This is a medical question of type : exams and tests 
 How to diagnose Metastatic Squamous Neck Cancer with Occult Primary ? 
 Tests that examine the tissues of the neck, respiratory tract, and upper part of the digestive tract are used to detect (find) and diagnose metastatic squamous neck cancer and the primary tumor. Tests will include checking for a primary tumor in the organs and tissues of the respiratory tract (part of the trachea), the upper part of the digestive tract (including the lips, mouth, tongue, nose, throat, vocal cords, and part of the esophagus), and the genitourinary system.    The following procedures may be used:          -   Physical exam and history : An exam of the body, especially the head and neck, to check general signs of health. This includes 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.    -   Biopsy : The removal of cells or tissues so they can be viewed under a microscope by a pathologist or tested in the laboratory to check for signs of cancer.  Three types of biopsy may be done:               -  Fine-needle aspiration (FNA) biopsy : The removal of tissue or fluid using a thin needle.      -  Core needle biopsy : The removal of tissue using a wide needle.       -  Excisional biopsy : The removal of an entire lump of tissue.            The following procedures are used to remove samples of cells or tissue:               - Tonsillectomy: Surgery to remove both tonsils.      -  Endoscopy : A procedure to look at organs and tissues inside the body to check for abnormal areas. An endoscope is inserted through an incision (cut) in the skin or opening in the body, such as the mouth or nose. An endoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove abnormal tissue or lymph node samples, which are checked under a microscope for signs of disease. The nose, throat, back of the tongue, esophagus, stomach, voice box, windpipe, and large airways will be checked.           One or more of the following laboratory tests may be done to study the tissue samples:                -  Immunohistochemistry : A test that uses antibodies to check for certain antigens in a sample of blood or bone marrow. The antibody is usually linked to a radioactive substance or a dye that causes the tissue to light up under a microscope. This type of test may be used to tell the difference between different types of cancer.      -  Light and electron microscopy : A test in which cells in a sample of tissue are viewed under regular and high-powered microscopes to look for certain changes in the cells.      -  Epstein-Barr virus (EBV) and human papillomavirus (HPV) test: A test that checks the cells in a sample of tissue for EBV and HPV DNA.             -   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).    -   CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.    -   PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do. A whole body PET scan and a CT scan are done at the same time to look for where the cancer first formed. If there is any cancer, this increases the chance that it will be found.        A diagnosis of occult primary tumor is made if the primary tumor is not found during testing or treatment.