PSAT007 Pheochromocytoma Presenting With Small Bowel Obstruction

BACKGROUND: Pheochromocytoma is a rare catecholamine producing tumor arising from the adrenal gland with estimated prevalence of 0.1%-0.6%. Most common signs and symptoms of pheochromocytoma, i.e. headache, palpitations and sweating are non-specific and often mimic other diseases. The association between pheochromocytoma and small bowel obstruction however is rarely recognized. CASE: 55-year-old Russian male with past medical history of alcohol abuse, smoking and hypertension presented to ER with chest pain, abdominal pain, nausea, vomiting, poor appetite, diarrhea and 20 lbs weight loss for 2-3 months. On presentation, patient was hypertensive with blood pressure of 225/137 mm/Hg and heart rate of 126 beats/minute. He appeared uncomfortable, skin was flushed, and he was noted to be tachycardic with distended abdomen and sluggish bowel sounds. Initial laboratory studies revealed hyperkalemia of 7.8 mmol/L, CO(2) 13 mmol/L, anion gap 21 mEq/L, acute kidney injury with creatinine 1.34 mg/dL, venous pH 7.18, lactic acid of 5.7 mmol/L. A polymerase chain reaction test for COVID-19 was negative. Alcohol and urine drug screen were negative. Persistent diarrhea, abdominal pain with distention prompted evaluation with abdominal X-ray which showed distended small bowel loops. As part of the hypertensive crisis work up, CT angiogram of the chest, abdomen and pelvis with contrast was done and it demonstrated an enhancing left adrenal mass 4.6×4.5 cm with 35 Hounsfield units on the non-contrast study and 95 Hounsfield units on the venous phase. Evaluation of plasma hormone levels revealed elevated metanephrines >5,000 pg/mL (n 0-88 pg/mL) and normetanephrine >6,000 pg/mL (n 0-137 pg/mL). The 24-h urinary catecholamines were highly elevated with metanephrine >9,000 ug (n 58-276 ug/24hr) and normetanephrine >12,000 ug (n 156-729 ug/24hr). Patient was initially treated with Labetalol infusion with noted improvement in diarrhea. His hospital course was complicated by an acute myocardial infarction with cardiac thrombus. Patient was stabilized with Prazosin and discharged from the hospital. One month later he underwent left laparoscopic adrenalectomy. Gross pathology showed 5.1×4.5×3.8 cm adrenal mass with immunohistochemical staining supporting a diagnosis of pheochromocytoma. DISCUSSION: Recognition of clinical features of pheochromocytoma is often challenging but important due to its high morbidity and mortality rates. Small bowel obstruction in association with pheochromocytoma is uncommon. In smaller case series, ileus, megacolon, and bowel infarction was observed in patients with larger adrenal masses, typically >70 grams and catecholamine levels more than 4 times the upper limit of normal. This case highlights the importance of maintaining high index of clinical suspicion in early recognition of the gastrointestinal manifestations of pheochromocytoma and its potentially catastrophic consequences. REFERENCES: (1) Hodin R, Diagnosis, and management of pheochromocytoma. Curr Probl Surg. April 2014 Apr;151-87. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.