Multiple liver metastases caused by micro-pancreatic primary VIPoma: A case report and literature review

Vasoactive intestinal polypeptide–secreting tumors (VIPomas) are rare, and the liver is the organ most frequently involved in metastasis. In this case report, we describe a rare case of large multiple liver metastases caused by a small primary G2 VIPoma of the pancreas, which was highly likely to be diagnosed as a primary hepatic VIPoma. The patient presented with a 6-month history of watery diarrhea, hypokalemia, weight loss, and liver tumor and underwent partial hepatectomies 2 times in our hospital. It took almost 39 months from the appearance of WDHA symptoms (watery diarrhea, hypokalemia, achlorhydria syndrome) to the discovery of a pancreatic mass and the diagnosis of pancreatic VIPoma. The patient did not experience tumor recurrence or WDHA symptoms after partial pancreatectomy. Our report demonstrates the efficacy and necessity of metastatic tumor resection and basic supportive care for patients. 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) as a systemic examination method to be considered when the location of the primary tumor is unclear. This report provides significant guidance for diagnosing endocrine tumors of unknown origin in the liver. PET/CT and timely follow-up can reduce the incidence of misdiagnosis.