Breast Cancer Suspicion in a Transgender Male-to-Female Patient on Hormone Replacement Therapy Presenting with Right Breast Mass: Breast Cancer Risk Assessment and Presentation of a Rare Lesion.

There has been an increasing use of hormonal therapy among male-to-female (MtF) transgender individuals. This long-term hormone replacement therapy (HRT) renders MtF individuals a unique patient subgroup in terms of breast cancer risk. This case describes a MtF transgender who presented with a breast lesion concerning for malignancy following hormonal replacement therapy. The patient additionally had a strong family history of breast cancer. Final pathology revealed lobular hyperplasia in the setting of gynecomastia and pseudoangiomatous stromal hyperplasia (PASH). Both pathology findings are rare in biological females, let alone in the setting of hormone replacement therapy in a MtF individual. While the number of reported cases of suspicious breast lesions in this population remains scarce, it presents both a diagnostic and therapeutic challenge due to the nature of the treatment course and the lack of research in this recently growing subgroup of patients.