Skin Cancer Flashcards
(45 cards)
1
Q
What are Merkel cells ?
A
- specialist cells found in digits,lips, oral cavity & hair follicles
- stimulated when keratinocytes are deformed to secrete chemicals that generate an action potential in local neurons
2
Q
Describe the epidermis
A
- superficial layer of the skin
- made of epithelial cells
- has no vascular system
-contains specialised epithelial cells which are organised in a stratified structure
3
Q
Describe the stratified structure of the epidermis
A
- cornified cell layer
- granular layer
- squamous epithelial tissue
- basal layer
- basement membrane
4
Q
Describe the Cornified Cell layer of the epidermis
A
- stratum corneum
- keratinocytes terminal differentiate to corneocytes and provide a barrier to the external environment
- stops excessive water loss
5
Q
Describe Corneocytes
A
- filled with keratin
- no nucleus
- keratinised layer stops water loss from inside & stops penetration of water from outside
6
Q
Describe the granular cell layer of the epidermis
A
- 1-3 cells thick
- stratum granulosum
- keratinocytes in this layer contain lots of keratohyline granules in cytoplasm –> key players in keratinisation
- eventual terminal differentiation removes organelles from cells
7
Q
Describe the squamous cell layer
A
- stratum spinosum
- 5-10 cells thick
- keratinocytes take on a flattened shape - appear squamous and become flatter as they travel to the top layer
- contain lamellar granules which contain hydrolytic enzymes
- keratin fibres formed around the nuclei
8
Q
Describe the basal cell layer of the epidermis
A
- stratum basale
- where keratinocytes begin their journey & proliferate
- keratinocytes appear column shaped & attached to basement membrane
- long elongated uncle & support squamous cells
9
Q
What are Melanocytes
A
- pigment synthesising cells
- found in the epidermis, iris & hair
- responsible for melanin production & its transportation to keratinocytes via melanosome
- 1 melanocyte communicates with 30/40 keratinocytes in an epidermal melanin unit
10
Q
Describe Langerhans cells
A
- immune cells involved in T cell responses
- found in all layers of the epidermis - most abundant in the squamous cell layer
- during infection Langerhans cells act as 1st responders to pathogens
11
Q
Describe the Dermis
A
- contains extracellular matrix & collagen
- fibroblasts produce collagen & other proteins which give skin its flexibility & structure
- thickest layer
- contains fibrous, filamentous & amorphous connective tissue
- made of 2 layers = papillary & reticular layers
12
Q
Describe the Papillary Dermis
A
- uppermost layer of the dermis
- joined to the basal membrane of the epidermis
- contains loosely arranged collagen fibres
- papillae (finger-like projections) that extend towards the epidermis contain capillaries & Meissners Corpuslcles
13
Q
Describe the reticular dermis
A
- lower layer of dermis
- consists of dense connective tissue - densely packed collagen & elastic fibres
- contains roots of hair, sebaceous glands & sweat glands
14
Q
Describe Dermal Fibroblasts
A
- most abundant cell in the dermis
- responsible for the production of key matrix proteins - fibrillin, elastin & collagen
- quantity & quality declines in ageing skin
15
Q
Describe Basal Cell Carcinoma
A
- 80% of skin cancers
- basal epithelial cells affected at base of epidermis
- mostly found on sun exposed skin
- rarely metastasize
- often needs surgical removal
16
Q
How can BCC manifest?
A
- open sore that won’t heal
- red patch
- shiny skin coloured bump
- area that looks like a scar
- pink/brown growth
17
Q
What does PIPS stand for ?
A
P53 Immunopositive Patches
18
Q
Describe PIPS
A
- areas of skin that are immunopositive for P53
- usually found in sun-exposed areas
- thought to be precancerous areas
19
Q
Describe Squamous cell carcinoma
A
- 2nd most frequent type of
- involves squamous layer
- likely to be found on sun-exposed areas
- more invasive than BCC but unlikely to metastasize
20
Q
How can SCC manifest?
A
- persistent patch on skin that is scaly
-has irregular borders - becomes crusty
- occasionally bleeds
21
Q
Describe the molecular mechanisms of cutaneous squamous cell carcinoma (cSCC)
A
- often a continuation/development of actinic keratinosis (AK)
- Some AKs acquire genetic and epigenetic changes and progress to cutaneous squamous cell
carcinoma in situ (SCCIS) and eventually cSCC - A small number of cSCC can gain additional genetic and epigenetic features that lead to
metastatic disease
22
Q
What are some examples of exogenous mutagens ?
