Pathologic Evaluation of Breast Tissue From Transmasculine Individuals Undergoing Gender-Affirming Chest Masculinization.

[CONTEXT.—] Bilateral mastectomy for chest masculinization is one of the gender-affirming procedures for transmasculine individuals.

[OBJECTIVE.—] To optimize gross handling protocols and assess histopathologic findings in transmasculine breast tissue specimens.

[DESIGN.—] We identified all gender-affirming mastectomies from 2015 to 2018. We sequentially identified reduction mammoplasty (RM) cases for macromastia from the same period as control. Significant findings were defined as atypical ductal or lobular hyperplasia (ADH, ALH), ductal or lobular carcinoma in situ (DCIS, LCIS), or invasive carcinoma.

[RESULTS.—] Significant findings were present in 6 of 211 gender-affirming mastectomies (2.8%) as follows: ADH (n = 5) and LCIS together with ALH (n = 1). By comparison, 19 of 273 RM specimens (7%) yielded significant findings as follows: ALH (n = 11), ADH (n = 4), LCIS (n = 2), DCIS (n = 1), and invasive lobular carcinoma (n = 1). In the gender-affirming group, 142 transmen underwent androgen therapy before surgery, of whom 2 had significant pathologic findings. Thirty and 41 individuals had a family history of breast cancer in the gender-affirming and RM group, of whom 1 and 3 individuals had significant pathologic findings, respectively.

[CONCLUSIONS.—] Our study demonstrates that we handle transmasculine mastectomy specimens by examining 2.8 times more slides on average than for RMs, with a 2.5 times lower rate of significant pathologic findings. Prior family history of breast cancer or the use of androgen therapy before surgery in gender-affirming individuals did not increase the risk of identifying significant breast lesions. We recommend submitting 4 tissue blocks per mastectomy for individuals undergoing gender-affirming breast surgery.