Diagnosis: Carcinoid tumor
Based on the patient’s symptoms and imaging studies, we suspected that she had a carcinoid tumor with mesenteric involvement. The CT showed a 2.6-cm mesenteric mass with a characteristic sunburst pattern and desmoplastic stranding, as well as numerous prominent retroperitoneal lymph nodes, suggestive of nodal involvement. The octreotide scan showed abnormal focal intense radiotracer uptake in the corresponding right lower quadrant mass, which confirmed our suspicion. There was no evidence of hepatic metastasis on the CT or octreotide scan.
Most common locations
Carcinoid tumors are the most common type of neuroendocrine tumors and are derived primarily from serotonin-producing enterochromaffin cells.1 These slow-growing, well-differentiated tumors usually originate in the gastrointestinal and bronchopulmonary tracts (67.5% and 25.3%, respectively), with uncommon primary sites involving the mesentery, ovaries, and kidneys.2 Generally, carcinoid tumors that arise in the mesentery are metastatic, often from an occult primary site. It has been reported that 40% to 80% of midgut carcinoid tumors spread to the mesentery.3
Carcinoid tumors are estimated to occur in 1.9 individuals per 100,000 annually.4 Traditionally, the appendix was cited as the most common location for these tumors. However, more recently, Modlin et al2 conducted a comprehensive analysis of epidemiologic data from the 13,715 carcinoid tumors registered in the National Cancer Institute database. Over the more than 25-year study period (1973-1999), Modlin and colleagues found a significant change in the distribution of gastrointestinal carcinoid tumors, with the incidence rates of small bowel (41.8%) and rectal carcinoids (27.4%) increasing, while appendiceal carcinoids decreased (24.1%).2
Gastrointestinal complications can arise from metastasis
Small bowel carcinoid tumors often manifest with intermittent abdominal pain, which can be caused by fibrosis of the mesentery, intestinal obstruction, or kinking of the bowel. Less common is the constellation of diarrhea, cutaneous flushing, and asthma seen with carcinoid syndrome. The prevalence of this syndrome is mediated by various humoral factors, the most notable of which is serotonin.
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