Of the gastrointestinal carcinoids, those arising from the midgut (e.g. small intestine and appendix) are by far the most common, with tumors distal to the jejunum representing 96% of carcinoids located in the gastrointestinal tract . These midgut carcinoids secrete serotonin and are responsible for the carcinoid syndrome, the intractable flushing and diarrhea associated with metastasis to the liver. In addition to hepatic metastasis, midgut carcinoids also commonly metastasize to the small bowel mesentery . Indeed, radiographic studies indicate mesenteric involvement in 40-80% of patients with abdominal carcinoid tumors [9–11].
Carcinoid metastases to the mesentery often grow far larger than the submucosal primary tumors in the small bowel wall, and they are responsible for much of the morbidity and mortality of gastrointestinal carcinoid tumor that is not attributable to carcinoid syndrome itself. Many patients with mesenteric carcinoid present with small bowel obstructive symptoms due to tethering and kinking of the small bowel to the rigid mesentery. In several surgical case series of patients with midgut carcinoids, 62-67% required laparotomy for either intestinal obstruction or abdominal pain, and of these patients, 67-79% had evidence of extensive mesenteric fibrosis upon surgical exploration [12, 13]. In other cases, the mesenteric vasculature (e.g. superior mesenteric artery and vein) can become completely encased in tumor, causing regional portal hypertension and arterial insufficiency [14–16]. The encasement of the visceral vasculature may manifest as episodes of post-prandial acute abdominal pain or as GI bleeds (noted in 5% of midgut carcinoid patients in one case series) [3, 13].
Although somatostatin analogs such as octreotide remain the mainstay of carcinoid therapy, surgical resection has emerged as a vital treatment in disease management. For metastatic disease, palliative cytoreductive surgery has been employed by some groups to specifically address mesenteric carcinoids. While some symptomatic improvement is often reported, long-term outcomes are compromised by recurrent disease [5, 17, 18]. Unfortunately, large mesenteric carcinoids have often been considered unresectable due to their position abutting critical vascular structures in the abdomen.
Recently, however, several groups have published reports outlining the use of intestinal autotransplantation to safely gain access and resect tumors that encase the vasculature of the mesenteric root. Utilizing techniques from intestinal allotransplantation, the patient's small intestine is harvested en bloc and maintained in cold preservative fluid to limit warm ischemia injury. The mesenteric mass is then fully excised, and the intestine is autotransplanted back into the patient. This strategy was first employed by David Lai and colleagues to treat a nonfunctioning islet cell carcinoma . That patient also underwent a total pancreatectomy, gastrectomy, splenectomy and hepatic revascularization (as his proximal hepatic artery was also resected). Vascular anastomoses were performed between the hepatic artery and aorta, distal superior mesenteric artery and aorta, and between the distal superior mesenteric vein and cephalad portal vein.
A similar approach was employed by Tzakis and colleagues to treat four patients with lesions involving the root of the mesentery. The indications for resection in these patients were pancreatic head fibroma, vascular malformation at the mesenteric root, desmoid tumor of the pancreatic tail, and locally advanced pancreatic adenocarcinoma [20, 21]. Whereas we employed in situ resection of the carcinoid tumor, the patients in Tzakis' case series had ex vivo resection of their lesions on ice on the back table after their organs had been removed en bloc. The mesenteric lesions of his series did not apparently extend into the distal branches of the SMA, obviating the need to autotransplant multiple segments of intestine as in the case we present here. All of his patients had good outcomes except for the patient treated for pancreatic cancer, who died of hepatic metastases 7 months postoperatively. Two additional case reports of intestinal autotransplantation to treat locally-advanced pancreatic cancer extending into the mesenteric root were also complicated by rapid recurrence of hepatic or peritoneal metastases, and early death after the procedure [22, 23]. These reports cast doubt on whether this aggressive surgical strategy is warranted for cases of pancreatic cancer.