Life-Threatening VIPoma Crisis in an Immunocompromised Patient

Background: Vasoactive intestinal peptide-secreting tumors (VIPoma) are rare neuroendocrine tumors (NETs) that present with a triad of profuse watery diarrhea, hypokalemia, and achlorhydria. The resulting renal impairment, electrolytes and acid-base imbalances pose a high risk of morbidity and mortality. We describe a case of life-threatening VIPoma crisis in an immunocompromised patient. Clinical Case: A 64-year-old man was intubated after he was brought in unconscious with tachypnea. Upon review, he had experienced persistent watery diarrhea for the past 6 months, with a weight loss of 18 kg. He had severe hypokalemia (potassium 1.9 mmol/L, n= 3.5-5.0), metabolic acidosis (blood gases pH 6.927, bicarbonate 4.8 mmol/L, base excess -25.9 mmol/L), and acute kidney injury (urea 47.9 mmol/L, creatinine 980umol/L). He continued to have electrolyte imbalances and acidosis due to persistent diarrhea, despite hydration and dialysis support. His biohazard screening results were positive for human immunodeficiency virus (HIV), with a CD4 count of 101 cells/µl. He was given courses of antibiotics for treating pathogenic infections; however, his septic workups were negative for infection, including HIV-related opportunistic infections. Later, pancreatic CT revealed a well-defined heterogeneously enhancing pancreatic head mass, size 6.8x5.2x7.5 cm. Further laboratory investigations confirmed the diagnosis of VIPoma, with elevated VIP levels (1600 pg/ml, n < 75). Eventually, subcutaneous octreotide was started, with resolution of the diarrhea and normalization of his electrolytes and renal function. After a 6-week hospital stay, he was discharged well with monthly octreotide and initiated on antiretroviral therapy (ART). After 3 months of ART, his CD4 count improved, and he remained diarrhea-free with octreotide. He is scheduled for tumor debulking surgery. Conclusion:This case highlights the importance of having a clinical suspicion of NETs, especially in immunocompromised patients. Further investigations and imaging studies to rule out noninfectious pathologies should be considered in patients who respond poorly to standard therapy. In VIPoma, somatostatin analog is an antisecretory treatment and it is highly effective for controlling diarrhea. High-dose octreotide up to 1500 µg/day has previously been studied for treatment of refractory diarrhoea in the setting of HIV infection² and it has been found to be helpful in reducing stool volume and frequency. Lastly, delays in the diagnosis and treatment of VIPoma in immunocompromised patients can be fatal. References1/ Hoffland J., Kaltsas G., de Herder W. Advances in the Diagnosis and Management of Well-Differentiated Neuroendocrine Neoplasms. Endocrine Reviews, Volume 41, Issue 2, April 2020, Pages 371-403.2/ Farthing MJ. Octreotide in the treatment of refractory diarrhoea and intestinal fistulae. Gut 1994;35:S5-10.