IS Case 351: Primary carcinoid tumor of the small bowel
2009 URMC Imaging Sciences
Publication Date: 2009-11-09
CT demonstrates 2 submucosal lesions within the ileum compatible with primary small bowel carcinoid tumor. A spiculated mass of metastatic mesenteric lymph nodes is seen adjacent to the bowel lesions with spiculation / retraction compatible with metastasis. There are liver metastases which show arterial-phase enhancement.
Carcinoid is the commonest small bowel primary tumor and is typically a low-grade malignancy. It primarily occurs in the 5th to 6th decades and has a 2-to-1 male-to-female predominance. It originates from submucosal neuroendocrine cells. The tumor is usually small, not able to be seen on CT and can be associated with high serotonin levels.
One-quarter to one-third of carcinoid tumors occur in the small bowel. Of these, the majority occur in the ileum. Three-quarters of symptomatic patients have midgut carcinoid tumors. Nearly one-third of patients with small bowel carcinoid have a second primary within the gastrointestinal tract.
There may be local and lymphatic spread of tumor. Regional adenopathy occurs often. Hematogenous metastases to the liver result in carcinoid syndrome with skin flushing, headache and gastrointestinal disturbance.
CT demonstrates a vascular, submucosal lesion typically within the ileum when arising in the small bowel. A spiculated mass of metastatic mesenteric lymph nodes is seen adjacent to the bowel lesion and can exhibit calcification. There can be local stellate desmoplastic reaction with mesenteric retraction, small bowel kinking/displacement/separation and small bowel wall thickening. Lymphadenopathy can be low attenuation secondary to necrosis. Liver metastases typically show arterial-phase enhancement and become isoattenuating in the portal venous phase of CT.
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