Diagnosis of Neuroendocrine Tumor of the Pancreas by External Ultrasound-Fine Needle Aspiration Cytology Sampling: Case Report and a Brief Review of the Literature

Pancreatic neuroendocrine tumors (PanNETs) are uncommon pancreatic neoplasms that develop from islet cells. The existing method of preoperative tissue diagnosis and grading is ultrasound-guided fine-needle aspiration of the mass. We present a case of a 42-year-old female who presented with a six-month history of nonspecific epigastric pain and unintentional weight loss. Imaging showed a small pancreatic mass with increased vascularity in the pancreatic tail. Chromogranin A serum levels were elevated. The diagnostic material was not collected according to the standard Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) procedure, but rather via the less common external (abdominal, percutaneous) ultrasound-guided fine-needle aspiration (US-FNA) with rapid onsite evaluation (ROSE). It was well-differentiated, Grade 1 PanNET, and, with immunohistochemistry (IHC), positive for Synaptophysin and Chromogranin A, with low Ki-67 (2%). Laparoscopic distal pancreatectomy, splenectomy, and R0 resection were performed. At 3-year follow-up, she was recurrence-free. The case has shown that external US-FNA has high diagnostic accuracy, especially in facilities with limited EUS expertise, or when the lesion can be approached percutaneously, which has proved useful for good preoperative grading even in small tumors and for leading to definitive curative surgery.