Case Report
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Oct 7, 2017; 23(37): 6911-6919
Published online Oct 7, 2017. doi: 10.3748/wjg.v23.i37.6911
Rupture of small cystic pancreatic neuroendocrine tumor with many microtumors
Ryota Sagami, Hidefumi Nishikiori, Shoichiro Ikuyama, Kazunari Murakami
Ryota Sagami, Hidefumi Nishikiori, Department of Gastroenterology, Oita San-ai Medical Center, Oita 8701151, Japan
Shoichiro Ikuyama, Department of Internal Medicine and Clinical Investigation, Oita San-ai Medical Center, Oita 8701151, Japan
Kazunari Murakami, Department of Gastroenterology, Faculty of Medicine, Oita University, Yuhu 8795503, Japan
Author contributions: Sagami R, Nishikiori H and Ikuyama S designed the study and wrote the manuscript; Sagami R and Nishikiori H collected and analyzed the patient’s clinical data; and Murakami K made critical revisions to the article for important intellectual content.
Institutional review board statement: The Ethics Committee of Oita San-ai Medical Center approved this clinical study and the publication of this case report.
Informed consent statement: The patient involved in this case report authorized the disclosure of her protected health information for academic purposes.
Conflict-of-interest statement: All authors indicate that they have no financial interests or potential conflicts of interest to declare.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Correspondence to: Ryota Sagami, MD, Department of Gastroenterology, Oita San-ai Medical Center, Oita 8701151, Japan.
Telephone: +81-975-411311 Fax: +81-975-415218
Received: June 9, 2017
Peer-review started: June 10, 2017
First decision: July 13, 2017
Revised: July 26, 2017
Accepted: August 15, 2017
Article in press: August 15, 2017
Published online: October 7, 2017

Pancreatic neuroendocrine tumors (pNETs) are particularly rare. The various forms of PNETs, such as cystic degeneration, make differentiation from other similar pancreatic lesions difficult. We can detect small lesions by endoscopic ultrasound (EUS) and obtain preoperative pathological diagnosis by EUS-guided fine needle aspiration (FNA). We describe, here, an interesting case of pNET in a 42-year-old woman with no family history. Computed tomography and magnetic resonance imaging revealed an 18 mm × 17 mm cystic lesion with a nodule in the pancreatic tail. Two microtumors about 7 mm in diameter in the pancreatic body detected only by EUS, cystic rim and nodules all showed similar enhancement on contrast-harmonic EUS. Preoperative EUS-FNA of the microtumor was performed, diagnosing multiple pNETs. Macroscopic examination of the resected pancreatic body and tail showed that the cystic lesion had morphologically changed to a 13-mm main nodule, and 11 new microtumors (diameter 1-3 mm). Microscopically, all microtumors represented pNETs. From the findings of a broken peripheral rim on the main lesion with fibrosis, rupture of the cystic pNET was suspected. Postoperatively, pituitary adenoma and parathyroid adenoma were detected. The final diagnosis was multiple grade 1 pNETs with multiple endocrine neoplasia type 1. To the best of our knowledge, no case of spontaneous rupture of a cystic pNET has previously been reported in the English literature. Therefore, this case of very rare pNET with various morphological changes is reported.

Keywords: Rupture, Cystic pancreatic neuroendocrine tumor, MEN1, NET, Microtumor

Core tip: Cystic or multiple pancreatic neuroendocrine tumors (pNETs) are very rare. This report describes a case of cystic pNET with multiple small tumors diagnosed from endoscopic ultrasonography (EUS) alone. Preoperative diagnosis was able to be obtained by EUS-guided fine needle aspiration biopsy. Postoperatively, 11 other micro-pNETs with multiple endocrine neoplasia type 1 were detected and cystic pNET morphologically changed to a small nodule because of suspected spontaneous rupture. Spontaneous rupture of cystic pNET has not been reported previously in the English literature.