Recurrent acute pancreatitis due to a subtle branch-duct type intraductal papillary mucinous neoplasm: A case report

Abstract

BACKGROUND

Recurrent acute pancreatitis (RAP) poses a significant diagnostic challenge, with some cases remaining idiopathic despite extensive workup. Intraductal papillary mucinous neoplasm (IPMN) is a known precursor to pancreatic cancer, and RAP can be its initial clinical manifestation. However, diagnosing small branch-duct type IPMNs (BD-IPMNs) as the cause of RAP remains a clinical challenge, especially when standard imaging is inconclusive.

CASE SUMMARY

We report the case of a 67-year-old female with a two-year history of RAP. Despite extensive investigations, including computed tomography and magnetic resonance imaging, and even a cholecystectomy, the etiology of her pancreatitis remained elusive. The patient continued to experience recurrent episodes. A probable diagnosis was ultimately achieved during her latest admission through endoscopic ultrasound, which identified a minute (3.6 mm × 3.7 mm) BD-IPMN in the uncinate process containing a 3.3 mm hyperechoic mucus plug. Subsequently, endoscopic retrograde cholangiopancreatography with pancreatoscopy confirmed the presence of multiple mucus plugs within the cystic lesion. These were successfully removed, and a pancreatic stent was placed to ensure drainage.

CONCLUSION

Endoscopic ultrasound plays a critical role in the diagnosis of unexplained RAP. BD-IPMN can cause significant clinical symptoms through mucus production and ductal obstruction. Endoscopic retrograde cholangiopancreatography with pancreatoscopy is a valuable tool for diagnosis and immediate therapeutic intervention.

Key Words: Recurrent acute pancreatitis; Branch-duct type intraductal papillary mucinous neoplasm; Endoscopic ultrasound; Mucinous plugs; Pancreatic stent; Case report

Core Tip: We report a case in which endoscopic ultrasound successfully identified a minute branch-duct type intraductal papillary mucinous neoplasm with mucus plugs as the cause of previously unexplained recurrent acute pancreatitis. The diagnosis was confirmed by endoscopic retrograde cholangiopancreatography with pancreatoscopy. This case highlights the critical role of endoscopic ultrasound in the diagnosis of elusive recurrent pancreatitis and provides a valuable reference for its minimally invasive management, which may help improve etiological diagnosis and avoid unnecessary surgery.

INTRODUCTION

Intraductal papillary mucinous neoplasm (IPMN) is a recognized precursor to pancreatic cancer, and recurrent acute pancreatitis (RAP) can be its initial clinical presentation. However, diagnosing small branch-duct IPMNs (BD-IPMNs) as the cause of RAP remains difficult, especially when conventional imaging yields inconclusive results. Distinguishing a subtle BD-IPMN from other etiologies of pancreatitis is challenging, and subtle BD-IPMN can be easily overlooked. We here report a case in which a minute BD-IPMN was identified as the probable source of RAP, and describe the diagnostic work-up, endoscopic management, and clinical outcome.

CASE PRESENTATION

Chief complaints

A 67-year-old female was admitted on November 3, 2025, following 12 hours of epigastric distending pain accompanied by nausea and vomiting.

History of present illness

The patient had been experiencing epigastric distending pain accompanied by nausea and vomiting for 12 hours, without fever, diarrhea, or significant weight loss or gain. Serum amylase was markedly elevated at 1866 U/L, confirming acute pancreatitis (AP). This episode marked the latest in a series of RAP episodes dating back to September 2023, for which the initial etiology was undetermined.

History of past illness

After her first episode in September 2023, contrast-enhanced computed tomography had raised suspicion for a neoplasm in the uncinate process. Subsequent magnetic resonance imaging (MRI) in February 2024 suggested a possible IPMN (Figure 1). An episode in March 2025 led to a laparoscopic cholecystectomy due to gallstones and cholecystitis was detected during screening. Laparoscopic cholecystectomy was performed to reduce the recurrence of AP, but pancreatitis recurred three months post-operatively. Magnetic resonance cholangiopancreatography in July 2025 indicated a possible small cystic shadow, and follow-up imaging in October 2025 post-cholecystectomy was inconclusive. The timeline of the patient’s previous pancreatitis history is presented in Figure 2. Her past surgical history included a mediastinal tumor resection via mediastinoscopy and thoracoscopy in June 2023 and a prior cesarean section. She had no other relevant medical history.

Figure 1 An enhanced abdominal magnetic resonance imaging suggested a possible intraductal papillary mucinous neoplasm. Orange arrow: Intraductal papillary mucinous neoplasm.

Figure 2 Timeline of the patient’s previous pancreatitis history. AP: Acute pancreatitis; LC: Laparoscopic cholecystectomy; EUS: Endoscopic ultrasound.

