Individuals should seek medical advice if a mole or area of the skin begins to change. A medical examination and diagnostic testing can determine if a suspicious area is a melanoma or non-melanoma skin cancer, or some other skin condition.

The most common way for physicians to diagnose skin cancer is to biopsy the suspicious lesion. The removed specimen is sent to an experienced pathologist who views it under a microscope for evidence of cancer. The method of excision (removal) depends on the structure of the lesion. The physician will typically administer a local anesthetic to numb the affected area before performing the biopsy. The three main types of biopsy include:

• Shave. This type of biopsy is normally used for raised lesions, such as nodular basal cell carcinoma or squamous cell carcinoma. After a local anesthetic is applied to the area, the physician uses a surgical blade to shave off the top layers of the suspicious lesion.
  
  
• Punch. This type of biopsy is normally used for removing a flat, broad lesion. A punch biopsy removes a deep sample of skin. During this procedure, the physician rotates a tiny round tool that resembles a cookie cutter until it cuts through all the layers of the skin to extricate the questionable lesion or mole.
  
  
• Incisional or excisional biopsy. For a tumor that has grown into the deeper layers of the skin, a physician will often perform an incisional or excisional biopsy. An incisional biopsy removes a portion of the tumor to be examined later whereas an excisional biopsy removes the entire tumor. These biopsies can help determine whether the tumor is benign or malignant. Excisional biopsy is the recommended method for melanomas.