A 10-mm pedunculated
polyp in the gallbladder neck was detected on a follow-up abdominal ultrasound in a 60-year-old man with
chronic hepatitis and
hepatitis B without medication. Six months later, an abdominal ultrasound revealed that the
tumor had enlarged to 12 mm in size. He was asymptomatic and had no abnormalities in other laboratory examinations, including the
tumor markers,
carcinoembryonic antigen and CA19-9. Abdominal ultrasound showed a 12-mm
polyp in the neck of the gallbladder with perfusion and focal thickening of the gallbladder wall. A gallbladder stone was also seen in the fundus. An enhanced computed tomography scan and magnetic resonance imaging revealed a polypoid lesion and gallbladder stone located at the neck of the gallbladder and the fundus, respectively.
Malignancy could not be excluded, and hence, a
laparoscopic cholecystectomy was performed. Pathologically, a pedunculated
polyp (14 × 11 × 15 mm) was observed in the neck of the gallbladder, and the polypoid lesion comprised nests or trabecular growths of clear NET cells in the lamina propria (ENETS: T1N0M0; AJCC: T1aN0M0). Immunohistochemical staining with
synaptophysin,
chromogranin A, and CD56 was confined to the
tumor. The pathological diagnosis was clear cell NET G1 of the gallbladder. Although clear cell NET is often described as a distinct manifestation of
von Hippel-Lindau disease (VHL), the patient had no past medical or family history of VHL. Until his one-and-a-half-year follow-up, the patient was doing well and without any signs of recurrence.
CONCLUSION: We report an extremely rare case of gallbladder clear cell NET G1. When NET G1 is incidentally identified in a gallbladder surgical specimen, clinical information and pathological findings should be considered as references.