How is melanoma diagnosed?

You might have a number of tests to investigate your symptoms and confirm a diagnosis of melanoma, including: 

• medical history 
• physical examination of the skin for moles or other pigmented areas that look abnormal in size, shape, colour or texture 
• physical examination of lymph nodes to see if they are enlarged 
• dermatoscopy, where a light source and magnifying glass are used to see spots on the skin more clearly 
• biopsy, where a small sample of skin is removed to be examined under a microscope; this may involve 
• shave biopsy of the skin: the top layers of the skin are shaved off 
• punch biopsy of the skin: a deeper sample of skin is removed using a tool that punches through all the skin layers 
• incisional or excisional biopsy of the skin: a surgical knife (scalpel) is used to cut through all the skin layers and remove all the tumour (excisional) or part of the tumour (incisional) 
• biopsies of other areas of the body that the melanoma might have spread to: this might include a fine needle biopsy on an enlarged lymph node, where a thin needle is used to take a sample of cells that are checked for melanoma under a microscope.^[4] 

Staging

If you are diagnosed with melanoma, you might have more tests to determine the stage of the disease and whether the cancer has spread to other parts of the body. These can include imaging tests such as X-rays, computerised tomography (CT) scans or magnetic resonance imaging (MRI). Knowing the stage of the disease helps your medical team plan the best treatment for you. 

Melanoma is divided into 5 stages, depending on its thickness in the skin, and whether it has spread to nearby lymph nodes or other organs:^[5][6] 

• Stage 0 (melanoma in situ); less than 0.1 mm thick: the tumour is only in the epidermis and has not invaded the dermis. 
• Stage I; less than 2 mm thick: the tumour has not spread to the lymph vessels, lymph nodes or distant organs. This stage is divided into stages IA and IB, depending on the thickness of the tumour, how fast the tumour cells are dividing and whether the tumour is ulcerated. 
• Stage II; greater than 2 mm thick: the tumour has not spread to the lymph vessels, lymph nodes or distant organs, but it is thicker than in stage I. This stage is divided into stages IIA, IIB and IIC, depending on the thickness of the tumour and whether it is ulcerated. 
• Stage III: the tumour has spread to nearby lymph vessels, lymph nodes and/or skin. It has not spread to distant sites in the body. This stage is divided into stages IIIA, IIIB, IIIC and IIID, depending on whether the tumour is ulcerated, and the extent of growth into the lymph vessels, lymph nodes and nearby skin. 
• Stage IV: the tumour has spread to other organs (e.g. lungs, liver, brain, bone, soft tissue or gastrointestinal tract), to distant areas of the skin or subcutaneous tissue, or to distant lymph nodes. This is also called metastatic melanoma.