Diagnosing Merkel cell carcinoma begins with a physical examination so that your doctor can evaluate the symptoms you are experiencing. Your doctor may also feel for bumps on nearby lymph nodes, which can indicate that the cancer has spread. Other types of testing and imaging scans may be necessary to make a definitive diagnosis. Additional information to confirm a diagnosis and how advanced the disease is can be obtained through more in depth examination of the skin. The doctor may perform a skin biopsy to remove all or part of the affected area(s) for examination under a microscope to look for any precancerous or cancerous cells. Sometimes a biopsy will remove all or part of the tumor.