Poland syndrome is a defect that affects your chest and hand on one side. From what ive experienced/seen, most people have one hand smaller than another (similar to nemos lucky fin),
And are usually born without a pectoral muscle. It can be pectoral minor, or it can be pectoral major, or like in my case, it can be both. The only treatments that is possible, is a prosthetic pectoral implant. As for the affected hand, thats something you have to learn to love.