This is a medical question of type : exams and tests 
 How to diagnose Male Breast Cancer ? 
 Tests that examine the breasts are used to detect (find) and diagnose breast cancer in men.
                    The following tests and procedures may be used:         -   Physical exam and history : An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patients health habits and past illnesses and treatments will also be taken.    -   Clinical breast exam (CBE): An exam of the breast by a doctor or other health professional. The doctor will carefully feel the breasts and under the arms for lumps or anything else that seems unusual.     -   Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. The picture can be printed to be looked at later.    -    MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).    -   Blood chemistry studies : A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease.    -   Biopsy : The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. The following are different types of biopsies:                -  Fine-needle aspiration (FNA) biopsy : The removal of tissue or fluid using a thin needle.       -  Core biopsy : The removal of tissue using a wide needle.      -  Excisional biopsy : The removal of an entire lump of tissue.
                
                
                    If cancer is found, tests are done to study the cancer cells.
                    Decisions about the best treatment are based on the results of these tests. The tests give information about:         - How quickly the cancer may grow.    - How likely it is that the cancer will spread through the body.    - How well certain treatments might work.    - How likely the cancer is to recur (come back).        Tests include the following:         -   Estrogen and progesterone receptor test : A test to measure the amount of estrogen and progesterone (hormones) receptors in cancer tissue. If cancer is found in the breast, tissue from the tumor is checked in the laboratory to find out whether estrogen and progesterone could affect the way cancer grows. The test results show whether hormone therapy may stop the cancer from growing.    -   HER2 test: A test to measure the amount of HER2 in cancer tissue. HER2 is a growth factor protein that sends growth signals to cells. When cancer forms, the cells may make too much of the protein, causing more cancer cells to grow. If cancer is found in the breast, tissue from the tumor is checked in the laboratory to find out if there is too much HER2 in the cells. The test results show whether monoclonal antibody therapy may stop the cancer from growing.