Diagnosing diseases by looking at single cells and small clusters of cells is called cytology or cytopathology. . The human body is made up of millions of cells and these can be sampled and looked at under the microscope, after suitable preparation, to help diagnose medical conditions. 

When a lump, or a bump is discovered in superficial areas of the body such as the breast and neck, a test known as Fine Needle Aspiration Cytology (FNAC) is recommended to determine whether the lump is cancer. This procedure is also used to test for thyroid, salivary glands and lymph nodes illnesses.