Skin metastases occur as a spread from another cancer source. There are also primary skin cancers brought about by too much UV exposure.
The reason I asked is that I have a small raised red spot that I have had for couple of weeks. I dont' have any other signs of cancer and was concerned as the spot is similar to the illustration of skin mets only not severe (one small raised spot). From your reply I understand that the skin metasases occurs after treatment and cannot just occur independant of cancer.
Skin metastases from breast cancer usually occurs around the site or area of the previous surgery of breast cancer. Breast cancer cells can indeed metastasize to the skin overlying the breast. This also may be considered as a local recurrence of the breast cancer.
Treatment would usually consist of radiation (if the area is not yet previously radiated) or chemotherapy. This is usually diagnosed in a patient with previous breast cancer presenting with skin discoloration or nodules overlying the area of previous surgery. Biopsy is needed to confirm the diagnosis.