NEUROENDOCRINE TUMOR MIMICKING CROHN'S DISEASE: A CASE REPORT

Case Presentation A 43-year-old male patient presented with recurrent episodes of colicky abdominal pain and intermittent abdominal distension over the past four years, initially diagnosed as Crohn's disease. He was on prednisone 40 mg/day and azathioprine 100 mg/day, scheduled to begin biological therapy with infliximab. Laboratory tests showed a C-reactive protein level of 2.98 mg/dL and fecal calprotectin of 553 µg/g. Colonoscopy revealed a thickened mucosa in the terminal ileum, with vascular pattern obliteration but no erosions or ulcers. Entero-CT showed focal, asymmetric wall thickening in an ileal loop segment in the right iliac fossa, measuring 5.0 cm, causing angulation of the intestinal segment and significant luminal narrowing. This led to upstream ileal distension with fecaloid material, suggesting partial intestinal obstruction. Prominent mesenteric lymph nodes were noted, the largest measuring 2.0 × 1.0 cm. A review of CT images raised suspicion of a primary small bowel neoplasm. The patient underwent segmental enterectomy with primary anastomosis without complications. He experienced significant clinical improvement, with cessation of prior episodes of partial intestinal obstruction. Histopathological analysis revealed a well-differentiated, low-grade neuroendocrine tumor (NET) of the small intestine, pT2N1, located in the ileum, measuring 2.5 × 1.5 cm, invading the muscularis propria, with clear margins and angiolymphatic invasion. Immunohistochemistry showed Ki-67 positivity in 1%.

Discussion Neuroendocrine tumors (NETs) are rare neoplasms with nonspecific presentations and slow growth, often excluded from the initial differential diagnosis. Most NETs of the jejunum and ileum are non-functioning tumors but may exhibit hepatic metastases and carcinoid syndrome. At diagnosis, these tumors are typically >2 cm, involving the muscularis propria with regional lymph node metastases. Clinical manifestations include abdominal pain, intestinal obstruction, diarrhea, weight loss, and bleeding. Surgical intervention remains the treatment of choice whenever feasible.

Conclusion This case highlights the importance of considering differential diagnoses in patients with suspected Crohn's disease. In this instance, careful reassessment of the clinical history and complementary examinations was critical in revising the initial diagnosis.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
25 April 2025