Association of Chronic Pancreatitis and Malignant Main Duct IPMN: A Rare but Difficult Clinical Problem

Misdiagnosis of pancreatic intraductal papillary mucinous neoplasms and the challenge of mimicking lesions: imaging diagnosis and differentiation strategies

The rising prevalence of pancreatic cystic lesions (PCLs), particularly intraductal papillary neoplasms (IPMNs), has been attributed to increased utilization of advanced imaging techniques. Incidental detection of PCLs is frequent in abdominal CT and MRI scans, with IPMNs representing a significant portion of these lesions. Surveillance of IPMNs is recommended due to their malignant potential; however, their overlapping imaging features with benign entities can lead to misdiagnosis, overtreatment, and overutilization of healthcare resources. This paper aims to highlight and differentiate lesions often mistaken for IPMNs, providing insight into their imaging characteristics, diagnostic challenges, and distinctive features while highlighting the incidence of wrong diagnosis for these lesions. These lesions include serous cystadenomas, cystic pancreatic neuroendocrine tumors, mucinous cystic neoplasms, lymphoepithelial cysts, duodenal diverticula, pancreatic schwannomas, chronic pancreatitis, retention cysts, intrapancreatic accessory spleens, pancreatic lipomas, choledochal cysts, and others. Utilizing various imaging modalities, including contrast-enhanced CT, MRI, and EUS, alongside histological and molecular analyses, can aid in accurate diagnosis and appropriate management. Understanding these mimicry scenarios is crucial to avoid unnecessary surveillance, interventions, and the burden they place on both patients and healthcare systems. Improved recognition of these lesions can lead to better patient outcomes and resource allocation.

Different Etiologies of Dilated Pancreatic Duct Based on Endoscopic Ultrasonography Findings

Background

Pancreatic duct (PD) dilation could be presented in both benign and malignant diseases. Endoscopic ultrasonography (EUS) is a sensitive modality that provides both structural assessment and tissue sampling. This study aims to explore the importance of PD dilation as a potential indicator related to various pancreatobiliary pathologies identified via EUS.

Methods

Among 3109 subjects who underwent EUS, 599 had evidence of dilated PD and met the inclusion criteria of this retrospective study. Also, the patients underwent EUS fine needle aspiration (EUS-FNA) to evaluate the etiology when required. All data were extracted from patients' medical records to perform statistical analysis.

Results

The study sample revealed 64% being male with a median age was 65-years. Pancreatic adenocarcinoma was the most common etiology diagnosed in 236 patients (39.4%), followed by sphincter of Oddi dysfunction (SOD) in 13% of subjects. Ampullary carcinoma, common bile duct stone, and cholangiocarcinoma were found at 9.5%, 8.8%, and 6.8%, respectively. Abdominal pain was the most common symptom seen in 440 (73.4%) patients. Opium consumption was reported in 170 (28.4%) subjects. Opium consumption was significantly more prevalent in patients with SOD (P<0.05).

Conclusion

We suggest that PD dilation could be associated with a wide range of pancreaticobiliary pathologies, especially pancreatic neoplasms. In this regard, PD dilation should be considered as a crucial indicator of pancreatic neoplasm despite it may be associated with no clear etiologies.

Pancreatic Incidentaloma

Pancreatic incidentalomas (PIs) represent a clinical entity increasingly recognized due to advances in and easier access to imaging techniques. By definition, PIs should be detected during abdominal imaging performed for indications other than a pancreatic disease. They range from small cysts to invasive cancer. The incidental diagnosis of pancreatic cancer can contribute to early diagnosis and treatment. On the other hand, inadequate management of PIs may result in overtreatment and unneeded morbidity. Therefore, there is a strong need to evaluate the nature and clinical features of individual PIs. In this review, we summarize the major characteristics related to PIs and present suggestions for their management.

The Dilemma of the Dilated Main Pancreatic Duct in the Distal Pancreatic Remnant After Proximal Pancreatectomy for IPMN

OBJECTIVE(S)

A dilated main pancreatic duct in the distal remnant after proximal pancreatectomy for intraductal papillary mucinous neoplasms (IPMN) poses a diagnostic dilemma. We sought to determine parameters predictive of remnant main-duct IPMN and malignancy during surveillance.

METHODS

Three hundred seventeen patients underwent proximal pancreatectomy for IPMN (Indiana University, 1991-2016). Main-duct dilation included those ≥ 5 mm or "dilated" on radiographic reports. Statistics compared groups using Student's T/Mann-Whitney U tests for continuous variables or chi-square/Fisher's exact test for categorical variables with P < 0.05 considered significant.

RESULTS

High-grade/invasive IPMN or adenocarcinoma at proximal pancreatectomy predicted malignant outcomes (100.0% malignant outcomes; P < 0.001) in remnant surveillance. Low/moderate-grade lesions revealed benign outcomes at last surveillance regardless of duct diameter. Twenty of 21 patients undergoing distal remnant reoperation had a dilated main duct. Seven had main-duct IPMN on remnant pathology; these patients had greater mean maximum main-duct diameter prior to reoperation (9.5 vs 6.2 mm, P = 0.072), but this did not reach statistical significance. Several features showed high sensitivity/specificity for remnant main-duct IPMN.

CONCLUSIONS

Remnant main-duct dilation after proximal pancreatectomy for IPMN remains a diagnostic dilemma. Several parameters show a promise in accurately diagnosing main-duct IPMN in the remnant.

Per Oral Pancreatoscopy Identification of Main-duct Intraductal Papillary Mucinous Neoplasms and Concomitant Pancreatic Duct Stones: Not Mutually Exclusive

OBJECTIVES

Per oral pancreatoscopy (POP) assists in the evaluation and treatment of select benign and neoplastic pancreatic disorders including main-duct intraductal papillary mucinous neoplasm (MD-IPMN). Although pancreatic duct stones are classically thought of as pathognomonic for chronic pancreatitis, its co-occurrence with MD-IPMN as identified via POP may help identify an alternative etiology for presumed idiopathic chronic pancreatitis.

METHODS

This was a multicenter retrospective case series of patients found to have pancreatic duct stones with concomitant MD-IPMN by POP.

RESULTS

Thirteen patients with presumed idiopathic chronic calcific pancreatitis were found on POP to have both pancreatic duct stones and MD-IPMN. All patients had a dilated pancreatic duct, and most (92.3%) were symptomatic.

CONCLUSIONS

Per-oral pancreatoscopy may identify MD-IPMN as an etiology for patients with presumed idiopathic chronic calcific pancreatitis and associated dilated pancreatic duct. Larger prospective studies are needed to validate these findings.