Case by Case with Dr Chris Allan

The problem

Carcinoid tumours are rare and they arise primarily within the mucosa and submucosa of the gastrointestinal tract and the bronchial tree. They arise from neuroendocrine cells which secrete hormonally active substances that can have both local and distant effects throughout the body. Carcinoid tumours secrete these substances, the most common being serotonin.

Carcinoid syndrome

The serotonin secreted by carcinoid tumours causes surrounding blood vessels to constrict which deprives the tissues of blood supply and ultimately leads to stricturing and fibrosis. Because all blood which drains from the gastrointestinal tract passes through the liver, the serotonin produced by a carcinoid is degraded and subsequently excreted in the urine.

Carcinoids are very slow growing, but malignant, and can metastasise to surrounding lymph nodes and the liver. This is usually only seen once they become larger than 1–2 cm in diameter. When carcinoids metastasise to the liver, the serotonin they secrete can escape into general circulation and produce a constellation of symptoms (flushing, wheezing and diarrhoea) known as the carcinoid syndrome. After some years the serotonin can begin to affect the right sided heart valves, causing them to become fibrotic.

Here are four cases that presented recently.

Case 1: Coincidental appendix carcinoid

The patient was a 17-year-old female with appendicitis requiring laparoscopic appendicectomy. Aside from appendicitis, our pathologists identified a coincidental 1 cm carcinoid tumour in the tip of the appendix.

Case 2: Small bowel carcinoids

This case involved a 78-year-old woman who presented with a five-day history of a small bowel obstruction. She required a laparotomy and the obstruction was clearly caused by a band adhesion over the distal small bowel which probably arose following a hysterectomy many years earlier. At operation there were two small nodules within the small bowel near to the point of obstruction. This loop of bowel was removed and both lesions were carcinoid tumours.

Case 3: Carcinoid within a Meckel’s diverticulum

A 37-year-old woman presented with a short history suggesting small bowel obstruction which was confirmed on a CT scan. She proceeded to laparoscopy which revealed a Meckel’s (congenital) diverticulum associated with an obstructed loop of small bowel (Figure 1). The obstruction was reduced and the diverticulum resected via mini-laparotomy (Figure 2). Our pathologists found a coincidental 1.2 mm carcinoid within the diverticulum.

Case 4: Colonic carcinoid

A 77-year-old lady presented with a recurrent obstruction of the distal colon. A CT scan (Figure 3) revealed this was most likely due to a stricture caused by diverticular disease. She required a laparotomy and resection of the sigmoid colon and colostomy formation. Our pathologists found the obstruction was due to stricturing from a carcinoid tumour in the sigmoid colon. The patient had a small bowel carcinoid resected three years earlier.

Operation

Because of their small size, primary carcinoids are usually not appreciated on imaging such as CT scans and are typically only found at operation, either due to the effects they have had on the bowel, such as stricturing and obstruction, or they are a coincidental finding. Carcinoids can be multiple and typically require resection of the length of bowel they arise in and the adjacent mesentery to remove the local lymph nodes.

Post-Op

There is no effective chemotherapy for carcinoids and so after removal they require long term followup. This involves enquiring about the symptoms of the carcinoid syndrome, blood tests for platelet serotonin levels and ultrasound or CT scanning. There is a specialised nuclear medicine scan which uses a substance called octreotide, labelled with a low dose radioactive tracer. The octreotide binds to the serotonin receptor on carcinoid cells and the tracer enables their identification on the scan. Octreotide is also used to treat the symptoms of the carcinoid syndrome by decreasing the production of serotonin. Occasionally, carcinoid metastases in the liver can be removed. Those who develop carcinoid heart disease may require valvular surgery.

If you would like to submit a Case by Case article, please email the case details to the Editor, miranda.hunt@mater.org.au. All cases submitted should include a brief background, description of how the case progressed and the outcome.