Moving on, carcinoid syndrome.
And this is due largely to the elaboration
by the carcinoid tumor of serotonin,
which causes effects at a distance.
Carcinoid tumor are most common in the GI
tract but you can have ovarian carcinoid,
you can have primary pulmonary
carcinoids, you can have others,
but the most common ones are going to be in
the GI tract, particularly in the small bowel.
And what we're showing here with the
green arrow on the left hand side
is a segment of proximal jejunum and in
it is a kind of a single nodular mass
that we've incised multiple times.
It wasn't cut in nature, that's the pathologist.
And then when we look at it histologically,
it is a monomorphous population
of small round blue cells with granular cytoplasm.
These guys are making a variety
of small molecular weight hormones
and include the production of serotonin.
Now, in general, even if that tumor
which is usually a fairly indolent tumor
is considered a malignant tumor,
but it's indolent, grows slowly,
if even if that tumor is making its serotonin
and other molecules that it's going to release,
the liver metabolizes that, so we have no effect.
However, once the tumor metabolizes to the liver,
and we replace a significant chunk of the liver
with the tumor, as we see here on this slide,
on the left hand side is the
mass, metastatic carcinoid,
on the right, are the nests of the
carcinoid cells within the liver.
At that point, now the liver can't metabolize
all the serotonin that's being released.
And now we're going to get systemic effects
due to the serotonin washing over endothelium,
upstream, or downstream.
So from that liver metastasis, not being
able to completely metabolize old serotonin,
we're releasing it into the
vasculature into the hepatic vein
into the inferior vena cava into the heart.
And the first kind of the tissue
that's going to be affected by this
are going to be the valvular tissues.
So in carcinoid syndrome, there
can be other manifestations
but here for example, we're going to be
talking about what happens to the valves.
In this patient, there was a significant
tumor burden within the liver,
significant serotonin levels washing over the valves.
The tricuspid valve on the right is
thickened because of an intimal hyperplasia
due to smooth muscle proliferation
and matrix synthesis.
And that valve has become somewhat
incompetent as a result of that.
So the valve has been thickened
and we get tricuspid insufficiency.
The mitral valve, however, is completely unaffected.
That's a completely normal
valve on the left hand side.
That's because now as these 'evil humors'
as we refer to them, the serotonin
goes through the lung, the lung
endothelium is able to metabolize it.
So the the left sided valves in a patient
with metastatic carcinoid involving the liver
are not involved.
It's the right side of valves that are seeing
this first and we will get this thickening
due to smooth muscle
proliferation of intimal hyperplasia.
Well, that also means that, Gee the pulmonic
valve must also be involved and yes it is.
So you can see that the aortic valve valve in this
patient completely normal on the left hand side.
The pulmonic valve in comparison
is markedly thickened and stiff,
so that we will have a degree of pulmonic stenosis.
So classic carcinoid syndrome involving
the heart, carcinoid heart disease
due to serotonin release is going
to cause tricuspid insufficiency
and pulmonic stenosis in severe cases.