Imaging characteristics of malignant lesions of the male breast.

Most men referred for breast imaging have palpable lumps, breast enlargement, or tenderness. Most of the evaluated lesions are benign. Male breast cancer accounts for less than 1% of total male breast lesions. Differentiation between benign and malignant masses is critical because it alleviates patient anxiety and allows unnecessary procedures to be avoided. Clinically suspicious lesions referred for imaging should first be evaluated with mammography. In patients with questionable findings at mammography and for lesions that are difficult to image with mammography, ultrasonography (US) is often useful for further characterization. A discrete mass at mammography or US is suspicious for malignancy. The relationship of the mass to the nipple should be carefully assessed; an eccentric location is highly suspicious for cancer. Secondary signs occur earlier in male patients because of smaller breast size. Such signs include nipple retraction, skin ulceration or thickening, increased breast trabeculation, and axillary adenopathy. US of the axillary region is helpful for staging. At pathologic analysis, cystic lesions commonly demonstrate malignant findings; therefore, all cysts and complex masses should be worked up as potentially malignant lesions. Benign conditions that may mimic male breast cancer include gynecomastia, lipoma, epidermal inclusion cyst, pseudoangiomatous stromal hyperplasia, and intraductal papilloma.