I would definitely go for the MRI. That is a good next step to see how extensive it is and to see what they get to work with. You want to make sure it is a lymphatic malformation vs another type of malformation. There are vascular malformations, or other tissue malformations. It looks to be cavernous, which is somewhat good as it is less likely to get infected(vs it being more on the skin). I know it can be hard to see your child going under GA(my mom gets teary eyes talking about it), but he is over the age of 1 which will lessen his possibilities for complications. There are children who go under GA at younger ages.
Who are you taking him to? Does the doctor have experience with the condition? It's important that the doctor has treated the condition before. Experience is a must. The doctor will probably book him for surgery.. or you can look into injections(sclerotherapy). I would look at other options before going for surgery. Sclerotherapy works well for macro-cystic lymphatic malformations. If it's micro-cystic, then it's harder to treat. There is also the OK-432 injection, though I'm not sure who you can go to for that.
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