Stage 0: Abnormal cell changes occur in the top layer of the
skin. These cell changes are found in the melanocytes. This stage is
also referred to as melanoma in situ.
Stage I: The melanoma has grown, but not spread beyond the epidermis, the top layer of the skin.
Stage II: At this stage, the melanoma has spread down close to the subcutaneous tissue.
Stage III: It has now spread locally, particularly to the nearby lymph nodes. Some stage III melanomas may not be able to be removed by surgery.
Stage IV: Also called metastatic melanoma or advanced melanoma. The melanoma has spread to other organs in the body, most often the lungs, liver, brain, bone, or gastrointestinal tract. It may also spread to distant areas of the skin or distant lymph nodes.