A lump above the belly button is a common sign of an umbilical hernia, according to WebMD. Umbilical hernias can develop in infants and adults and are caused by fluids, fat or intestinal tissues that press through weakened areas in the abdominal wall.
Umbilical hernias in infants typically resolve on their own within three to four years, according to MedlinePlus. Adult umbilical hernias are treatable with surgery.
During an umbilical repair procedure, a cut is made into the abdomen, and the protruding intestinal contents are moved back inside the abdomen, states MedlinePlus. Once the bulging tissues are correctly adjusted, the weakened abdominal areas are stitched and repaired. In certain cases, mesh material may be placed on top of the weak spot to strengthen the tissue.