Pancreatic neuroendocrine microadenomatosis presenting as a functional VIPoma

Abstract

Pancreatic microadenomas are benign tumors of neuroendocrine origin less than 5 mm in size. Whereas most microadenomas are non-functional; a few rare functional pancreatic microadenomas have been described in the setting of multiple endocrine neoplasia type one (MEN-1). In this report, we describe a unique case of multiple functional microadenomas of the pancreatic head in a patient who presented with persistent secretory diarrhea, refractory hypokalemia, metabolic acidosis and elevated plasma vasoactive intestinal peptide (VIP) levels. Following extensive serologic, radiographic and endoscopic work up, our patient underwent open pancreaticoduodenectomy with subsequent resolution of diarrheal symptoms and electrolyte abnormalities on postoperative follow up.

Figure 1:

Computed tomography scan of the abdomen and pelvis with intravenous contrast (Omnipaque 350^TM, iohexol, 50 mL). No evidence of pancreatic mass or biliary ductal dilation was identified.

Figure 2:

(a–c) (a and b.) Octreotide scan demonstrating increased activity in the peripancreatic region (6.6 mCi of Indium-111 labeled octreotide). (c) Repeat octreotide scan (6 of Indium-111 labeled octreotide) at 4 months post-resection demonstrated normal distribution of activity in the liver, spleen and urinary system. No other focal area of activity was identified.

Figure 3:

(a–c) Permanent pathology. (a and b) Multiple pancreatic microadenomas scattered throughout the pancreatic head parenchyma. (c) Immunohistochemical stains positive for synaptophysin.