What Does A Rash Around The Nipples Indicate?

Hi, my 40 yr old husband noticed a rash around his nipple 2 days ago---I just found out, I'm pregnant, & very worried for him, my sister has brain cancer, & so I worry about cancer a lot. He will see a doctor tomorrow. But in the meantime,I'd appreciate your candid thoughts--I've survived cancer & just want to be realistic. His rash is sensitive, and begins @ the edge of his aereole on the outside (towards his armpit) & follows it in an arc, extending out for about 3/4 of an inch. The rash looks like hives--it's solid red, smoothe, dry and does NOT have any crustiness, discharge, or raised borders. However, I can feel underneath the rash a soft, moveable mass--not clearly defined like a lump (it doesn't feel like my fibroadenoma or cystic breasts, but I've got big lumps & very mystic breasts) , but it has the consistency more like a muscle. If it matters: he lives a clean life & is very healthy & active, although he's been working a lot & hasn't been able to play soccer for a couple months. I don't believe his rash/lump is related to an allergy or irritation from exercise or new detergent etc..., it doesn't apply. I would appreciate your thoughts on this condition, does it sound like cancer ? Regardless, he will s3e the doctor tomorrow. Thanks, so much ! Amanda