Funny thing is I eat peanut butter all the time and kiss DS and he's never gotten a rash from that.
I know exactly what you mean - I said the same thing to Dylan's allergist after we got his scratch tests done. We knew that he was allergic to dairy, but had to test for several things (egg, citrus, mustard, dust mites) that we were unsure of. With peanut allergy being so prevalent, and with us going through the test anyway, I asked them to test for peanut at the same time. I was shocked when it came up positive, because I ate a TON of peanut butter while breastfeeding, and though I never gave it to him to eat, I wasn't *so* careful with washing my hands, kissing him, etc. after I did. Never had a problem (Now in retrospect, it's possible that his eczema flared, but his skin was so bad when he was young that I would never have connected it. And he never got hives or swelling like he does with his other allergies)
I was so surprised that the allergist then suggested running blood tests to confirm. He mentioned that children with eczema have such sensitive skin that they can get false positive results on a scratch test. The threshold they place for an allergy is anything greater than 0.35 - Dylan gets hives and swelling on contact with dairy, and his dairy result was 0.8. His peanut result was over
12 I was stunned, to say the least.
Re: the other nuts, you're right that they are different families - peanuts are a legume, where pine nuts, cashews, pistachios, almonds, etc. all fall under the category of tree nuts. I've done some research as I was concerned about the same thing. I've seen estimates that range from 30-60% of children with a peanut allergy will also develop a tree nut allergy. I've decided to keep all nuts out of Dylan's diet for the time being, but he's never ingested any - given that your lo has already had pine nuts without problem, he may be less at risk. But while some people are allergic to the entire tree nut family, others may only be allergic to one, like hazelnuts for example. At the very least, I would keep nuts out of his diet until you get the chance to speak to his doctor about it. Nuts are really quite easy to avoid since they are so clearly labeled, and then you can get his take on it.
hth