Diagnosis is the process of identifying a disease by its signs and symptoms.
If symptoms are present, the doctor will ask about your medical history and perform a physical exam. In addition the doctor may order various diagnostic tests. These may include laboratory tests and imaging procedures.
If a mass is present - a lump or bump under the skin - a biopsy may be necessary to determine whether cancer is present. A biopsy is a procedure to remove part of all of a mass so that it can be tested to determine if the cells are cancerous.