Harold Delf Gillies performed one of the first sexual reassignment surgeries, termed gender affirmation surgeries as of 2022, on record in 1946 in London, England. He also practiced modern plastic surgery and helped distinguish it as a new branch of medicine in London, England, starting in the early 1900s. Gillies’s work focused initially on facial reconstructive surgery, particularly during both World War I and World War II. Gillies created newer and more efficient techniques that later became standard procedures for reconstructive and cosmetic surgeries. Gillies, along with two members in his practice, standardized over 11,000 techniques, and beginning in 1946, he performed one of the first successful phalloplasties on a transgender man, where he formed a new penis from the patient’s existing skin and tissue.

Gender-affirming mastectomy is a type of surgery that removes breast tissue, tightens the skin, and can adjust nipple placement to provide the desired results of a more masculine-looking chest. Mastectomies started as a way for surgeons to remove breast cancer and tumors from the breast tissue. However, as of 2022, surgeons also use the procedure as a means of gender-affirming surgery for transgender and non-binary, hereafter TNB, individuals. If a person identifies as transgender, their gender identity differs from the sex they were assigned at birth and the gender they were most likely raised as, which can produce gender dysphoria, a condition that can last a lifetime. Non-binary individuals may have a similar experience, but they identify outside of or between the identifiers of man and woman. Gender-affirming mastectomy, sometimes called top surgery, improves the quality of life for people who seek the appearance of a masculine chest to both better integrate themselves into society and lessen the mental and emotional burden of gender dysphoria.