V98 - Video Case Report: Sigmoid Colectomy for a Catecholamine Producing Neuroendocrine Tumor

Purpose/Background: Colon neuroendocrine tumors (NETs) are rare, accounting for 0.3% of all colon malignancies. Most colonic NETs are right-sided, usually found in the cecum. When left-sided, these lesions tend to be more aggressive. They are often discovered during screening endoscopy, with patients remaining asymptomatic until becoming obstructed. Common symptoms include abdominal pain, altered bowel habits, and bleeding. Infrequently, these tumors produce biochemically active peptides such as serotonin as seen in carcinoid syndrome. Other hormonal syndromes are much rarer. We present a case of a patient with medically refractory hypertension who underwent laparoscopic sigmoid colectomy for a catecholamine-producing NET.

Methods/Interventions: Our patient is a 34-year-old female, with an 11-year history of hypertension, severe headaches, and anxiety beginning after her first childbirth. Despite a three-drug regimen (doxazosin, amlodipine, atenolol), her blood pressure remained poorly controlled. Family history included pheochromocytoma and paraganglioma in a first-degree relative. A 24-hour urine catecholamine study revealed elevated normetanephrine (1876; normal 35-482). Dotatate PET scan showed a 2.8 x 2.2 cm sigmoid colon mass. Colonoscopy confirmed a submucosal lesion 20 cm from the anal verge. Genetic testing revealed a variant of undetermined significance for von Hippel-Lindau syndrome (p.S183L). After discussion, the patient was taken for a laparoscopic sigmoid colectomy. While the procedure was uncomplicated, intraoperative blood pressure spiked to a systolic of 220. Nicardipine was started postoperatively, and she was monitored in the ICU. Her antihypertensive regimen was resumed, and nicardipine was weaned by postoperative day 1. Blood pressure and symptoms rapidly improved, and she was discharged on day 3 on amlodipine alone. Pathology confirmed a well-differentiated (grade 1) NET with negative margins and 2/11 pericolic lymph nodes positive.

Results/Outcomes: Colonic NETs are rare (0.3 per 100,000), and are more commonly found in the small bowel, pancreas, appendix, and rectum. Distal colonic NETs behave more aggressively and may share molecular features with adenocarcinoma. Symptoms, when present, include pain, bleeding, obstruction, and bowel habit changes. Biochemical activity is rare, and usually carcinoid in presentation. Other hormonal syndromes, often associated with pancreatic NETs, are infrequently seen. Preoperative workup includes history, physical exam, imaging (CT/MRI, Dotatate PET), endoscopy, and biochemical evaluation if indicated. Surgical resection is the mainstay for stages 1-3. Somatostatin analogues are first-line for metastatic disease, with Everolimus as a second-line option. Chemotherapy is not supported by phase III data but may be considered for advanced cases. Follow-up is based on estimated risk of recurrence with serial imaging every 6-12 months for G1/2 lesions and every 3 months for G3. Endoscopy is recommended at 1 year for all patients.

Conclusion/Discussion: Colonic NETs are rare but increasing in incidence. While often found incidentally, they can be aggressive and present with biochemical activity. Our case highlights a rare colonic NET with normetanephrine production and symptoms resembling a pheochromocytoma. Given the recent rise in incidence and variable presentation, an improved understanding of tumor biology, diagnostics, and treatment guidelines is needed.