Mesenteric Lymph node and Carcinoid Q

[teehees]

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Kaplan states mesenteric lymph nodes do NOT cause carcinoid syndrome because it drains into the portal circulation.

I thought it drained directly into the systemic venous circulation?

In which case mesenteric lymph node mets is a better option than hepatic mets for causing carcinoid syndrome.

Thoughts?

 

[1badvette]

In order for the symptoms mentioned to be present a LIVER metastases must take place .. a localized Carcinoid tumor and a normal functioning liver will not present with symptoms mentioned above.

 

[teehees]

I think you misunderstood what I'm trying to ask

For symptoms of carcinoid to occur, the tumor must have metastasised as otherwise the liver metabolises serotonin causing no symptoms.

I'm asking that isn't a mesenteric lymph node metastasis more likely to yield symptoms than a hepatic metastasis?

Kaplan explanation says no because mesenteric lymph nodes drain to portal circulation. BUT according to wikipedia and what i remember studying for step 1 they go to cysterna chyli -> thoracic duct -> jugular vein (skipping the liver)?

 

[1badvette]

I think you're digging to deep into it which will end up hurting you on this exam .. Step 1 was a while back for me , and Wikipedia should be taken off your resources list at this stage of your study . I Checked on uptodate and according to them the liver is they most common site for mets . The lymph node mets might not cause a large enough spike in serotonin to cause symptoms , or maybe kaplan is right and they do drain into the portal system .

 

[Nabin]

I thought it drained directly into the systemic venous circulation?

Yes. The mesenteric lymph nodes do drain into the systemic venous circulation via the thoracic duct. They don't drain into the portal venous system. That's what I have always read too.

I'm asking that isn't a mesenteric lymph node metastasis more likely to yield symptoms than a hepatic metastasis?

The question is "what most likely coexists?". So, epidemiologically, liver metastasis is the most common cause of carcinoid syndrome. And that will be your answer for this question with a carcinoid tumor in the small intestine. Theoretically, you may not be wrong in thinking that if it metastasized into the mesenteric nodes, there would be a more likely chance for the syndrome to happen since it would then bypass the liver. But, that doesn't seem to happen. Maybe the predilection for the neuroendocrine cells to secrete hormones into the bloodstream to send them to the liver via the portal system is much more than the likelihood of the hormones being passed on to the mesenteric lymph nodes.

 

[teehees]

Thanks guys. Yes I agree I was overthinking it and its probably not the most likely thing to occur epidemiologically, my first reflex was hepatic metastasis but then convinced myself out of it

 

[Nabin]

Like 1badvette said, don't overthink than what's necessary. Its so much more important to not do that in step 2 CK. Many people make a bunch of mistakes over thinking stuffs that could have been solved by a couple of simple logic. While its important to dig deep and learn as much as you can, remember its an exam where you need to score high. Think simple. Make simple connections. Apply that in the exam day. You will do good.