Thanks for this. Our daughter, also in LTM, has the same rash around her mouth and nose, but it goes away during steroid week. We were advised to use Aquaphor and that works pretty well.

See- I just knew that there was a reasonable explanation.  Here in the Hoosier state, the onc said it was psoriasis and the PCP said chemo.  Ha!  They both loose.  Good news for us was that it only lasted a few cycles and then just quit showing up.  Hopefully that will happen w/ Eli (though it doesn't sound like it has).

We were told by our hospital that the rash was definately a result of the 6MP , but that some kids have it from the methotrexate as well.  It may even be a combination of the two.  Since steroids are anti inflammatory, once they are discontinued, the rash becomes evident as there is nothing to supress it, and so it stays, or gets worse until the next round of steroids causes it to disappear.   My son had this rash last winter.  It lasted for a few months and then disappeared.  The odd time when I notice it beginning,  I ensure that he drinks atleast 8oz of water every hour and have found that the rash subsides completely as long as he stays hydrated properly.  There is a hydration calculation that the hospital does when our kids are on IV's to ensure that they have enough water going through their system which is important in flushing out meds.  Once our kids go home, those levels are usually markedly decreased leading to the meds staying in the system and being recyled at a more concentrated level.  Therefore, it is very important to keep them well hydrated to prevent unnecessary side effects from the meds .

For anyone interested www.protopic.com  is one website where you may find more info on this cream which is used for moderate to severe eczema.  Like the steroid, it decreases the immune response, giving the appearance that the rash is going away, while the cause still persists.  It also has a warning on it that suggest a potential malignancy risk ,  so I would definately be careful before using on your child.  Also keep in mind that dermatologists in general have next to no experience with cancer patients (unless that is their focus) , never mind pediatric cancer cases.   Suppressing the rash does not mean it has been addressed.

My son has a ruch always a week after steroids, so, when steroids stop working, he has a rush (on his back and belly and under his eyes) until next month with steroids. For us doesn't work anything without steroids. We saw with dermatologist and he gave us 2 medication. First with steroids and secon no steroids. With steroids it's helped but I didn't use really often because rush it's not bother my son - thanks God!

I did not find any posts on this topic to be confrontational, and appreciate everyone's different perspectives.

It is absolutely true that steroidal creams thin the skin.   That is a well known side effect and your are fortunate that your doc was forthcoming enough with this information rather than prescribing it for your son.  As well, once the skin thins,  it also becomes more susceptible to other issues.   On top of this,  if supposedly an oral steroid is the cause of the rash, theoretically (which most likely it is not),  a topical steroid will only exacerbate the situation, as topical steroids are absorbed into the skin, circulating in the body much like oral ones, though at a reduced level.  So, really,  steroidal creams do not offer a solution but only a cover up of a symptom.

If one really wants to understand how quickly topicals get absorbed,  try rubbing a piece of crushed or minced garlic on the bottom of your feet;  within five minutes you will taste garlic ( a sulphur compound) in your mouth.