Melanoma.
There’s no such thing as simply ‘a melanoma’.
Red Alert
Let’s repeat that Nodular melanoma is dangerous. Look out for a rapidly growing red or brown nodule.
Melanoma in the skin cancer clinic
Melanoma diagnosed at a routine skin check is a very rewarding outcome because early treatment will result in cure. Every effort should be made for an early diagnosis of malignant melanoma.
Who gets them?
Melanoma is most common in adults with fair skin and significant UV exposure. Whilst melanoma is most common with increasing age, melanoma also occurs in older children and young adults.
What does Melanoma look like?
Superficial spreading melanoma
The most common and best known type of melanoma is superficial spreading melanoma (SSM) where The tumor cells spread horizontally in the upper layers of the skin. This type of melanoma accounts for 55-60% of melanoma, and is the type most often occurring in younger people. SSM is most common on the back in men, and on the leg in women. SSM can grow over months or years, particularly in the horizontal growth phase. The melanoma appears fairly flat and is usually pigmented.
Amelanotic Melanoma
Amelanotic means ‘no melanin’ and this type of melanoma appears to have no pigment, whilst hypomelanotic melanoma is partially pigmented.
Nodular Melanoma
As the name suggests, nodular melanoma is elevated and tend to be aggressive. Any ‘elevated, firm, growing’ lesion (EFG) needs to be taken seriously. Around half of nodular melanomas appear to have little or no pigment – they’re just pink or skin coloured growths – although around 90% of nodular melanoma seen through a dermatoscope does have at some pigment.
The rule of thumb for nodular melanoma is to get any growng pink lesion that has not gone within a month checked out urgently
Lentigo Maligna
Lentigo Maligna is commonly found on sun exposed areas of the head and neck. This type of melanoma may be hard to spot on typically sun damaged skin because the melanoma tends to blend into the background look like a dirty-brown patch. Lentigo maligna affects only the upper layer of skin (epidermis) and may grow for many years before growing down into the dermis when it is called lentigo maligna melanoma.
Acral Melanoma
Acral Melanoma accounts for around 1-2% of melanoma in Australia. This type of melanoma is not related to sun exposure, and occurs on the sole of the feet, palms of the hands, or nail-bed. This is the reason why a full skin check does involve a look at the soles of the feet. Darker skin such as people of Asian or African descent are at greater risk.
Desmoplastic melanoma.
This type of melanoma is rare and easily missed – it tends to be felt as a firm lesion on the head or neck in older people, and may arise from lentigo maligna.
Dermoscopic Findings
Irregular network
Regression Structures
Radial Streaming
Pseudopods
Atypical dots or globules
Dots and clods
Periperal globules
Peripheral lines
Peripheral Globules
Blue white veil
Negative pigment network
Regression
White Lines
Polymorphous vessels
Irregular vessels
Why do they matter?
Why is Melanoma so important?
- Australia has the second-highest rate of melanoma in the world.
- The overall rate of melanoma in Australia is still increasing, and has almost doubled in the last 34 years.
- Melanoma is the 4th most common cancer in Australia (other than the non melanoma skin cancers).
- Most melanoma is caught at the curable stage.
- Melanoma can easily be mistaken for benign skin lesions.
Who is at risk of melanoma?
The strongest risk factors are:
- Family history (first degree relatiaive ie. a brother, sister, mother, father or child with melanoma)
- Lots of moles (eg. More than 100)
- Large unusual-looking moles – atypical moles.
- Previous melanoma
Other risk factors are:
- Red hair, blue eyes, skin that easily burns
- History of blistering sunburn. Specifically, a history of 5 or more episodes of blistering sunburn doubles the risk of melanoma.
- Previous use of sunbeds – particularly at an early age.
- Being on immunosuppressant medication.
The gap between rates of melanoma in younger and older people is increasing. Nevertheless, younger people still get melanoma, with a rate of 9.4 cases per 100,000 reported in 2016.
Melanoma is overall more common in men than women. However, Melanoma is more common in women than men under the age of 40, reflecting hormonal factors and different patterns of UV radiation.
UV exposure, age and genetics lead to genetic aberrations such as a single substitution of V600F of the BRAF gene that accounts for 50% of melanoma.
Can I tell if I have a melanoma?
You simply can’t DIY whether a mole is harmless or not. Why? Because expert use of a dermatoscope is required to truly tell whether a mole is definitely harmless.
Around 65% of melanoma develope de novo whilst 35% develop from a pre-existing mole. In other words, you need to keep an eye out for both changing lesions as well as new lesions! This doesn’t help much, right?
Should you worry about every new lesion? Harmless moles continue to appear in Young to middle aged adults whilst adults from their 30’s will will skin lesions like seborrhoeic keratosis and age spots (solar lentigo). Yet early melanoma can look like either of these lesions.
