E5470. Moving Beyond Gynecomastia: Pictorial Review of Less Common Benign and Malignant Findings in the Male Breast
  1. Anahita Tavana; Mayo Clinic Florida
  2. Neema Patel; Mayo Clinic Florida
  3. Shahrzad Tavana; University Hospitals Cleveland Medical Center, Case Western School of Medicine
  4. Haley Letter; Mayo Clinic Florida
Most breast symptoms in men occur secondary to benign conditions, with gynecomastia being the most common etiology. Male breast cancer is rare, with invasive ductal carcinoma (IDC) being the most common subtype. There are certain mammographic features that should raise suspicion for causes other than gynecomastia and warrant further workup.

Educational Goals / Teaching Points
This exhibit aims to review imaging findings of common and less common male breast pathologies and describe key mammographic findings that suggest diagnoses other than gynecomastia using interactive cases.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
According to the American College of Radiology (ACR) Appropriateness Criteria, diagnostic mammography is the recommended initial imaging modality in men aged 25 or older, who present with an indeterminate palpable breast mass. Gynecomastia is the most common cause of breast lump, pain, or enlargement in men and has several potential mammographic appearances, but is most often flame-shaped, asymmetric, and always centered behind the nipple. Findings that should raise suspicion for etiologies other than gynecomastia include mass eccentric to the nipple, lymphadenopathy, calcifications, and architectural distortion. In the presence of suspicious findings, ultrasound and likely image-guided biopsy are the recommended next steps. Some of the other benign causes of a palpable breast mass include lipoma, pseudogynecomastia, fat necrosis, abscesses, and less commonly cysts. As for malignant causes, IDC is the most common subtype of male breast cancer. Ductal carcinoma in situ (DCIS) is the second most common subtype and often presents as pleomorphic grouped or pleomorphic segmental microcalcifications. Lobular pathologies are rare due to presence of minimal stromal tissue (i.e., lobules) in the male breast. Other rare causes include metastatic disease and primary breast lymphoma.

Location is key to diagnosing gynecomastia. Any mass eccentric to the nipple should be further evaluated with ultrasound. Ominous features that raise suspicion and prompt biopsy include distortion, adenopathy, and calcifications that are not definitely benign.