Melanoma in situ

A skin cancer doctor can diagnose melanoma by examining it closely with a dermoscope. It will usually have specific colours or structures that alert the doctor to the possibility of melanoma. Sometimes these clues to diagnosis are hard to see and the melanoma is suspected because of changed appearance in repeated dermoscopic photographs.⁴ When a melanoma is suspected, the doctor will surgically remove the suspicious spot (a procedure known as excision biopsy) so that a skin pathologist can examine the tissue and make a definitive diagnosis.

Treatment of melanoma

All melanomas must be surgically removed with a clear margin around the edge. In most cases, melanoma in situ must be removed with a clear margin of at least 5mm of normal skin around its outer edge.^5, 6 The initial excision biopsy is rarely this wide, so usually once a melanoma in situ is detected, a further excision must be performed to ensure a clearance of at least 5mm. If the melanoma is in a cosmetically sensitive area or if the function or movement of the area is likely to be affected, your skin cancer doctor may refer you to a plastic surgeon or the melanoma unit of a hospital for further treatment.

Learn more about excision and excision biopsy.

Follow-up: what happens next?

Further assessment

The risk of a melanoma in situ spreading to other parts of the body is extremely low, but your doctor will perform an examination for signs that the melanoma has spread. This examination involves:

• checking the lymph glands in the neck, armpits, groin and possibly behind the knees or elbows depending on the original site of the melanoma
• checking for enlargement of, or lumps in the liver or spleen
• If it has not yet been performed, your doctor should check the entire body for melanomas and other skin cancers elsewhere.

Specialist referral

In some circumstances, your doctor may refer you to another doctor or health service for further treatment or assessment. For example:

• A plastic surgeon can perform a wider excision of the melanoma to achieve a good cosmetic outcome or preserve function of the affected area
• A public hospital melanoma unit can offer a team approach where surgeons, dermatologists, skin pathologists and other specialties are involved in your care. Your doctor may refer you to a public hospital melanoma unit for further treatment, to get a second opinion on the initial skin pathologist’s report, or advice on future follow-up and treatment.

Further tests

There is no evidence that blood tests, x-rays, ultrasound, lymph node biopsy or MRI scanning is helpful in detecting spread of early melanoma or influencing outcomes.⁷

If the original melanoma returns, it is likely to be in the first 1-2 years after diagnosis.⁷ People who have had a melanoma have an increased risk – as much as 5 to 10 fold – of developing a new melanoma in future. This increased risk persists lifelong.⁸

High risk patients

Some people have an especially high risk of developing further melanomas in future. These people include:

• People who have already had more than one melanoma.
• People with a strong family history of melanoma.

Mole mapping (total body photography) is sometimes recommended for people in these high risk groups.¹⁰

Self-examination

Skin cancer self-examination is a very important part of ongoing care. In people with a previous melanoma, 75% of new melanomas are self-detected by the patient.¹¹

People with a history of melanoma should ideally check their own skin every 1-2 months.

Skin checks for your family

Melanoma tends to run in families. If you have had a melanoma, your first-degree relatives (children, sisters, brothers and parents) have an above-average chance of developing melanoma. They should check their own skin regularly and consider yearly skin checks by a doctor or nurse.

References

1. Warren L, Fuller K. Skin cancer – an Australian perspective, in ABC of Skin Cancer, eds Rajpar S, Marsden J. BMJ Books, Blackwell Publishing, 2008
2. Australian Institute of Health and Welfare. Skin cancer in Australia, 2016. 
3. McGuire ST, Secrest AM, Andrulonis R, Ferris LK. Surveillance of patients for early detection of melanoma: patterns in dermatologist vs patient discovery. Arch Dermatol. 2011;147(6):673–678, 2011.
4. Menzies S, Guitera P, Soyer P et al. What is the role of sequential digital dermoscopy imaging in melanoma diagnosis? Clinical practice guidelines for the diagnosis and management of melanoma, 2018. 
5. Sladden M, Nieweg O, Howle J et al. What are the recommended safety margins for radical excision of a primary melanoma (in situ)? Clinical practice guidelines for the diagnosis and management of melanoma, 2020. 
6. Sladden M, Nieweg O, Howle J et al. Updated evidence-based clinical practice guidelines for the diagnosis and management of melanoma: definitive excision margins for primary cutaneous melanoma. Medical Journal of Australia volume208 issue3, February 2018, pages 137-142, 2018.
7. Morton R, Barbour A, Bell C et al. What investigations should be performed following a diagnosis of primary cutaneous melanoma for asymptomatic stage I and stage II patients? Clinical practice guidelines for the diagnosis and management of melanoma, 2018. 
8. Barbour A, Guminski A, Liu W et al. Ideal settings, duration and frequency of follow-up for patients with melanoma. Clinical practice guidelines for the diagnosis and management of melanoma, 2019.
9. Trotter S, Sroa N, Winkelmann R et al. A global review of melanoma follow-up guidelines. J Clin Aesthet Dermatol. 2013 Sep; 6(9): 18–26, 2013.
10. Mann G, Cust A, Damian D et al. What interventions have been shown to provide clinical benefit in those assessed to be at high risk of new primary melanoma? Clinical practice guidelines for the diagnosis and management of melanoma, 2018.
11. Barbour A, Guminski A, Liu W et al. Follow up after initial definitive treatment for each stage of melanoma. Clinical practice guidelines for the diagnosis and management of melanoma, 2018.