Snapshot A 66-year-old man presents to his primary care physician for a routine check-up. He states that he has felt well and has no issues but mentions that he has felt a small lump in his chest under his left nipple. On physical examination, the physician notices that the patient has gynecomastia and palpates a firm, non-tender mass in the subareolar region of his left breast. No lymph nodes are palpable in the axilla. A mammogram is obtained and shows the finding seen in the image. Introduction Overview breast cancer in males is similar to that in females with regards to the pathophysiology, diagnosis, and treatment but is more rare Epidemiology Incidence < 1% of all breast cancers diagnosed per year < 0.5% of all cancer diagnoses in men in the US Demographics average age of presentation ~65 years ↑ incidence with age Risk factors age family history of breast cancer positive in ~30% of cases Klinefelter syndrome (XXY) strongest risk factor gynecomastia exogenous estrogen or testosterone use radiation exposure ETIOLOGY Pathophysiology nearly all cases are ductal carcinoma environmental and genetic risk factors may be associated with the development of male breast cancers (see above) Presentation Symptoms painless lump in the breast skin changes Physical exam painless lump in the breast 75% in the subareolar region nipple involvement more common than in women axillary lymphadenopathy Imaging Mammogram indications distinguish between malignancy and gynecomastia findings microcalcifications spiculate margins around an increased density Studies Biopsy core needle biopsy indications definitive histologic diagnosis distinguish between in situ versus invasive cancer findings majority of cases have infiltrating ductal carcinoma histology Differential Gynecomastia key distinguishing factors typically bilateral and symmetric breast enlargement no skin changes or axillary lymphadenopathy Breast abscess key distinguishing factor localized and painful inflammation, often with systemic symptoms (i.e., fever and malaise) Lipoma key distinguishing factor ovoid mass of fat Treatment Surgical simple mastectomy management of choice in early-stage disease cases Medical tamoxifen use as adjuvant chemotherapy in patients with locally advanced disease radiation therapy for patients who undergo breast-conserving surgery and patients treated with mastectomy and found to have involved lymph nodes on final pathology Prognosis 5-year mortality - ~8% Worse prognosis compared with women with breast cancer Similar to breast cancer in women, tumor size and the presence of lymph node metastasis are the most important prognostic factors often not detected until late in its course > 40% of patients have stage 3 or 4 disease at diagnosis