What can be the cause/s of hump of the ribs underneath the breasts.other than scoliosis.?

Rib issues: There are deformities of the chest wall called pectus cavernosum or excavatum that may cause contour issues. Having a fracture or a rib problem may cause as well. Get an evaluation.

Sternal asymmetry: Your breast bone (sternum) can articulate with your ribs deeper, shallower, or in the center of your your rib cage. The former is called "pectus excavatum, " the next is called "pectus carinatum." both can cause the ribs to hump up in the chest. Both are innocuous. Check with your doctor for proper diagnosis and explanation.