Personal and family history

The patient had no history of smoking or drinking, and no history of taking special medications. The patient had no other personal or family history.

Physical examination

Upon admission, her vital signs were temperature 36.4 °C, pulse rate 98 beats/minute, respiratory rate 16 breaths/minute, and blood pressure 112/81 mmHg. Physical examination revealed tenderness in the upper abdomen without rebound tenderness or guarding. An old surgical scar was visible below the umbilicus. The abdomen was flat and soft. The liver and spleen were non-palpable, and no abdominal masses were detected. There was no obvious jaundice of the skin or sclera, and no significantly enlarged superficial lymph nodes were palpated. Examination of the heart and lungs revealed no abnormalities.

Laboratory examinations

Serum amylase was markedly elevated at 1866 U/L. Other routine laboratory tests including triglyceride and blood calcium, autoimmune markers (immunoglobulin G4, antinuclear antibody), and tumor markers (cancer antigen 199, carcinoembryonic antigen, etc.) were within normal limits.

Imaging examinations

Given the recurrent nature and unclear cause of AP, endoscopic ultrasound (EUS) was performed on November 11, 2025. The EUS revealed a small cystic lesion (3.6 mm × 3.7 mm) in the uncinate process that was clearly communicating with a branch duct, confirming the diagnosis of a branch-duct type IPMN (BD-IPMN). It also revealed a distinct, roundish and hyperechoic structure measuring approximately 3.3 mm within the duct and possibly causing the dilation of the distal duct in the pancreatic body and tail to 4.4 mm (Figure 3A and B). The cystic lesion showed no mural nodule or cyst wall thickening. This was confirmed by endoscopic retrograde cholangiopancreatography (ERCP) using a cholangioscope (SpyGlass DS) for direct endoscopic examination of the pancreatic duct. The pancreatoscopy passed through the main pancreatic duct, entered the branch pancreatic duct and dilated cystic cavity, directly revealing multiple white, block-like, and mobile mucus plugs inside the branch pancreatic ducts and the cavity (Figure 3C-E). Based on the above evidences, the BD-IPMN and its secreted mucin were the most likely cause of the patient’s recurrent pancreatitis.

Figure 3 Representative images of branch-duct type intraductal papillary mucinous neoplasm and its mucous plug. A and B: Endoscopic ultrasound revealed a distinct, roundish and hyperechoic structure causing the distal pancreatic duct to expand; C-E: Pancreatoscopy visualized multiple mucus plugs.

FINAL DIAGNOSIS

The patient was diagnosed with mild AP based on symptoms, signs and laboratory tests. Considering the results of EUS, ERCP, pancreatoscopy and previous imaging examinations, after ruling out microlithiasis, alcohol use, hypertriglyceridemia, hypercalcemia, drug-related pancreatitis, autoimmune pancreatitis or other etiologies, we hypothesized that the small BD-IPMN was ultimately considered to be the most likely cause of the patient’s RAP.

TREATMENT

Under direct visualization of the pancreatic scopes during ERCP, the mucus plugs were carefully removed from the branch duct by flushing and aspiration with normal saline, thereby relieving the obstruction. A 5-French, 5-cm plastic pancreatic stent was placed to ensure drainage and to facilitate the removal of any remaining or newly formed mucus. During the hospital stay, symptomatic supportive treatments such as acid suppression, enzyme inhibition, and fluid replacement were provided, and the patient's symptoms were subsequently relieved.

OUTCOME AND FOLLOW-UP

The patient was discharged in good condition. A close outpatient follow-up plan was established to monitor for recurrence of symptoms and to determine the time for stent removal or replacement. No recurrence has been detected to date.

