7537 Composite Pheochromocytoma-Ganglioneuroma Secreting Vasoactive Intestinal Peptide: A Case Report

Abstract Disclosure: B. Brochu: None. Y. Collin: None. R. Temmar: None. F. Bernier: None. K. Dandurand: None. M. St-Jean: None. M. Massicotte: None. Background: Composite pheochromocytoma-ganglioneuroma is a rare tumor combining features of both pheochromocytoma/paraganglioma (PPGL) and neurogenic tumors. Cosecretion of vasoactive intestinal peptide (VIP) is even less common and highlights the diverse secretory potential of these tumors. Clinical Case: An 80-year-old woman presented with severe chronic diarrhea that had been progressively worsening over the past 10 years. The diarrhea was associated with chronic hyponatremia between 128 and 132 mmol/L. She also had mild hypertension, with a mean blood pressure of 145/90 mm Hg. An abdominal CT scan revealed a right adrenal mass of 68 mm x 44 mm x 50 mm with a density of 19 HU without contrast. A 24-hour urinary collection demonstrated normetanephrines (NM) levels at 3.5 times the upper limit of normal. A 68Ga-DOTATATE PET/CT demonstrated significant uptake only in the adrenal mass. Because of the ongoing severe diarrhea, that is unusual in the context of NM secreting PPGL, serum VIP level was measured and came back at nearly three times the upper limit of normal. A provisional diagnosis of pheochromocytoma with VIP and catecholamines cosecretion was made and surgical resection by laparotomy was performed without complication. Pathology demonstrated a composite tumor combining a pheochromocytoma and a ganglioneuroma, with a Pheochromocytoma of the Adrenal gland Scaled Score (PASS) score of 3. Tumor immunohistochemical staining was positive for VIP in both pheochromocytoma and ganglioneuroma cells. After surgery, diarrhea and hyponatremia resolved and blood pressure normalized. Conclusion: This is one of the very rare cases described in the current literature of a composite pheochromocytoma coproducing catecholamines and VIP. While the two tumors might have developed synchronously, the finding of VIP secretion in the pheochromocytoma and the ganglioneuroma suggest that both tumors might originate from the same cell. Presentation: 6/1/2024