thank you for posting your query in healthcaremagic.com.... well your child s disorder is known as pectus carinatum or pigeon chest.... see when all bones grow during growth spurt or adolescence, then the sternum and ribs can grow more to cause this deformity....sometimes, diseases like marfans, noonans, turner, osteogenesis imperfecta etc can be associated... generally it does not cause any symptoms except the protrusion.....and generally stays the same following growth spurt...but some severe cases can develop fatigue and respiratory distress.... treatment is required only in severe cases... options are external braces and surgery... hope this was useful... contact me for any further queries..... regards