Traditional labs may not be very helpful. This includes the chemistry or the CBC. To diagnose an increase
in serotonin secretion, we collect a 24-hour urine 5-HIAA as well as a plasma chromogranin A level.
What’s chromogranin A? Neuroendocrine tumor vesicles secrete chromogranin A which is very specific
for neuroendocrine tumors. It is not dependent on serotonin secretion making it very, very ideal
for our diagnosis. It is more sensitive but less specific unfortunately than 5-HIAA. Recall 5-HIAA
is a metabolite of serotonin. Plasma levels correlate well with the treatment response. It’s important after treatment
of neuroendocrine tumors to follow the chromogranin A level. And it may have prognostic
value. Here’s an axial cross-sectional CT demonstrating potential locations of carcinoid tumor. You’ll notice
in the highlighted circles areas of the small intestines that may contain the tumor.
Sometimes, octreotide scans are also helpful to delineate where exactly the carcinoid tumor may be. At surgery,
if it was in a small bowel carcinoid with no metastasis, this is what we would do, a segmental
small bowel resection. You’ll notice from this image that a segment of small intestines has been removed
or placed out of continuity. The remainder of the small bowel will be put back together either in a
hands-on or a stapled manner. Here’s what a carcinoid tumor might look like in the actual
small intestine specimen. Very important discussion about liver degradation: Remember my discussion
about how metastasis is very important in the development of neuroendocrine tumor or carcinoid
tumor symptoms? The reason is this. Vasoactive peptides are usually degraded by the liver.
However, when these vasoactive peptides overwhelm the liver degradation, this implies that the
primary tumor has spread beyond the liver or beyond the liver’s ability to degrade the vasoactive peptides.
Only when the carcinoid tumor spreads beyond the liver do patients become symptomatic. Important clinical
pearls: Carcinoid tumors are largely well differentiated and indolent tumors. Most carcinoid tumors
do not lead to the carcinoid syndrome. Our liver have extreme protective mechanisms and they will degrade
the vasoactive peptides. High-yield for examination: Symptoms of carcinoid syndrome,
just as a reminder, flushing, cardiac complications, tricuspid regurgitation, abdominal pain, all imply
a spread to the liver. Bronchial tumors can cause carcinoid syndrome because of direct secretion
to the systemic circulation. Again, if the tumor was in the bronchial system or the lungs, the liver
has not had the chance to degrade the vasoactive peptides. The serotonin can then directly go
into the systemic circulation. For patients who have bronchial tumors, their symptoms may occur
earlier than those who had GI carcinoid tumors. Thank you very much for joining me on this discussion
of carcinoid syndrome.