Hi and thanks for the query, Its very important to consider other symptoms experienced by the child. Is the child having fever or has a bad general outlook. Collection of pus, no matter where it is found in the body has to be drained. The fear is persistence of the pus might easily spread in blood to attack other body structures. I suggest the child gets examined by her general physician to have an appraisal of her general outlook. If its actually pus collection, this is usually accompanied by tenderness, redness and at times low grade fever. Your doctor might decide to incise, drain the pus and prescribe anti biotics if necessary. In case its a keloid, the opinion of a dermatologist. However, its better to see your primary care physician first. Thanks and hope this helps. Thanks and best regards, Luchuo, MD.