<s>[INST] my son had a small bubble under his tongue, he wouldnt leave it alone and now it is an ugly skin tag.  our pediatrician says its harmless but my son wants it removed, what is the medical term for it?  the doctor called it something starting with a "c" i think. [/INST] Hi. Welcome to Chat Doctor . I have gone through your query and can understand your concern.... As per your complaint a small bubble under the tongue can be due to a blocked duct of salivary gland leading to formation of a Mucous cyst also known as Muscle. It is true that it is harmless and will not cause any problem and will resolve gradually on it own. You can make him gargle with a concentrated salt water solution. In case if it does not resolve or continues to recur, then it ha to be removed surgically. Hope this information helps. Thanks and regards. Chat Doctor. . </s>