The etiology of the pectus deformity is not precise.The most accepted theory is the over-growth of the cartilage ribs as a response to the non-identified inducers.Ricets ,the pressure in the mother's womb or the diaphragma abnormalities might be responsible for the pectus excavatum etiology by inducing sternal traction.Genetic factors might also be effective as etiological factors as well.One of the three patients have pectus deformity in family history.Moreover in one of every five patients have scoliosis in family history.

 

Especially the inferior cartilage ribs are deformated and these ribs grow introverted in pectus  excavatum deformity and extroverted in pectus carinatum deformity.Also,the deformity might be symetric and asymetric. Through the examination of the cartilages resected in the surgical procedure ,vacuolization,aseptic necrosis areas and deformity in the cartilage cell row is observed.