Abnormalities on the chest wall

my mother recently had a routine mamogram (mammogram). They detected an abnormal mass on the chest wall, not in the actual breast.  She has just turned 47.  She quit smoking about a year ago (smoked approx 30 years).  her lung x-rays came back normal.  They ordered more pictures in the mamogram (mammogram) from different angle's and an ultra sound.  Can you please tell me if this is a normal finding, and what could this possibly be, other than cancer.

[CCF-RN,MSN-rf]

Dear jellybeanz:  This is not a normal finding but there are many possible explanations.  It makes sense to repeat the mammogram and do an ultrasound depending on the exact location.  Also, it might be valid to do a CT scan.  Sometimes this is a more precise test than a plain chest x-ray.