melanomas
Melanoma is a type of cancer that spreads to other parts of the body. It arises from cells called melanocytes in a pigmented area (eg. skin, eyes). The patterns of this cancer spread is labelled- ‘in situ’ which is located within the layer below the skin (epidermis), ‘invasive’ where it spreads to the layer above known as the dermis and ‘metastatic’ if it spreads to other tissues from the skin. Causes of melanomas include exposure to ultraviolet light and chances of getting melanomas increase with factors such as pale skin, history of skin cancer and the number of moles.
Epidemiology
Melanoma is the fifth most common cancer in the UK, causing 4% of all new cancer cases and being responsible for more cancer deaths than all other skin cancers combined [1]
In 2022, approximately 99,780 new cases of melanoma are estimated to occur in the US
Lifetime risk for white patients is 2.5%, while 0.1 and 0.5% for Black and Hispanic patients respectively [2]
In 2020, an estimated 325,000 new cases of melanoma were diagnosed globally and 57,000 people dies from the disease
Melanoma occurs more frequently in men than in women
The highest incidence rates of melanoma were found in Australia and New Zealand whilst in Africa and Asia, the incidence rates are commonly below 1 per 100,000 [3]
Source: DermNetNZ.org
Melanoma
Superficial (located on the skin) spreading malignant (harmful, growing) melanoma with irregular borders, and different pigmentation
Appears on darker skin with irregular borders and black discolouring on the lesion
Pathophysiology [4]
Medical Student
See non-melanoma cancer pathophysiology for expanded description on the role of UV radiation, genetic mutations and inflammation in the development of skin cancer.
Melanomas may develop in or near a previously existing precursor lesion or in healthy-appearing skin.
A malignant melanoma developing in healthy skin is said to arise without evidence of a precursor lesion.
Melanoma also may occur in unexposed areas of the skin, including the palms, soles, and perineum.
Melanomas have 2 growth phases, radial and vertical.
During the radial growth phase, malignant cells grow in a radial fashion in the epidermis.
With time, most melanomas progress to the vertical growth phase, in which the malignant cells invade the dermis and develop the ability to metastasise.
Patients
See non-melanoma cancer pathophysiology for expanded description on the role of UV radiation, genetic mutations and inflammation in the development of skin cancer.
Melanomas may develop in or near an existing lesion that exists before the development of the disease (precursor lesion) or in healthy-appearing skin.
A malignant melanoma developing in healthy skin is said to arise without evidence of a precursor lesion.
Melanoma also may occur in unexposed areas of the skin, including the palms, soles, and perineum(patch of skin between the genitals and anus)
Melanomas have 2 growth phases, radial (growing wider) and vertical (growing deeper)
During the radial growth phase, malignant cells grow in a radial fashion in the outer layer of the skin.
With time, most melanomas progress to vertical growth, in which the malignant cells invade the dermis (inner layers of the skin) and develop the ability to grow and infect another part of the body.
Multiple dark and light colours seen on the lesion with an asymmetrical shape and irregular borders
Involvement of the fingernail causing discolouration in a linear pattern of the nail plate
Causes [2]
Overexposure to ultraviolet light from;
Artificial tanning beds
Sunlamps
The Sun
Risk factors
History of non-melanoma/ skin cancer
Pale skin
Large number of moles/frecles
Suppressed immune system caused by medication
Weakened immune system with co-existing medical conditions [5]
Older age
Blue eyes or blonde/red hair
Exposure to certain chemicals
History of skin cancer diagnosis [6]
Outdoor exposure through occupation [1]
Source: DermNetNZ.org
Melanoma
Irregular edge with variable discolouration, asymmetry and areas of regression on the heel
Source: Claudio Caridi, Adobe Stock
Melanoma
Black/brown raised lesion with well defined borders
Presentations [2]
Can be categorised into 4 main subtypes of melanoma
Superficial spreading
Accounts for 70% of melanoma
Often found on women’s legs and men’s torsos
Irregular border
Raised
Tan/brown discolouration
Red/white/black/blue spots found within
Nodular melanoma
Accounts for 15-30% of melanoma
Can occur anywhere in the body
Dark lesions
Plaque that is pealy/grey/black in colour
Raised lesions
May look like a tumour from the vessels in the body
Small
Lentigo maligna melanoma
Accounts for 5% of melanomas
Can be found more often with older patients
Found on areas with high amounts of sun exposure (eg. face, hands)
Flat lesion
Tan/brown in colour
Irregular borders
Dark brown/black spots irregularly located on the surface
Named this category after the cancer enters the dermis (layer of the skin)
Acral-lentiginous melanoma
Accounts for 2-10% of melanomas
Most commonly present in patients with darker skin
Found on the palmar (eg. palms) plantar (eg. soles) and subungual (under the nails) skin
Dark areas
Hutchinson’s sign (dark line extending from the nail fold to the top of the nail)
Investigations [1]
Clinical assessment dependent on the type of melanoma and site of impact (use of categorisation)
Medical history of the lesion (shape, size, colour, bleeding etc), associated symptoms, family or personal history and risk factors of melanomas
Examination of the site in clear, bright setting with/ without magnification
Ugly Duckling Sign- the lesions with suspected cancer are different to the current moles
Use of a dermatoscope to examine the lesions and determine whether it is malignant (growing/harmful) or benign (harmless)- this will be done in primary care (eg. GP clinic)
Palapate the lymph nodes (areas of the body that hold lymph and filter foreign substances) to check for melanoma in the regional areas of drainage/filtration
Utilised a 7 point checklist to investigate the area of concern, this includes;
Assigning 2 points for each feature;
Change in colour
Change/or irregular shape
Irregular colour
1 point is assigned to these features;
Largest diameter (distance from one point of the lesion to the opposite point on the widest surface) being 7mm or more
Inflammation
Oozing of the lesion
Change in feeling (eg. itching, burning, pain)
NICE guidelines state that if a lesion is suspected to be melanoma- a biopsy is not recommended but a referral to a suspected cancer pathway (aiming for an appointment within 2 weeks) is necessary.
