A 45-year-old woman comes to the physician due to several months of progressively worsening watery diarrhea. She has cramps in her leg muscles and feels very dehydrated. She also has mild abdominal discomfort and describes her stools as tea colored. The patient has episodic flushing in her face. She follows a normal diet and has no fever or weight loss. There has been no recent travel to unusual places. The patient smokes 1-2 cigarettes a day and drinks socially. Her temperature is 36.8 C (98.1 F), blood pressure is 108/64 mm Hg, pulse is 118/min, and respirations are 18/min. Abdominal examination shows a nontender abdomen with normoactive bowel sounds. Laboratory results are as follows. A CT scan of the abdomen shows a 3-cm mass in the pancreatic tail. Which of the following is the most likely diagnosis?

Question

A 45-year-old woman comes to the physician due to several months of progressively worsening watery diarrhea.  She has cramps in her leg muscles and feels very dehydrated.  She also has mild abdominal discomfort and describes her stools as tea colored.  The patient has episodic flushing in her face.  She follows a normal diet and has no fever or weight loss.  There has been no recent travel to unusual places.  The patient smokes 1-2 cigarettes a day and drinks socially.  Her temperature is 36.8 C (98.1 F), blood pressure is 108/64 mm Hg, pulse is 118/min, and respirations are 18/min.  Abdominal examination shows a nontender abdomen with normoactive bowel sounds.  Laboratory results are as follows.  A CT scan of the abdomen shows a 3-cm mass in the pancreatic tail.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec25c8_d3ce_1d78_bc81_63a5bdd65e10_MD0003_00 This patient's presentation suggests VIPoma, a rare tumor affecting the pancreatic cells that produce vasoactive intestinal peptide (VIP). Most affected adults are between ages 30-50. VIP binds to intestinal epithelial cells to increase fluid and electrolyte secretion in the intestinal lumen. Most patients develop VIPoma syndrome (pancreatic cholera) with watery diarrhea (can be tea colored and odorless), muscle weakness/cramps (due to hypokalemia), and hypo- or achlorhydria (due to decreased gastric acid secretion). The stool volume can be greater than 3L/day, leading to significant volume depletion. Other findings include facial flushing, lethargy, nausea, vomiting, abdominal pain, and weight loss. Patients can also have coexisting hyperparathyroidism as part of multiple endocrine neoplasia (MEN) syndrome. Laboratory studies usually show hypokalemia due to increased intestinal potassium secretion. Other possible findings include hypercalcemia (due to increased bone resorption) and hyperglycemia (due to increased glycogenolysis). Stool studies are consistent with secretory diarrhea and show increased stool sodium and stool osmolal gap <50 mOsm/kg. A VIP level >75 pg/mL confirms VIPoma diagnosis. Abdominal imaging (cross-sectional triple-phase abdominal CT or MRI) can localize the tumor in the pancreas. Nearly 75% of VIPomas are in the pancreatic tail and 60%-80% have metastasized to the liver by the time of diagnosis. Treatment involves intravenous volume repletion, octreotide to decrease diarrhea, and possible hepatic resection in patients with metastasis to the liver. (Choice A) Carcinoid syndrome can cause flushing, diarrhea, and bronchospasm. However, nearly 70%-80% of carcinoid tumors occur in the small intestine and do not usually involve the pancreas. (Choice B) Gastrinomas can occur in the pancreas and cause diarrhea. However, they cause increased gastrin release with multiple gastric ulcers and dyspepsia (Zollinger-Ellison syndrome). In addition, they are not usually associated with facial flushing (seen in this patient). (Choice C) Pancreatic adenocarcinoma involving the tail typically presents with abdominal and/or back pain, though it may occasionally cause steatorrhea, jaundice, or weight loss. The severe watery diarrhea with significant hypokalemia is more consistent with a neuroendocrine tumor like VIPoma. (Choice D) Systemic mastocytosis involving the gastrointestinal tract can cause steatorrhea, hepatomegaly, and peptic ulcer disease. Patients also usually develop skin symptoms including pruritus, facial flushing, and urticaria. However, mastocytosis would not cause the pancreatic mass seen in this patient. Educational objective: VIPoma is a rare tumor affecting the pancreatic cells that produce vasoactive intestinal peptide (VIP). Most patients develop VIPoma syndrome (pancreatic cholera) with watery diarrhea, muscle weakness/cramps (due to hypokalemia), and hypo- or achlorhydria (due to decreased gastric acid secretion). Stool studies are consistent with secretory diarrhea; a VIP level >75 pg/mL confirms VIPoma diagnosis. References: Pancreatic VIPomas: subject review and one institutional experience (http://www.ncbi.nlm.nih.gov/pubmed/17510774)

A 45-Year-Old Woman Comes to the Physician Due to Several