DISCUSSION

This case provides several critical insights for clinicians in dealing with RAP issues. First and foremost, it indicates that even a sub-centimeter BD-IPMN can be a potential reason for RAP through the mechanism of mucinous plugging and intermittent pancreatic duct obstruction. With the widespread application of medical imaging technology, the detection rate of IPMN is increasing. The current guideline consensus classifies obstructive jaundice, enhanced wall nodules, main pancreatic duct (MPD) dilation ≥ 10 mm, and cytological abnormalities as “high-risk signs”; while cyst diameter ≥ 3 cm, thickened cyst wall, and MPD diameter 5~9.9 mm as “cautious features”[1]. In addition to imaging methods such as computed tomography (CT) and MRI, techniques like EUS and ERCP are playing an increasingly crucial role in the assessment and management of IPMN. Although CT/MRI has a relatively high recognition rate for pancreatic cystic lesion features, its accuracy in differentiating between cystic pancreatic masses is only 57%; furthermore, for small cystic lesions with a diameter of less than 1 cm, the diagnosis by CT/MRI has obvious limitations[2]. In contrast, EUS offers the advantages of close proximity, high resolution, and real-time imaging, enables a detailed morphologic evaluation of pancreatic cystic lesions by clearly delineating internal structures such as intracystic septa and mural nodules, while also enabling accurate determination of whether the cyst communicates with the pancreatic duct. Ohno et al[3] discovered that based on the pathological diagnosis, the preoperative EUS examination had a diagnostic sensitivity of 97.6% for IPMN. EUS, along with complementary techniques including contrast-enhanced EUS, contrast-enhanced harmonic EUS[4], EUS guided fine needle aspiration/biopsy[5,6], EUS guided needle based confocal laser endomicroscopy[7], EUS guided through the needle biopsy[8], ERCP, and pancreatoscopy[9], provide substantial value in stratifying malignant risk in IPMN, supporting real time diagnosis, and guiding clinical management decisions. The traditional treatment for IPMN mainly relies on surgical resection, but this approach carries a high risk of complications. However, emerging non-surgical treatment methods, such as EUS guided ablation techniques such as radiofrequency ablation[10], as well as chemical ablation using ethanol or a combination of ethanol and paclitaxel[11], offer minimally invasive alternatives. The efficacy and limitations of these methods are increasingly being confirmed. Additionally, endoscopic sphincterotomy of the pancreatic duct during ERCP can effectively alleviate obstructive symptoms[12], has been proven to reduce the recurrence of pancreatitis and improve patients' quality of life. However, the role of pancreatic duct stents in preventing the recurrence of pancreatitis caused by IPMN has rarely been reported.

The American Gastroenterological Association clinical practice update strongly supports EUS as the preferred diagnostic method for unexplained RAP[13]. In the present patient, after two years of multiple cross-sectional scans, the characterization of the lesion was difficult to determine. It was the high resolution of EUS that ultimately provided morphological detail. Therefore, EUS is an integral component of the diagnostic algorithm for RAP. In addition, the management of this case also posed considerable challenges. ERCP is generally reserved for therapeutic intervention rather than primary diagnosis in RAP due to the risk of inducing pancreatitis[14]. However, ERCP and pancreatoscopy played a crucial role in observing and removing the mucus plug in this case. The subsequent clearance of the plugs under direct visualization of pancreatoscopy during ERCP, followed by pancreatic stent placement directly addressed the obstruction and was essential for the patient's immediate clinical recovery. Notably, while mucin plugs from BD-IPMN obstructing the pancreatic duct were considered the most probable cause of this patient’s RAP, sphincter dysfunction or idiopathic RAP remain potential etiologies that cannot be entirely excluded. During future follow-up, we need to continuously rule out other causes.

The long-term treatment of this patient remains controversial. Although the direct cause of obstruction was removed, the IPMN still exists and will likely continue secreting mucin, posing a risk for future episodes of pancreatitis when the stent is removed. Surgical resection, such as a pancreaticoduodenectomy, would be curative but is associated with substantial morbidity and mortality, especially for a small, benign-appearing BD-IPMN in the pancreatic head. A more limited local resection or removal surgeries carry a high risk of pancreatic fistula. Therefore, a less invasive, endoscopy-based long-term strategy is highly desirable. Options for future management could include performing a pancreatic sphincterotomy upon stent removal to facilitate spontaneous passage of small mucus plugs. Another emerging and promising alternative is EUS-guided RFA or other chemical ablative techniques to destroy the cystic lesion, which could potentially eliminate the source of mucin production without major surgery. The European Society of Gastrointestinal Endoscopy guidelines acknowledge the expanding role of therapeutic EUS for various pancreatic conditions, and such novel approaches may become a viable option for patients like this in the future[15]. Long-term endoscopic monitoring is another crucial but challenging aspect in the treatment process. Finally, we admit that the long-term risk of tumor recurrence or progression of pancreatic ductal intraductal mucinous tumors remains unclear[16]. Moreover, the decision not to undergo surgery is based on individual risk-benefit assessment, which may not be applicable to all patients.

CONCLUSION

This report highlights that RAP caused by subtle BD-IPMN is easily overlooked in clinical practice. To prevent missed diagnosis or misdiagnosis, timely and advanced imaging including EUS and ERCP should be performed when necessary. This case demonstrates that even a subtle BD-IPMN may cause significant clinical symptoms through mucus production and ductal obstruction. ERCP with pancreatoscopy served as a valuable tool for diagnosis and immediate therapeutic intervention, providing a minimally invasive approach for managing this challenging condition. The patient still requires long-term follow-up observation and re-examination, and in case of necessity, endoscopic intervention treatment should be performed again, and other causes leading to RAP should be continuously sought.