Melanoma is a skin cancer where there is uncontrolled, cancerous growth of pigment cells. They have the ability to spread to other parts of the body, making this one of the most dangerous skin cancers.
Melanomas may present as a new lesion in normal looking skin (75% of melanomas), or as an existing mole that undergo change. Patients may notice that they change in colour, size and shape with an irregular outline in more than one colour. They may appear on any body area and may even include sun-unexposed areas.
The main risk factors for developing melanoma include:
- White skin that burns easily
- Previous skin cancers
- Many moles
- Multiple (>5) atypical moles
- Strong family history of melanoma
Clinical features of melanoma
Most melanomas have characteristics described by the ABCDE’s of melanoma. The most common site in men is the back and in women is the leg.
The ABCDEs of Melanoma
B. Border irregular
C. Colour variation
D. Diameter >6mm
E. Evolving (enlarge, change)
Melanomas may have different characteristics:
- They may have a variety of colours
- They may have no pigment
- They can be itchy, tender and may bleed
- They may be flat (during the horizontal growth phase)
- They may become raised (during the vertical growth phase)
How is melanoma diagnosed
- History of change, a clinical suspicion and dermoscopy
- Histology: Excised lesion with a narrow margin
Terminology used by dermatologists
- In situ means - that the tumour is confined to the epidermis
- Invasive means – that the tumour has spread into the dermis
- Metastatic means – that the tumour has spread to other tissues
How is melanoma managed?
- Treatment of an in situ melanoma: Surgery and regular dermatology follow-up
- Treatment of invasive melanoma: is discussed at a combined discussion between patient, oncology surgeon, oncologist and dermatologist.
- Following confirmation of the diagnosis, wide localexcision is carried out at the site of the primary melanoma. The extent of surgery depends on the thickness of the melanoma and its site.
- If lymph nodes are not enlarged, they may be tested to see if there is microscopic spread of melanoma (sentinel node biopsy).
- Melanoma staging means finding out if the melanoma has spread from its original site in the skin.
- Blood tests and Imaging performed in invasive tumours
What happens next?
- Self skin examination
- Follow-up intervals are based on the staging of the patient:
- six-monthly for five years for patients with stage 1 disease
- four-monthly for five years for patients with stage 2 or 3 disease
- yearly thereafter for all patients.
- AIMS to detect recurrences and new primary melanomas early
- Check regional lymph nodes
- A general skin examination
- If many moles or atypical moles, mole mapping is advised
Are all melanomas fatal?
Melanoma in situ is cured by excision as it has no potential to spread.
The risk of spread depends mainly on the Breslow thickness of the melanoma at the time it was surgically removed.
- Metastases risk for melanomas < 0.75 mm : rare
- Metasteses risk for tumours 0.75–1 mm: 5%
- Metastases risk melanomas > 4 mm: 40%.