Clinicopathological findings in female-to-male gender-affirming breast surgery.

ABSTRACT

AIMS: Gender dysphoria is a diagnosis whereby an individual identifies as the opposite gender. The management of patients seeking female-to-male (FTM) transition includes hormonal therapy and surgical intervention, including mastectomy. The aim of this study was to characterize the immunohistological findings in resection specimens from FTM patients. METHODS AND RESULTS: We reviewed 68 cases (67 patients, one with re-excision) of FTM breast tissue resection by collecting clinical data, reviewing breast imaging and pathology reports (gross fibrous density, specimen weight, and number of cassettes submitted), and reviewing pathology slides [number of tissue pieces submitted, number of terminal duct lobule units (TDLUs), and the presence of histological findings]. Significant histological findings were present in 51 of 68 (75.0%) cases, including one case (1.5%) of flat epithelial atypia. Fibrocystic changes were the most common finding (27/68, 39.7%), followed by gynaecomastoid change, fibrotic stage, (22/68, 32.4%), and fibroadenomatoid change (11/68, 16.2%). Fibrocystic change was associated with increased numbers of TDLUs, and gynaecomastoid change was associated with lower body mass index and decreased numbers of TDLUs. Gynaecomastoid change showed a moderate proportion of luminal epithelial cells with strong-intensity immunohistochemical staining for oestrogen receptor, progesterone receptor, and androgen receptor, and a three-layered epithelium demonstrated by the use of cytokeratin 5/6 immunohistochemistry. CONCLUSIONS: We identified gynaecomastoid change at a significantly higher rate than previously reported in female patients. We support the continued gross and histological evaluation of FTM specimens in light of the identification of atypia in one case.