Paraneoplastic Effect for Thymoma...

[mountaindew2006]

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According to FA, Thymomas have Lambert Eaton syndrome as the paraneo effect. However, on the internet and on qbank, myasthenia gravis was the paraneo. WTF!!

The reason is, you know on the boards they'll probably describe mys Gravis or LE and you are going to know which neoplasm, or the reverse could be asked. And they'll have both as the answer choices i bet.

Anyone know the right answer? 😎

 

[Stinger86]

Although someone will probably clarify this with sickening detail, here's my take:

...Lambert Eaton syndrome is a myasthenia-like paraneoplastic syndrome of small cell carcinoma and other cancers. Myasthenia gravis is not a paraneoplastic syndrome, but a n autoimmune disease that is often associated with a thymoma in a certain percentage of afflicted patients.


In any case, on the boards if they describe LE syndrome and ask for the cancer, you put small cell carcinoma. If they describe myasthenia gravis and ask for other findings, you put thymoma. Just make sure you don't confuse LE and MG (in MG muscles get weaker with use, and in LE muscles get stronger with use)

 

[mountaindew2006]

yah i was thinking of that...i know the differences b/w LE and MG, but i suppose thats my only real option ...if they ask for a paraneo for either one just put Small cell by default. 👍

 

[Idiopathic]

Lambert-Eaton myasthenic syndrome has been associated with several cancers, including small cell, bladder, and thymoma.

About 15% of myasthenic patients (I looked that number up) are found to have thymomas. Lymphoma is apparently the most common mediastinal mass associated with myasthenia (as per our pathology professor).

 

[sunmoon]

According to the RRS by Dr.Goljan, 85% pts of MG have Thymic Hyperplasia with Germinal Follicles. Thymectomy is the tx of choice.

How to Diff b/w MG and LE:
MG : Symptoms get worse as day goes by with usage
LE : Symptoms get better as day goes by with usage

 

[Stinger86]

How to Diff b/w MG and LE:
MG : Symptoms get worse as day goes by with usage
LE : Symptoms get better as day goes by with usage

Also, it's good to know the physiologic explanation for this difference..

 

[sunmoon]

In MG, it is a defect of the Antibodies on the ACh receptor - preventing binding of ACh and so with usage, you deplete your reserves of ACh -> progressive weakening

In LE, it is a problem in the release of ACh from presynaptic terminals (most likely antiboidies against the presynaptic Calcium channels). So with usage, you increase the release of ACh leading to improvement of symptoms.

HTH.

 

[Idiopathic]

According to the RRS by Dr.Goljan, 85% pts of MG have Thymic Hyperplasia with Germinal Follicles. Thymectomy is the tx of choice.

And just so we are all clear, this is not thymoma.