Clinical Case Summary

A 72-year-old man with a 49-year history of ulcerative colitis (UC), characterized as pancolitis and steroid-dependent, underwent routine surveillance colonoscopy. A congested, ulcerated mass was found in the recto-anal region, with no signs of active colitis in the rest of the colon.
From 2000–2012, he was treated with infliximab, discontinued due to secondary failure, followed by azathioprine (2012–2017), which was stopped due to leukopenia. Since then, he has been on vedolizumab. His medical history also includes hypertension and previous tobacco use.
The patient had been in clinical and biochemical remission for the last two years. Given his long-standing UC and the resection of a lateral spreading tumor (LST) via mucosectomy in 2019 showing hyperplastic mucosa with a focus of low-grade dysplasia, he has been under annual endoscopic surveillance.
At the current exam, a large exophytic, ulcerated mass with superficial necrosis and fibrin (Kudo IV) was seen in the recto-anal region, occupying approximately 1/6 of the luminal circumference and bleeding spontaneously.
Histology revealed a poorly differentiated neuroendocrine carcinoma (NEC) with a high proliferative index (Ki-67: 60%). Staging workup, including CT, pelvic MRI, and endoscopic ultrasound, identified a suspicious regional lymph node, that was confirmed by FDG-PET to be metabolically active.
After multidisciplinary discussion, the decision was made to start systemic chemotherapy without delay. If the patient responds, a total proctocolectomy with permanent ileostomy will be considered.
This case is notable for the rarity of recto-anal NECs, especially in UC patients. Their poor prognosis and unclear association with long-term UC or immunosuppressive treatment complicate management and raise important clinical questions.

References

Images that will be uploaded are: endoscopic findings of the colonic mass, histological specimens of the NEC, radiologic findings (PET)

Introduction

Endoscopic retrograde cholangiopancreatography (ERCP) is recognized as a foundational procedure within the realm of interventional gastroenterology. Nevertheless, a significant amount of hands-on experience is required to achieve proficiency in this procedure, particularly with regard to the performance of sophisticated therapeutic maneuvers. Access to authentic training cases remains limited, while the use of cadaveric or live animal models presents distinct ethical, logistical and financial challenges (1). The advent of 3D printing technology paved the way for the development of advanced medical simulators. This study utilized computer-aided design and fused deposition modeling techniques to engineer an ERCP simulator that is both anatomically accurate and enables the training of trainee physicians in the intricate procedures of their chosen discipline (2). The simulator's modular design allows it to replicate a spectrum of papillary conditions, enabling targeted training in anatomies that are resistant to cannulation, as well as high-risk procedures like precut sphincterotomy and fistulotomy.

Aims & Methods

The design process for the ERCP simulator employed accessible parametric modeling software. Fabrication of the primary structural components, including the pancreas, the duodenum, and the bile ducts, were undertaken using polylactic acid (PLA) filament, a material that is both widely accessible and economical, thereby ensuring adequate rigidity and durability. The interchangeable papillary components were produced using flexible thermoplastic polyurethane (TPU) 95A filament, selected for its elasticity and capacity to be readily incised during procedures such as endoscopic sphincterotomy (EST). This allowed for easy exchangeability and facilitated the acquisition of skills by novice endoscopists. This process were selected on the basis of accessibility, user-friendly interface and cost-effectiveness, enabling replication in diverse settings. The biliary and pancreatic ductal lumens were meticulously calibrated to represent a range of procedural difficulty, with internal diameters that closely mirrored real anatomical variations.

Results

The simulator exhibited a high degree of anatomical and biomechanical fidelity, featuring a structurally stable duodenal framework and a flexible papillary interface. The simulator accurately reproduced tactile feedback experienced by gastroenterologists during ERCP, thereby validating its efficacy as a training tool. Furthermore, the simulator was enabled meticulous rehearsal of EST through sphincterotomy incisions and facilitated fistulotomy simulation using an elastomeric papilla structure. The simulator's design is both cost-effective and easily replicable, making it a valuable asset for continuing education and training in this field (3,4).

Conclusion

The ERCP simulator, fabricated using 3D printing technology, can be regarded as both technologically advanced and economically efficient for a number of complex procedures. These encompass endoscopic sphincterotomy, precut techniques, fistulotomy and stent placement. The simulator's design, featuring a modular papillary system, was crafted to provide a structured and progressive learning environment for novice users as well as experienced endoscopists. The simulator's cost-effectiveness, ease of scaling up and potential for wide dissemination signify a paradigm shift in ERCP education, facilitating proficiency acquisition in complex interventional endoscopy with greater efficiency and safety. Further investigations are needed for the simulator in ERCP training.

References

1. Lee S, Ahn JY, Han M, Lee GH, Na HK, Jung KW, et al. Efficacy of a three-dimensional-printed training simulator for endoscopic biopsy in the stomach. Gut and liver. 2017;12(2):149.
2. Zhang Y, Chen L, Hu B. Advances of 3D printing in gastroenterology and where it might be going. International Journal of Bioprinting. 2023;9(6):0149.
3. Lee DS, Ahn JY, Lee GH. A newly designed 3-dimensional printer-based gastric hemostasis simulator with two modules for endoscopic trainees (with video). Gut and Liver. 2019;13(4):415.
4. Bundy JJ, Weadock WJ, Chick JFB, Srinivasa RN, Patel N, Johnson E, et al. Three-dimensional printing facilitates creation of a biliary endoscopy phantom for interventional radiology-operated endoscopy training. Current Problems in Diagnostic Radiology. 2019;48(5):456-61.