How can you evaluate change in a lesion? The famous ABCDE is a good starting point. A changing lesion is one that has a change in any of the Assymetry, Border, Colour, Diameter or is Evolving. In truth, any change is important. Melanoma may not be pigmented. Indeed, melanoma may be entirely pink. The EFG rule was added later to help identify a dangerous type of melanoma called nodular melanoma.
A self skin check is certaintly better than no skin check but the skin cancer doctor will greatly refine the probability of melanoma with dermoscopy at a skin check.
Dermatoscopy examination has two benefits
- A skin lesion that looks fine with the “naked eye” may be concerning after dermoscopy.
- A skin lesion that might otherwise look “nasty” may be entirely reassuring after dermoscopy.
Biopsy & Treatment
The Biopsy
The initial excision is for diagnosis and staging, not for treatment.
The pathology report will indicate how dangerous the melanoma is. The single most important information is the ‘Breslow thickness.’ Under 1mm is ‘good’ whilst >4mm is ‘bad.’
A melanoma will need re-excising after the initial biopsy.
It should be emphasized that the initial excision is for diagnostic purposes – even though the whole lesion will probably have been removed. A melanoma will require a second ‘definitive’ surgical procedure.
Staging
- Melanoma staging was last updated by The American Joint Committee on cancer (AJCC). Melanoma cancer classification is indicated by the initials TNM:
- T for tumour
- N for lymph nodes
- M for Metastases
Most melanoma is diagnosed at the curable stage. Let’s assume there is no lymph node involvement (N0) and no metastases (M0), and let’s assume the breslow thickness is <1mm. The tumour stage depends on breslow thickness and the presence or absence of ulceration, giving the possibilities:
- Tis Melanoma in situ
- T1a <0.8mm thick without ulceration
- T1b <0.8 with ulceration, or 0.8 to 1mm without ulceration
- T2a >1 to 2mm without ulceration
- T2b >1 to 2mm with ulceration
Once you know The TNM classification you can work out the staging.
- T1a is stage IA with a 95% 10 year survival.
- T1b or T2a is stage 1B with an 86% 10 year survival.
Surgical treatment
The diagnosis may come as a shock because melanoma has such a bad reputation. However, melanoma diagnosed these days is usually curable.
Treatment will require further skin surgery in the form of a ‘wide local excision’ (WLE). Tumor cells after spready beyond the margins that are visible clinically. Excision margins vary from 5mm to 2cm depending on the staging.
1cm margins are recommended for melanoma <1mm thick in Australian guidelines updated in 2018, whilst 5mm margins are the usual recommendation for melanoma in situ.
Local Recurrence of Melanoma
Most melanoma diagnosed nowadays in Australia has an excellent prognosis.
A “local recurrence” can be implied by a melanoma that subsequently appears close to the original one. In other words, a new skin lesion near a scar from an excised melanoma might be a local recurrence.
There are two types of local recurrence:
- A true local recurrence where the original melanoma has grown immediately adjacent to the scar tissue. This is rare because original melanoma will have been cleared with generous margins as already described. Also, most local recurrences appear to lesions that are separate from the scar tissue.
- Microscopic lymphatic drainage to local skin
A routine skin check will therefore include close examination of the skin next to the scar from a previously removed melanoma.
New drugs for advanced melanoma
Melanoma that was previously thought untreatable may now be treatable with drugs that targe the immune system. A variety of immunotherapy is now available, targeting a specific aspect of the immune system – Interleukin 2, Interferon-alpha, and checkpoint inhibitors.
Immunotherapy is a major advance on traditional chemotherapy for metastatic melanoma.
Patients in Australia with advanced melaoma will typically be treated at their local ‘melanoma unit’ which is made up of melanoma specialists in the field of pathology, plastic surgery, dermatology, oncology and radiotherapy.
Malenoma Pathology Report
These are some of the key terms that may be used a melanoma pathology report
Atypical Melanocytes
Atypical Melanocytes don’t look normal eg. the nuclei look different.
Pagetoid Spread
The atypical melanocytes spread to the upper layer of the epidermis.
Breslow thickness
The distance between the granular layer of the epidermis and the deepest portion of melanoma.
Mitotic Rate
The rate of mitoses of the melanoma cells (rate of Cell division)
Clark Level
The level of invasion
Lymphocytes
Lymphocytes are types of white blood cell involve in immunity. The melanoma cells may attract attention from the immune system in the form of tumour infiltrating lymphocytes.
Regression
Regression indicates loss of melanoma cells following attack by the immune system.
Neurotropism
Neurotropism indicates a propensity to infiltrate the nerve tissue of the skin.
Lymphovascular Invasion
Lymphovascular Invasion refers to invasion of the lympatic or vascular vessels of the skin by melanoma cells.
South East Skin Clinic
You are welcome to make an appointment at our skin cancer clinic in Cleveland, Brisbane Bayside.
Please Telephone us for any enquiries