Differential diagnosis [7]
Apical nevus (unusual looking mole)
Seborrheic keratosis- stuck on lesions that are found on the skin and appear on the chest and back
Pigmented basal cell carcinoma- type of non-melanoma
Squamous cell carcinoma- type of non-melanoma
Spitz (dome shaped, dark mole)/compound (mix of different mole types)/congenital (found at birth)/blue/halo (tan/brown area of impact with a rim of depigmented patch) nevus (mole)
Lentigo simplex- macule (spot) located anywhere on the body
Solar lentigo- macule found on lighter skinned people due to UV radiation exposure
Hemangioma- cherry appearance tumour due excessive blood vessels
Dermatofibroma- tan/brown spot with a dimple within
Paget disease- red, scaly rash on the skin
Pigmented actinic keratosis- type of non-melanoma with increased darkness in colour
Management [2]
Medical students
Treatment of melanoma is primarily by surgical excision (wide local excision).
Recommended tumor-free margin is 1 cm for lesions < 0.8 mm thick, thicker lesions may require larger margins.
Lentigo maligna melanoma are treated with wide local excision and skin grafting.
Melanoma in situ is ideally treated with surgical excision, staged excisions, or Mohs micrographic surgery.
Spreading or nodular melanomas are treated with wide local excision, lymph node dissection if nodes are involved.
Metastatic Melanoma Treatment:
Immunotherapy (antibodies like pembrolizumab, nivolumab, and ipilimumab) lengthens survival.
Combination of antibody inhibitors (nivolumab/ipilimumab) are preferred.
Molecular targeted therapy slows tumour cell proliferation.
Radiation therapy used in specific cases, but the response is poor in some cases
Patients
Treatment of melanoma is primarily by surgical excision- wide local excision (surgical removal of an entire affected region with a wide margin of clear skin)
Recommended tumour-free margin is 1 cm for lesions < 0.8 mm thick, thicker lesions (damaged areas) may require larger margins.
Lentigo maligna melanoma (an early form of melanoma) are treated with wide local excision and skin grafting (procedure when one part of the skin is transplanted to another)
Melanoma in situ (found on the top layer of the skin) is ideally treated with:
Surgical excision- removing tissue with a scalpel
Staged excisions- removal that allows for examination of the entire border of skin affected by skin cancer
Mohs micrographic surgery- aims to remove all the skin cancer by removing affected layers of the skin, examining it under a microscope and repeating that until all of the cancer has been removed.
Spreading or nodular melanomas are treated with wide local excision, lymph node dissection (removing the lymoh nodes) if they are involved.
Metastatic (grown and affects another part of the body) Melanoma Treatment:
Immunotherapy (antibodies like pembrolizumab, nivolumab, and ipilimumab) lengthens survival.
Combination of antibody inhibitors (nivolumab/ipilimumab) are preferred, both used to train the immune system to respond more effectively to cancer and destroy the cancer cells.
Molecular targeted therapy (targets specific molecules responsible for cell growth and replication) slows tumour cell production
Radiation therapy used in specific cases, but the response is poor in some cases
Complications [8]
Scarring after treatment
Hyper/ hypo-pigmentation at sites of treatment
Tightness and skin texture change due to radiation therapy
Lymphedema- sweling of the lymphatic system, leads to fluid buildup
Wound infection after surgery
Hematoma- bleeding under the surface of the skin
Numbness and pain of the sites of treatment
Damage to the muscles/nerves/bones due to untreated cancer
Metastasis- cancer can return and develop to another part od the body
Mental health (anxiety and depression) caused by diagnosis and potentially due to treatment
Myths behind melanoma cancers [9]
Darker skinned people don’t get skin cancer
Only sun exposure can cause skin cancer
Only older people get skin cancer
High SPF sunscreen completely protects you from skin cancer
Tanning beds don’t pose as a risk for skin cancer
You don’t need to wear sunscreen in winter or cloudy days
Questions you may want to ask your doctor
What is the process of investigating skin patches/areas of concern?
Will removing the skin cancer be effective as a single form of treatment?
How do I determine the stage of cancer?
What can I do to prevent the skin cancer spreading?
How can I manage any complications of my skin cancer?
What follow-up support can I get during and after treatment?
Support
Macmillan Cancer Support
NHS Inform
Bibliography
[1] https://cks.nice.org.uk/topics/melanoma/references/
[3] https://www.iarc.who.int/wp-content/uploads/2022/03/pr311_E.pdf
[5] https://www.nhs.uk/conditions/non-melanoma-skin-cancer/
[7] https://www.visualdx.com/visualdx/diagnosis/melanoma?diagnosisId=51936&moduleId=101
[8] https://www.everydayhealth.com/skin-cancer/complications/
