white rings on skin on upper body

I recently went through chemo therapy last year for breast cancer, and just recently about 3 months ago, I noticed a white ring larger then a silver dollar it looks like someone took a milk cap and stuck it on my skin and left a white ring first I noticed one and a few weeks later I have 5 total rings, one on upper back and one upper front shoulder, two on side of ribs and one lower back all on the left side.  I did start taking a new hair skin and nail vitamin could this cause the discoloring of my skin.

[Bhupinder Kaur, MD]

Hello,
These rings can be due to pityriasis versicolor, nummular dermatitis or pityriasis rosea. Nummular dermatitis is a sort of eczema and needs to be evaluated because it is itchy. It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.