A Rare Presentation of Lymph Node Metastasis of VIPoma After Three Years of Resection: A Case Report

Abstract

Vasoactive intestinal peptide-producing tumor of the pancreas (VIPoma) is one of the rarer subtypes of neuroendocrine tumor (NET) of the pancreas. It usually represents intractable diarrhea, weight loss, and electrolyte abnormalities secondary to diarrhea. The most common site of metastasis of VIPoma is the liver. Furthermore, lymph node metastasis (LNM) is rare, and no metachronous LNM with a resectable situation has been reported before. A 60-year-old male patient (height: 181 cm, body weight: 74 kg) with a history of operated pancreatic VIPoma three years ago was referred to our department due to the detection of lymphadenomegaly which was suggestive of lymph node metastasis by routine follow-up computed tomography (CT). Preoperative CT showed a lymph node on the left side of the abdominal aorta and caudal side of the left renal vein with a size of 1 cm. Lymphadenectomy was performed without significant complications and blood loss. This is the first report of metachronous LNM in a patient with operated VIPoma. Although much rarer than solid organ metastasis of VIPoma, LNM in these patients can also be seen synchronously and metachronously. Close follow-up and vigilance are key to preventing recurrence-related morbidity and mortality in these patients.

Keywords: lymph node metastasis; lymphadenectomy; metachronous; pancreatic neuroendocrine tumors; vipoma.

Figure 1. Preoperative images of the metastatic lymph node and anatomical location of the metastatic lymph node.

Figure 1A: CT image of the mass (shown with white arrow). Figure 1B: Somatostatin receptor scintigraphy image of the mass (shown with white arrow). Figure 1C: Metastatic lymph node in the para-aortic station (shown with white arrow). Figure 1D: Gonadal vein, left renal vein, and aorta visible after resection of the metastatic lymph node.

Figure 2. Pathological examination of the metastatic lymph node with hematoxylin and eosin stain and VIP immunohistochemistry.

Figure 2A-2B: Hematoxylin-eosin staining of the lymph node (×40 and ×400). Tumor cells with round nuclear display an organoid growth pattern surrounded by capillaries. Immunohistochemical staining of chromogranin A, synaptophysin, and CD56 are positive, and the tumor shows a Ki-67 of 2%. Figure 2C-2D: VIP immunohistochemical staining (×40 and ×400). Positive staining of VIP is shown. VIP: vasoactive intestinal peptide