Case Presentation: We present a case of a 59 year old man with a history of HTN, T2DM (a1c 8.3%) and splenectomy in 1981 who presented with two weeks of progressive constipation, episodic flushing, sweating, palpitations and severe lightheadedness, no longer able to stand.On admission he was tachycardic to 140 and hypertensive to 200/120. CT abdomen/pelvis noted a 5.1cm right adrenal mass. A primary adrenal tumor vs. metastatic disease were considered and 24-hour urine studies confirmed a pheochromocytoma: VMA 38mg/gCr; metanephrine 3,120ug/gCr; normetanephrine 7,663ug/gCr. Resection was planned pending optimization of alpha & beta blockade, achieved with phenoxybenzamine and metoprolol.After admission he developed a progressively worsening ileus despite an aggressive bowel regimen. An NG tube was placed for decompression and his Ileus resolved in 5 days.One week later he developed painless abdominal distension. His HR and BP remained stable. A scheduled PET/CT that day was negative for metastatic disease but identified pneumoperitoneum. He was emergently taken to the OR for exploratory laparotomy where a perforated distal ileum was resected with the pheochromocytoma.Pathology of the resected ileal tissue identified Mucormycosis and CMV. He subsequently developed an anastomotic leak. Further surgery was deferred by patient and surgical team through shared decision making. Despite medical management he progressively declined and transitioned to inpatient hospice.

Discussion: Pheochromocytomas are rare but potentially deadly tumors [1] and may be considered in patients with resistant HTN, periodic hyperadrenergic spells,[2] or an adrenal mass. Adrenal incidentalomas >1cm should be evaluated for malignancy and/or hormonal hyperfunctioning. Prioritization for additional studies performed based on imaging characteristics and clinical suspicion.[3] Additional tests to identify pheochromocytomas include urinary fractionated or plasma free metanephrines.[1]Constipation, GI bleeds and bowel perforation are established but underrecognized complications of pheochromocytomas[4,5,6] and warrant additional attention. Smooth muscle of the GI tract contains α1, α2 and β2 receptors.[4,6] Catecholamine excess can directly inhibit intestinal motility and also cause vasoconstriction leading to bowel wall ischemia, further decreasing motility while predisposing patients to GI bleeds and perforations.[4,6] Alpha and beta blockade is often inadequate in controlling catecholamine toxicity in the GI tract.[4]

Conclusions: Bowel perforation in the setting of an intestinal pseudo-obstruction or ileus is a rare but serious complication of pheochromocytomas, likely due to a combination of altered motility and intestinal ischemia from vasoconstriction.[5,6] Catecholamine blockade is often inadequate to control gastrointestinal toxic effects of catecholamine surges and patients should be on adequate bowel regimens to prevent constipation.[4] Clinicians should closely monitor patients for this life threatening complication and subtle changes in clinical status or exam should prompt careful reevaluation.Of note, there is no clear explanation for his Mucormycosis infection as there was no known immunodeficiency (negative HIV and no remarkable infectious history). It is hypothesized that Mucormycosis was introduced during his NG tube placement and his asplenism, underlying diabetes and poor intestinal perfusion from his pheochromocytoma increased his risk of disseminated infection.