A melanoma diagnosis can make every unfamiliar medical term feel urgent. This melanoma staging guide explains the language doctors use after a biopsy, what each stage means, and why staging helps shape the next decision. It cannot replace advice from your treating team, but knowledge can help you ask clear questions and act without delay.
Melanoma is one of Australia’s most serious skin cancers because it can spread beyond the skin. When found early, it is often treated successfully with surgery. The purpose of staging is to establish how far the melanoma has progressed at the time of diagnosis – not to assign blame or predict one person’s future with certainty.
What melanoma staging measures
Doctors usually use the AJCC TNM staging system. It brings together three pieces of information: the features of the original melanoma, whether it has reached nearby lymph nodes, and whether it has spread to distant parts of the body.
The first part is the primary tumour. Your pathology report will usually state the melanoma’s Breslow thickness, measured in millimetres from the surface of the skin to the deepest melanoma cells. Thickness is one of the most significant factors in early melanoma staging. In general, a thinner melanoma has a lower risk of spread than a thicker one.
The report also records whether there is ulceration. This means the skin over the melanoma has broken down under the microscope. Ulceration can indicate a higher-risk melanoma at the same thickness. Other details, including the exact melanoma subtype and whether the biopsy margins are clear, can guide treatment planning, although they do not all determine the stage.
The second part is lymph node involvement. Lymph nodes are small immune-system glands found throughout the body, including in the neck, armpits and groin. Melanoma cells can travel first to nearby nodes. The third part is distant spread, meaning melanoma is found in organs or skin sites away from the original melanoma.
Melanoma staging guide: stages 0 to IV
The stage is usually confirmed after the initial excision and, where needed, further surgery or tests. Stages have subgroups such as IA, IB or IIIC. These subgroups matter, so a person should always ask their specialist for their full stage rather than relying on a broad label alone.
Stage 0: melanoma in situ
Stage 0 means melanoma cells are confined to the top layer of the skin, the epidermis. They have not grown deeper into the skin and cannot spread elsewhere at this point.
Treatment is generally surgical removal with an appropriate margin of surrounding skin. This is still melanoma and needs proper treatment, but stage 0 has an excellent outlook after complete removal. Lentigo maligna, a common type seen on chronically sun-exposed skin of the face in older Australians, is often stage 0 when diagnosed.
Stage I: thin, localised melanoma
Stage I melanoma has grown into the skin but remains localised. It is generally thinner and has no evidence of spread to lymph nodes or distant sites. Whether it is stage IA or IB depends mainly on thickness and ulceration.
The usual treatment is a wider excision around the biopsy site. For some melanomas, especially those approaching or exceeding 0.8 mm thick or showing ulceration, the treating team may discuss a sentinel lymph node biopsy. This is a procedure to check the first lymph node or nodes most likely to receive cells from the melanoma.
Not everyone with stage I melanoma needs this procedure. The decision depends on the pathology, the likely benefit of the result, possible complications and a person’s overall health.
Stage II: thicker melanoma, still localised
Stage II melanoma has not been found in lymph nodes or distant organs, but it has features associated with a higher chance of recurrence than stage I. It is usually thicker, ulcerated, or both. Stages IIA, IIB and IIC reflect increasing risk based on these tumour features.
Surgery remains the main treatment. A sentinel lymph node biopsy may be recommended to look for microscopic spread that cannot be felt during an examination or seen on a scan. Some people with higher-risk stage II melanoma may also be offered additional treatment after surgery, known as adjuvant therapy, to reduce the risk of melanoma returning. The right option depends on the individual and should be discussed with a melanoma specialist.
Stage III: melanoma in nearby lymph nodes or skin pathways
Stage III means melanoma has spread beyond the original site to nearby lymph nodes, or to small deposits in the skin or lymphatic channels between the primary melanoma and the local lymph node area. These deposits may be found on sentinel node biopsy, during a clinical examination, or in tissue removed after enlarged nodes are investigated.
Stage III is a broad category. A tiny amount of melanoma detected only under a microscope is different from disease in several enlarged nodes, so the substage is particularly relevant. Treatment may involve surgery, medicine such as immunotherapy or targeted therapy for melanomas with specific gene changes, and regular surveillance. Your multidisciplinary care team will consider the location, extent of disease, pathology results and your general health.
Stage IV: melanoma that has spread to distant sites
Stage IV melanoma has spread to distant skin or lymph node sites, or to organs such as the lungs, liver, brain, bones or bowel. Scans and blood tests may be used to define where melanoma is present and support treatment planning.
This stage requires specialist care, but it is not a reason to assume there are no options. Immunotherapy, targeted therapies, surgery in selected situations, radiotherapy and clinical trials have changed treatment for many people with advanced melanoma. Outcomes vary widely according to where the melanoma has spread, tumour biology, response to treatment and a person’s health.
How doctors confirm the stage
A suspicious spot is usually assessed with a full-thickness excision biopsy, where possible. Removing the whole lesion allows a pathologist to measure Breslow thickness accurately and check for ulceration. A partial biopsy can sometimes be necessary for a large lesion or one in a difficult location, but it may not show the deepest point of the melanoma.
After diagnosis, the next step may be a wider local excision to remove additional normal-looking skin around the biopsy scar. Depending on the melanoma’s features, your doctor may recommend a sentinel lymph node biopsy, ultrasound, CT, PET or MRI scans. Scans are not routinely needed for every thin, early melanoma because they can produce false alarms as well as useful findings.
Staging can occasionally change after further surgery or testing. That does not mean the first doctor got it wrong. It means the team has obtained more complete information.
Questions worth taking to your appointment
A pathology report can be technical. Ask your doctor to explain your Breslow thickness, whether ulceration was present, whether the melanoma was completely removed in the biopsy, and your final AJCC stage. It is also reasonable to ask whether a sentinel lymph node biopsy is recommended, what follow-up schedule you need, and whether family members should have skin checks.
Keep copies of your pathology reports and treatment summaries. If you see different doctors over time, these records make it easier to provide an accurate history.
Stage does not replace ongoing skin checks
After melanoma treatment, regular follow-up is essential. The schedule depends on your stage and personal risk, but review appointments commonly include examination of the scar, nearby lymph nodes and the rest of your skin. Your clinician may also teach you how to check your own skin between visits.
A new or changing spot should not wait for the next scheduled review. Look for a mole that changes in size, shape or colour, a lesion that looks different from the rest, or a sore that does not heal. Melanoma can occur anywhere, including the scalp, soles of the feet, under nails and areas that receive little sun. People with skin of colour can develop melanoma too, sometimes in less sun-exposed sites where changes may be missed.
If you have noticed a concerning lesion, arrange a prompt skin check with a qualified clinician. Every minute counts when a melanoma is changing, and early assessment gives you the clearest path to answers and treatment.