Corrections 2 Flashcards
What is the most common cancer globally?
Basal cell carcinoma
What are the 3 layers of the skin?
1) Epidermis
2) Dermis
3) Hypodermis
What are the 5 layers of the epidermis?
- Stratum basale (inner)
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum (outer)
What are the principal cells of the epidermis?
Keratinocytes
Describe the process of keratinsation
The basal cells of the epidermis are undifferentiated, proliferating cells that migrate upwards through all the 5 layers.
It takes about 30 days for the cells to migrate from the basal layer to cross the stratum corneum where they are finally shed.
In which layer of the skin are adipose tissue and sweat glands found?
Hypodermis
What genes are normally affected in BCC? (2)
1) PTCH
2) TP53
What is the most common mechanism of spread of BCC?
Local invasion
What are the 3 types of BCC?
1) Nodular (most common)
2) Superficial
3) Morpheaform
What is the most common type of BCC?
Nodular
What 2 topical creams may be used in the mx of BCC?
1) imiquimod
2) fluorouracil
What layer of the skin does BCC occur in?
In the basal cell layer (the lowest part of the epidermis).
What layer of the skin does SCC occur in?
In the stratum spinosum layer of the epidermis.
Are BCC and SCC both cancers of keratinocytes?
yes - both BCC and SCC develop from keratinocytes in the epidermis
What gene is often involved in SCC?
p53
What is the most common skin cancer in Fitzpatrick skin types V and VI (brown and black skin)?
SCC
What are 2 precancerous skin conditions that are considered pre-cursors to SCC?
1) Bowen’s disease
2) Actinic keratosis
What are 2 biopsy options used in the diagnosis of SCC?
1) Excisional/shave
2) Incisional/punch
When is an incisional/punch biopsy indicated in SCC?
If the SCC is;
a) large
b) in an inaccessible area
c) in a cosmetically sensitive area
When is an excisional/shave biopsy indicated in SCC?
If the SCC is;
a) small
b) in an accessible area
What does an excisional/shave biopsy involve?
Involves the removal of the whole lesion
What does an incisional/punch biopsy involve?
Samples only part (usually 4mm) of the lesion.
1st line mx of Bowen’s disease?
1) cryotherapy
2) topical 5-fluorouracil
Mx of invasive SCC (i.e. growing beyond the epidermis)?
Conventional surgical excision with a minimum of 4mm margins
What surgery is indicated in SCC in a cosmetically sensitive place (e.g. face)?
Mohs micrographic surgery (aka margin-controlled excision)
What diametes defines low risk vs high risk SCC?
SCC with a diameter <20mm –> low risk
SCC with a diameter >20mm –> high risk
How does SCC being low vs high risk impact surgical excision?
Low risk SCC (<20mm) –> 4mm margins
High risk SCC (>20mm) –> 6mm margins
What diameter of SCC gives a poorer prognosis?
> 20mm
What depth of SCC gives a poorer prognosis?
> 4mm
What depth of SCC gives a better prognosis?
<2mm
What are the 4 subtypes of melanoma?
1) superficial spreading
2) nodular
3) acral lentiginous
4) lentigo maligna melanoma
Key features of SCC?
Ulcerating, crusting & bleeding
Which type of melanoma is typically found on the palms, soles or under the nails?
Acral lentiginous melanoma
What genetic condition has a skin cancer predisposition?
Xeroderma pigmentosum
What diameter are most melanomas?
> 6mm