Published online Oct 7, 2017. doi: 10.3748/wjg.v23.i37.6911
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.
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.