Midgut Carcinoid is the type of Carcinoid tumor. General introduction Carcinoids are rare slowly growing, neuroendocrine tumors. In 1907 Obendorfer was the first to use the term carcinoid (Karzinoide). He described an ileal tumor with a much slower progression than expected from denocarcinomas.
The traditional classification of the carcinoids according to their embryonal site of origin was introduced in 1963. It comprises foregut-(in the lung, thymus, stomach, pancreas and proximal duodenum) midgut- (from the distal duodenum to proximal colon) and hindgut carcinoids (origin in the distal colon enrectum). This classification corresponds consequently to their vascular supply, namely the celiac axis, superior mesenteric artery and inferior mesenteric artery.
Carcinoids can develop in almost all organs arising from the primitive entoder as well as the ovary and retroperitoneum.
In this thesis we will especially focus on the midgut carcinoids. The midgut carcinoids are usually referred to as the “classical” carcinoids. They arise from cells of Kulchitsky in the intestinal crypts and display, when producing serotonin, both an argentaffin and argyrophilic staining reaction. Midgut carcinoids can produce several biogenic amines such as serotonin, radykinin, prostaglandin, catecholamines and substance P. These products only exert their influence once they have passed the liver into the systemic circulation, as the liver is able to metabolize these amines. An ovarian carcinoid can therefore cause early symptoms because the ovary drains directly into the caval vein and not into the portal vein. In case of liver metastases, the liver itself becomes a production site of these amines which then enter the systemic circulation causing several symptoms we refer to as the carcinoid syndrome, i.e.
hot flushes, diarrhea and circulatory imbalance. The carcinoid patient with the classical symptoms will often be diagnosed as having widespread hepatic metastases. This delay is partly explained by the relatively small mass effect of the primary tumor that causes only mild symptoms. At laparotomy a small
primary tumor and massive metastatic disease is suggestive for carcinoid disease.
From the surgeon’s point of view there are two major groups of carcinoid patients, those who are accidentally diagnosed during appendectomy for a suspected appendicitis and those who are referred by the gastroenterologist or medical oncologist, and are often metastasized. The first group offers no problems and abdominal spread or liver metastases are rare in these cases.5-7 In case of metastasized patients however the medical oncologist, surgical oncologist and the patient have to weigh several treatment options and the timing of interventions. Although the treatment is usually palliative in case of etastases, patients can survive many years.
Aim of this thesis
The aim of this thesis is to get insight in surgical aspects of the treatment of carcinoid patients and the role of vasoactive substances produced by the tumor and their vascular effects.

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