Small serotonin-positive pancreatic endocrine tumors caused obstruction of the main pancreatic duct

Figure 1 No tumor was detected by endoscopic ultrasonography, computed tomography and magnetic resonance imaging. The diameter of the main pancreatic duct was > 20 mm at the body. A: Ultrasonography; B: Endoscopic ultrasonography; C: Computed tomography; D: Magnetic resonance cholangiopancreatography; E: Endoscopic retrograde pancreatography.

Figure 2 Pathological findings (hematoxylin/eosin staining). A: A 5 mm × 3 mm tumor was detected (arrows); B: Fibrosis was present around the main pancreatic duct (arrow), and it seemed to cause stricture.

Figure 3 Immunohistochemical staining was positive for chromogranin A, synaptophysin and serotonin. A: Hematoxylin/eosin staining; B: Chromogranin A; C: Serotonin. Ki-67 labeling index was less than 1%.

Figure 4 Dilation of the main pancreatic duct. Endoscopic ultrasonography was demonstrated presence of a small pancreatic tumor. A: Ultrasonography; B: Magnetic resonance imaging; C: Magnetic resonance cholangiopancreatography; D: Endoscopic retrograde pancreatography.

Figure 5 Pathological findings (hematoxylin and eosin staining) and immunohistochemical staining. A: A 4 mm × 5 mm tumor was detected (arrows); B: Chromogranin A; C: Serotonin. MPD: Main pancreatic duct.