Carcinoid tumors commonly originate in the gastrointestinal tract and can present with vague abdominal symptoms and nonspecific radiologic findings. Clinical diagnosis is difficult, and standard radiographic studies often miss the primary tumor?thus, diagnosis is often made after metastasis. Metastatic lesions are associated with a lower 5-year survival rate, thereby increasing the impetus for early diagnosis and intervention. This report highlights the clinical challenges with carcinoid diagnosis and identifies the need for general practitioners, specialists, interventionalists, and surgeons alike to consider alternative diagnosis when confronted with intractable gastrointestinal complaints.

Occurring predominantly in the gastrointestinal tract and lung, carcinoid tumors arise from neuroendocrine cells and are traditionally classified according to their embryologic site of origin?the foregut, midgut, or hindgut. Foregut carcinoid tumors originate most commonly in the lungs, bronchi, or stomach; midgut tumors in the small intestine, appendix, or proximal large bowel; and hindgut tumors in the distal colon and rectum. Each subgroup has its own set of biologic and clinical characteristics.¹

A 57-year-old Caucasian female presented with cramping right lower quadrant abdominal pain after meals and a 9-year history of Crohn’s disease that was refractory to medical management. She denied hematochezia, nausea, and vomiting, but noted steady weight loss over a number of years. Her treatment at various points in her course included adalimumab, azathioprine, and prednisone. She had a number of previous operations including Nissen fundoplication with revision, appendectomy, cholecystectomy, hysterectomy, and coronary bypass.

During the examination, she appeared healthy with stable vital signs. Her abdomen was soft, without distention, but she had diffuse tenderness without focal peritoneal signs. Laboratory findings included an albumin of 2.3 g/dL, C-reactive protein of 0.06 mg/L, and erythrocyte sedimentation rate of 105 mm/h. Computed tomography (CT) showed thickening of the cecum and terminal ileum with mesenteric inflammation consistent with Crohn’s disease (Fig. 1). Small bowel follow-through showed no evidence of stricture. At exploration, the distal ileum appeared ischemic, but a strong pulse was felt in the superior mesenteric artery and ileocolic artery. Around the terminal ileocolic artery, there was a fibrotic, contracted area of mesentery (Fig. 2). The involved segment was resected as part of an ileocecectomy and primary anastomosis.

Pathological examination demonstrated a carcinoid tumor of the small bowel, specifically a neuroendocrine tumor in the mesentery of the terminal ileum with local fibrotic changes and bowel ischemia. The tumor was determined to be a metastasis from an unidentified primary site, and systemic therapy was initiated.^2,3

Carcinoid tumors of the small bowel make up approximately one-third of small-bowel tumors and are thought to arise from serotonin-producing intraepithelial endocrine cells. They are most frequently found in the distal ileum, are often multicentric, and typically have a gross appearance of small, firm submucosal nodules.² They are commonly associated with both mesenteric nodal disease and a local desmoplastic reaction to humoral agents elaborated by the tumor that can cause intermittent abdominal pain or small-bowel obstruction. Routine radiological imaging, such as CT and contrast studies, rarely identifies the primary tumor, so patients may have vague abdominal symptoms for years prior to the diagnosis. As a result, the majority of patients with small-bowel carcinoid present with metastases to the lymph nodes or liver.²

The treatment of small bowel carcinoid tumors is based on tumor size, location, and the presence or absence of metastasis. For small tumors (<1 cm) and no evidence of metastasis, a segmental resection is recommended. For larger tumors, multiple tumors, or regional lymph node metastasis, wide excision of the bowel and mesentery is required.¹ For widespread metastasis, surgery is still indicated as debulking can provide symptomatic relief.¹ Other management options for clinically significant progressive disease include hepatic regional therapy (arterial embolization, chemo-embolization, or radioembolization) or cytoreductive surgery (ablative therapy).⁴ The goal of medical therapy is to relieve symptoms from the excessive production of humoral factors. Octreotide, a somatostatin analog, may decrease the secretory activity of the carcinoid and may also have an antiproliferative effect.

The overall 5-year survival rate for carcinoid tumors (excluding appendiceal) is approximately 90% but approaches 100% for non-metastatic disease resected from the primary site. The 5-year survival rates for patients with regional disease and those with distant metastasis are 65% and 25?35%, respectively.¹ Early diagnosis and surgery are thus imperative. The lack of specific radiological findings make early diagnosis a challenge, so a high level of clinical suspicion in the face of refractory symptoms is required to find localized disease before metastases occur.

In our patient, pathology did not reveal a primary tumor in the resected ileum or right colon. Serum chromogranin A was within normal values, and an octreotide scan did not indicate pathologic activity. It is our hypothesis that the primary tumor was resected during her previous appendectomy > 25 years earlier. Her clinical presentation likely resulted from metastatic disease and had been incorrectly interpreted as Crohn’s throughout her longstanding preoperative course. Even with advanced imaging techniques, metastatic carcinoid is difficult to diagnosis. Our patient’s story is a clinical reminder to consider alternative pathologies in the face of refractory disease.