Pigmented Lesions Flashcards
What percentage of the cells in the basal layer are melanocytes?
5-10%
Describe how melanocytes form
- Epidermal melanocytes originate in the neural crest
- As a foetus, the melanocyte migrates from the neural crest to the dermo-epidermal junction.
- They reside as a single cells in the basal layer.
How is skin colour controlled?
Dark skinned individuals do not have more melanocytes.
They have more melanosomes.
Melanosomes are secreted by melanocytes into surrounding keratinocytes.
At what stage of life do the number of moles sharply increase?
Puberty
What is a junctional melanocytic naevus?
A mole that is confined to the dermoepidermal junction
Over time, naevus cells can extend into the dermis.
What is this called?
A compound naevus
Over more time, melanocytic cells can migrate fully into the dermis.
What is this called?
Intradermal naevus.
(All the junctional components have been lost)
What is this?
An intradermal naevus
- No pigment
- Papillomatousnodules.
Is this a Junctional Naevus or a Compound Naevus?
Compound Naevus
- Usually raised.
- Colours vary
- Sometimes hyperkeratotic
What is a CMN?
Congenital Melanocytic naevi
(Think Birthmark)
How are congenital naevi classified?
(According to size)
- small CMN = <1.5 cm diameter
- medium CMN = 1.5 - 19.9 cm diameter
- large or giant CMN = 20 cm or more in diameter
Why do Giant Congenital Melanocytic Naevi need to be monitored?
They have a 30% chance of malignancy
What are the other benign naevi to be aware of apart from CMN?
- Spitz naevus
- Halo naevus
- Becker’s naevus
- Blue Naevus
What is this?
When & Where does it occur?
How do you treat it?
Spitz Naevus
- It usually grows rapidly on the face of a child
- Reaches 1-2 cm and then stops.
- AKA Juvenile Melanoma - but is benign
- Best to excise as it is difficultto differentiate from a melanoma
What is this?
Halo Naevi
- Occurs on the trunk of children or adolescents
- The body’s immune system is destroying the naevus cells.
What is this?
Becker’s naevus
- Becomes darker and hairy after puberty
- More common in adolescent males
- No effective treatment
What benign naevus is this?
A Blue Naevus
- Deep dermal collection of melanocytes.
- As they migrate from the neural crest to the epidermis during foetal life they stop in the dermis rather than the dermalepidermal junction
- Usually occur on the scalp, face, hands and feet.
What are the characteristics of an atypical mole?
- >5mm
- Irregular shape
- Smudged border
- Irregular pigmentation +/- erythema
- Papular + Macular component.
What % of the population have Atypical Mole Syndrome?
What is their risk of developing melanoma?
1-5% of the population
10x risk of melanoma
What is FAMM syndrome?
Familial Atypical Multiple Mole-Melanoma Syndrome
- Mutation in the CDKN2A or CDK4 gene
- Associated with pancreatic cancer.
- 400x increase in melanoma risk if 1st and 2nd degree relatives have atpyical naevi + melanomas.
What % of melanomas arise melanocytic naevi?
30%
What factors lead to an increased risk of melanoma?
- Sun exposure
- Skin type
- Large numbers ofmelanocytic naevi
- Large CNS
- Family history
- Personal history
- Immunosuppresion.
Describe the cellular pathway whereby melanomas form?
40-60% of melanomas result from a BRAF mutation.
This leads to MEK & ERK phosphorylationand cell proliferation.
This is independent of extracellular growth factors.
Describe the ABCDE Rule
- Asymmetry
- Border irregularity
- Colour irregular/variable pigmentation
- Diameter >6 mm (not always helpful)
- Elevation / Enlargement / Evolution– any mole which clearly changes over weeks to months
What is this?
Superficial spreading malignant melanoma
- Most common melanoma
- 80% of primary melanomas
- Excellent prognosis (They are usually <1mm thick)
What type of melanoma is this?
Nodular Melanoma
- 10% of all melanomas
- Worse prognosis due to vertical growth face from the beginning.
- More common in males
- More common on the trunk
- Differential includes a vascular lesion.
What type of melanoma is this?
Lentigo Maligna Melanoma
- 10% of cases
- Large irregular freckle
- Solar lentigo is benign but lentigo maligna is cancer in situ.
- Lentigo maligna melanoma can grow out of a lentigo maligna - invasive nodule develops with vertical growth phase.
What is the most common form of melanoma in dark skin types?
Acral Melanoma
What is Hutchinson’s Sign?
It is pigmentation that involves the nail bed.
A positive sign of acral melanoma.
What type of melanoma is this?
Amelanotic melanoma
What is the most important prognostic factor melanomas?
Tumour thickness (aka Depth)
Breslow Thickness
Describe the Breslow Thicknes Stages
Describe the Breslow thickness survival rates
What Wide Local Excision Margins are recommended by the British Association of Dermatologists?
In situ: 5 mm
<1 mm: 1 cm
1.1 - 2 mm: 1-2 cm*
2.1 - 4 mm: 2-3 cm*
>4 mm: 3 cm
* Depends on anatomical site
When should the sentinel lymph node be biopsied in melanoma?
If the thickness is greater than or equal to 1mm
Is Sentinel Lymph Node Biopsy diagnostic or therapeutic?
Diagnostic
It is primarily a staging procedure - however, patients will go on to have a complete lymph node dissection.
How are unresectable or metastatic melanomas managed?
-
BRAF inhibitors -Vemurafenib and Debrefenib
- Only used in patients who have the V600E mutation.
- MEK inhibitors - Trametinib
-
Immunotherapy
- CTLA-4 Inhibitors - Ipilimumab
- PD-1 Inhibitors -Pembrolizumab orNivolumab
How should patients with stage 1A Melanoma be followed up?
3-4 monthly for 1 year and then discharged.
How should patients with melanoma in situ be followed up?
No Follow Up Needed
How should patients with Stage 1B to IIIA be followed up?
3-4 monthly for the first 3 years
then
Twice yearly for another 2 years
How should patients with Stage IIIB and Above melanoma be followed up?
Every 3-4 months for the first 3 years
then
Twice yearly to 5 years
then
Annually to 10 years.
What is the role of PET-CT scans?
Offered to patients suffering from Stage IIC and above
Offer at baseline
then
6 monthly for 3 years
then
Annually for 5 years.
What blood test should be checked with melanoma patients?
Vitamin D
(Patients are advised to avoid the sun)
What are some features of melanoma on dermatoscopy?
- Asymmetry of pigment network
- Asymmetry of lesion
- Blue- white veil
- Black dots and globules
- Pseudopods
- Asymmetrical vessels
- Areas of regression
How should suspicious solar lentigo be biopsied?
(Suspecting lentigo maligna)
Take an ellipse excision from the most abnormal looking section
