Breast cancer in men is extremely uncommon. It accounts for <1,500 of the more than 180,000 breast cancers diagnosed in the United States each year. Just as with women, the prognosis for men is related to the size of the cancer and its stage (axillary lymph node status) at the time of diagnosis. The most frequent reason for imaging the male breast, is the clinical detection of an asymmetric thickening or a mass. The breast may be enlarged, and there may be associated pain or tenderness. Standard mammographic projections can be obtained in males. The normal male breast reveals a small nipple, and there is only subcutaneous fat visible in the subareolar region. This is almost always caused by asymmetric gynecomastia. Even when gynecomastia is asymmetric, it is usually evident by mammography, to a lesser degree, in the contralateral breast. Histologically, the normal male breast contains subareolar ducts similar to those found in prepubertal girls. When stimulated, the ducts may elongate and branch, but lobule formation is extremely rare. This accounts for the fact that lesions of the lobule (e.g., fibroadenomas) found in women do not occur in men. Cysts may develop, but they too, are rare in men. It is unclear whether cysts in men are lobular dilatation or cystically dilated ducts. Because the male breast contains ductal epithelium, ductal carcinoma can develop. Gynecomastia does not appear to increase the risk of cancer, although significant exposure to ionizing radiation does, and there is an increased incidence in those with Klinefelter’s syndrome. The mean age at which men develop breast cancer is approximately 5 to 10 years later than for women. Most male breast cancers are detected as a result of palpable masses (80% to 90%). Nipple changes are not uncommon, and in 5% to 10% nipple retraction or discharge, or both, occurs. As with women, the discharge may be serous or sanguineous. Skin ulceration does not occur with gynecomastia and is a grave sign in male breast cancer. Most male breast cancers are infiltrating ductal tumors, with approximately 10% detected while still intraductal. Paget’s disease of the nipple has been reported. Because lobule formation is rare in men, infiltrating lobular cancers are uncommon. Histologically, male breast cancer is indistinguishable from cancers of the female breast, and all ductal subtypes have been described. Unlike gynecomastia, most male cancers are eccentrically located and occur away from the subareolar region, although occasionally they may develop immediately under the nipple, while virtually all cases of gynecomastia produce density fanning back and are centered on the nipple. Recognition of the characteristic distribution of gynecomastia and the usual eccentric growth of breast cancer will reduce the possibility of mistaking one for the other. The appearance of breast cancer in men is similar to that seen in women. Although male cancers more frequently tend to have lobulated margins, they may be spiculated or ill defined. Even intracystic cancer can be seen in men. Ductal carcinoma in situ (DCIS) can be found in males, and microcalcifications can occur. Skin calcifications are common in men and should not be mistaken for intraductal deposits. As with women, mammography does not exclude cancer, and false-negative mammograms can occur when concurrent dense gynecomastia is present. The treatment depends upon the stage of the disease. Surgery forms the first line of defence and is generally used. Stages I and II are locally operable and are generally treated by modified radical mastectomy. More advanced disease may require radical mastectomy, or may be treated with a lesser procedure coupled with radiation and/or chemotherapy. After surgery, the decision to proceed with chemotherapy or radiation depends upon the precise stage of the disease. Additionally treatment may include hormonal therapy as an adjuvant.

0.3

Breast and Mammography

Neoplasm, carcinoma

breast cancer
DCIS

Kopans D.B., Breast Imaging, 2nd edition on CD-ROM, Chap. 18, The male breast. National Cancer Institute: www.nci.nih.gov; The treatment of male breast cancer.