Does Facebook allow post-mastectomy photos?

Yes. Facebook agrees that undergoing a mastectomy is a life-changing experience and that sharing photos can help raise awareness about breast cancer and support the men and women facing a diagnosis, undergoing treatment or living with the scars of cancer. The vast majority of these kinds of photos are compliant with Facebook policies.

Source: https://www.facebook.com/help/318612434939348?helpref=uf_permalink