Wiki recurrent mammary carcinoma of skin

[DebbiePottsEngland]

We need some help with a diagnosis code for the pathology reading of recurrent mammary carcinom of skin. the tissue was excised as skin from the mastectomy site. Should this be a secondary malignancy or a primary of the skin? I thought I remembered reading something that said if it is a recurrent malignancy, then it is primary but primary of breast is different than primary of skin.
Thanks in advance for your help.
Debbie in Dickson