A chest scar from a mastectomy, a surgical procedure to remove all or part of a breast. Transgender men commonly undergo mastectomy (colloquially referred to as "top surgery" in LGBT circles) to achieve a more masculine appearance. It's also performed for the treatment of breast cancer and gynecomastia.
Mastectomy scars tend to come in symmetrically placed pairs, placed on lower chest, right below the pectorals. They are sometimes slightly curved upwards.
