Endoscopically Placed Fiducial Markers Aid in Insulinoma Resection

Abstract

Case: A 47-year-old female presented with hypoglycemia for 1 year. The 72-hour fast was terminated for hypoglycemic symptoms and glucose of 40 mg/dL. Laboratories revealed low insulin level and low–normal C-peptide with elevated proinsulin, suggesting proinsulin-secreting neuroendocrine tumor (NET). Insulinoma is the most common functioning pancreatic NET and presents with symptoms of hypoglycemia. CT was negative for pancreatic mass. Endoscopic ultrasonography (EUS) revealed an 8 × 7 mm midbody pancreatic mass and biopsy confirmed NET. Fiducial markers were placed with EUS guidance to aid intraoperative localization during partial pancreatectomy. Intraoperative fluoroscopy (IOF) and laparoscopic ultrasonography (LUS) localized the peritumoral fiducials. The mass was close to the splenic vessels and nearly abutting the pancreatic duct. A 60-mm laparoscopic stapler was inserted, and the fiducials were used to achieve ≥1 cm surgical margin (video). The total laparoscopic distal pancreatectomy was completed with a spleen-sparing technique. Postoperatively, the hypoglycemia resolved. Discussion: Most NETs are intrapancreatic, 90% are solitary, 90% are <2 cm in diameter, and tumors are found equally throughout the pancreas.1 EUS, utilized in diagnosis and localization in this case, has recognized advantages over other observation techniques. As seen in this study, diagnosis of pancreatic tumors is possible despite negative CT.2 Sensitivity of EUS ranges from 37% to 94% regardless of the functional state of the insulinoma, and is largely dependent on the location of the lesion. EUS is best at detecting tumors in the head and worst at detecting those in the tail of the pancreas.3 EUS has low complication rates and has a relative ease of use with a skilled operator.4 Localization before surgery is desired because most tumors are not palpable at the time of surgery, and type of surgery can be determined based on location.5 Using EUS for preoperative staging of pancreatic tumors has been in practice for several years, although it is usually achieved through tattoos and dyes.6,7 Preoperative localization of pancreatic endocrine tumors with tattoos and dyes has been shown to decrease operative time and blood transfusion requirement.8 Most data regarding localization of pancreatic tumors concern insulinomas, although proinsulinomas have been localized with tattoos.9 Tattoos and dyes have potential complications of absorption into surrounding tissues, peritonitis, infection, and allergic reaction.10 Fiducial markers are radiopaque 3 mm gold particles often endoscopically placed through 22 gauge needle. They are observed with LUS and IOF during resection, and shorten operative time by revealing the location of nonpalpable tumors or tumors that are poorly observed through LUS alone. By shortening operative time, it reduces perioperative complications, reduces need for reoperation, and increases likelihood of an effective outcome.11 Fiducials are superior to ink/tattoos by eliminating imprecise localization from ink absorption into surrounding tissues.12 Reported complications include most common abdominal pain, followed by cholangitis, pancreatitis, minor bleeding, fever, and elevated liver enzymes.13–16 No competing financial interests exist. Runtime of video: 7 mins 48 secs Presented as Poster Abstract at American College of Gastroenterologists Annual Scientific Meeting 2014, Philadelphia.