Male Breast Disease: What the Radiologist Needs to Know.

The male breast is susceptible to a variety of benign and malignant processes, many of which clinically present as a palpable finding, focal pain, or breast enlargement. Gynecomastia is the most common abnormality in the male breast and must be distinguished from malignancy. Imaging of the symptomatic male breast begins with a diagnostic mammogram in a patient ≥25 years and targeted ultrasound in a patient <25 years. If the breast finding is incompletely imaged or occult at mammography, targeted ultrasound must be performed. Similarly, if the breast finding is suspicious at targeted ultrasound in a younger patient, mammography must be performed. After a complete diagnostic evaluation, suspicious findings require biopsy because of overlap in clinical and imaging features of benign and malignant pathologies. Although no breast cancer screening program exists for men due to the <1% incidence of breast cancer, transgender male to female patients >50 years and treated with exogenous hormone therapy for >5 years should undergo breast cancer screening. This paper will review the anatomy of the male breast, appropriate imaging of the symptomatic male breast, gynecomastia and other benign conditions, and male breast cancer and other malignant conditions. Finally, we will discuss imaging of the transgender patient.