EP957 - Unexpected Discovery: Neuroendocrine Tumor in Meckel’s Diverticulum During Surgery for Sigmoid Volvulus

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Purpose/Background: Meckel's diverticulum is the most common congenital anomaly of the gastrointestinal tract, occurring in approximately 2% of people. While typically asymptomatic, it can present with complications such as diverticulitis, gastrointestinal bleeding, or malignancy. The most common malignancies arising from Meckel's diverticulum are neuroendocrine tumors (NETs), found in approximately 0.5% to 3.2% of symptomatic cases . Despite their infrequency, NETs carry a significant risk of metastasis, particularly to the lymph nodes and liver. This report presents a 74-year-old male with sigmoid volvulus and an incidental finding of a neuroendocrine tumor in Meckel’s diverticulum.

Methods/Interventions: Case report of neuroendocrine tumor within a Meckel's diverticulum.

Results/Outcomes: A 74-year-old male with a history of schizophrenia, colon cancer status post-chemotherapy and partial sigmoid resection, and ileus presented to the ED with black stools and generalized weakness. Physical examination revealed diffuse abdominal tenderness, and the patient reported dark, clay-like stools. A CT scan revealed diffuse gaseous distension of the sigmoid colon consistent with volvulus, alongside colitis. Laboratory findings included leukocytosis at 17.1 × 10⁹ cells/L. Ceftriaxone was initiated. Surgery was consulted, and sigmoid volvulus was confirmed through colonoscopy. Decompression with a rectal tube was performed.
The patient’s course was complicated by C. difficile infection, requiring a 10-day course of vancomycin, which delayed surgical intervention. After resolution of the infection, the patient underwent laparoscopic sigmoidectomy with end colostomy on day 23. During surgery, a diverticulum on the antimesenteric border of the distal ileum, presumed to be Meckel’s diverticulum, was discovered with a 1 cm mass protruding from its tip. A stapled diverticulectomy was performed. Postoperatively, the patient recovered well and was discharged after completing an antibiotic course.
Histopathology revealed ectopic gastric mucosa and a well-differentiated neuroendocrine tumor measuring 0.5 cm, involving the muscularis propria. The tumor cells were positive for chromogranin, synaptophysin, and AE1/AE3, with a Ki-67 index below 3%, indicating low proliferative activity. No lymphovascular invasion was noted, and resection margins were clear. The patient was referred to oncology and reported appropriate bowel function during follow-up.

Conclusion/Discussion: Meckel’s diverticulum can cause complications like gastrointestinal bleeding or malignancies, such as neuroendocrine tumors (NETs), which carry a high risk of metastasis to lymph nodes and the liver. Tumors smaller than 1 cm have a 26.5% risk of metastasis, increasing to 53.6% for 1-2 cm and 73.7% for tumors larger than 2 cm. In this case, the patient’s 0.5 cm neuroendocrine tumor showed low proliferative activity (Ki-67 < 3%), suggesting a lower risk of metastasis, though complete resection was necessary as small tumors can still metastasize.
Management of incidental Meckel's diverticulum is debated. Some recommend resection during surgery, especially if malignancy or ectopic tissue is present. In this case, diverticulectomy was performed after incidental discovery during surgery, and pathology revealed the neuroendocrine tumor postoperatively. Wider resection was avoided, aligning with recommendations to avoid extensive surgery without aggressive tumor features. Proper oncologic follow-up was stressed.