1. Male breast complaints have increased in recent years, and it is therefore increasingly important for radiologists to be knowledgeable about imaging features of pathology that can occur in the male breast.2. Male breast pathology most commonly includes gynecomastia, and the chief differential consideration is male breast cancer. However, there are a number of other entities that can occur in the male breast of which radiologists should be aware, in order to perform adequate concordance of biopsy results with imaging findings.3. Male breast pathology can involve structures of the subcutaneous tissues, including skin, fat, muscle, blood vessels, lymphatics, and nerves. Alternatively, pathology can originate from ductal and stromal breast tissue in males, with lobular pathology being extremely rare given lack of progesterone-dependent lobular proliferation in males.

1. Male Breast Development and Important Differences from the Female Breast2. Gynecomastia (most common pathology) versus Male Breast Cancer3. Less Common But Important Male Breast Pathology and Imaging Findingsa. Skin - sebaceous/epidermal inclusion cystsb. Fat - lipoma and fat necrosisc. Muscle/Fascia - Desmoid tumord. Blood vessels/vascular tumors - vascular malformations, hemangioma, angiolipomae. Nerves - schwannomas, granular cell tumorsf. Lymphatics - intramammary lymph nodeg. Ductal tissue - intraductal papillomah. Stromal tissue - PASH, myofibroblastomai. Other - subareolar abscess, diabetic mastopathy