligible risk for high-grade dysplasia or invasive carcinoma and may benefit from nonoperative surveillance. Mural nodularity is an additional suspicious feature. These findings may contribute to future guidelines.