A
- sunlight (UVA & UVB)
- smoking
- diet
23
Q
What are some examples of endogenous mutagens ?
A
- free radical damage due to reactive oxygen species
24
Q
Describe Melanoma
A
- effects melanocytes
- more aggressive than BCC & SCC
- can effect body parts not exposed to the sun
- can metastasize to brain,liver & lungs
25
What are the 4 major forms of melanoma ?
- superficial spreading
- nodular
- lentigo maligna
- acral lentiginous melanomas
26
How can melanoma be staged?
- The Clark Scale
- The Breslow scale
- TNM Staging
27
Describe the Clark Scale
- examines the depth of the legion by observing tumour in various skin layers
- histological analysis is important
28
Describe the Breslow Scale
- evaluates how thick the melanoma is
29
Describe TNM Staging
- based on thickness of lesion & evaluation of its spread to lymph nodes & secondary sites
- number staging system (0-4)
0= tumour is limited
4= metastasis to lymph nodes
30
Describe Melanocytic nevi
- nevi = birthmarks
- can congenital or appear late life
- atypical/excessive amounts of nevi acquired later in life are a potential risk factor
31
Describe Merkel Cell carcinoma
- rare but aggressive
- more common is sun exposed areas, but can be in other places
- can metasize to brain/bone/liver/lungs
- 2nd most common cause of skin cancer deaths
32
What are some risk factors for Merkel Cell Carcinoma ?
- over 50 y.o
- male
- white
- HIV Positive
- weakned immune system
33
What are the molecular mechanisms of Merkel cell carcinoma ?
- viral form = Clonal integration of Merkel cell polyomavirus DNA into the tumor genome
with persistent expression of viral T antigens causes at least 60% of all MCC
- UV damage
34
What is an example of a rare skin cancer?
Kaposi's sarcoma
35
Describe Kaposi's Sarcoma
- formed in cells that line blood& lymph vessels
- type 1 = men over 50, caucasian/middle eastern backgrounds - slow to gorw & treatable
- type 2= aggressive & associated with immunocompromised (HIV) - presents as red/purple/brown lesions
36
Describe the molecular mechanisms of Kaposi's sarcoma
* oncogenic virus named Human Herpes Virus 8.
* The viral infection in itself, along with the oncogenic properties of
HHV8 and with immune system dysfunction, forms the grounds on
which Kaposi’s Sarcoma may develop
37
Describe Dermatofibrosarcoma protuberans
* Cancer arises from cells found in dermis
* Presents like a cyst, scar, or bruise
* Most likely to form on arms legs or torso – but can be found anywhere
* Treatments include Mohs surgery, where tissue is removed in layers and assessed histologically until no cancerous tissue is found ->radiation therapy and then drug therapy such as imatinib
38
Describe the Molecular mechanism of
Dermatofibrosarcoma protuberans
molecular pathogenesis of dermatofibrosarcoma protuberans (DFSP) involves distinctive rearrangement
of chromosomes 17 and 22 leading to formation of the COL1A1-PDGFB fusion gene
39
Describe Sebaceous carcinoma
Starts in a sebaceous gland in the dermis
* Usually, a painless lump or a thickening of skin near the eye
* 75% are periocular or near the eye
* 25% are extraocular (not near the eye)
* Can look benign on first inspection – so diagnosis is difficult
* Therapies include Mohs surgery, radiation therapy
for later stages
40
What does prognosis of SCC depend on?
* Stage
* Immunosuppression
* Smoker/use of tobacco
* general health
41
What does treatment of BCC & SCC depend on?
* Type
* Stage of the cancer, for squamous cell carcinoma.
* Size and anatomical location of the tumour
* general health
42
Breifly describe Mohs Surgery
- At each step the piece of tissue removed is observed under microscope to check for cancerous cells.
- The aim is to take as little tissue as possible – while still taking enough.
43
What drugs are used in melanoma chemo ?
- Alkylating agents
- taxanes
- platinum agents
44
What are some common chemo side effects ?
- myelosuppression
- nausea
- pain
- anaemia
45
Describe Photodynamic Therapy
Photodynamic therapy(PDT) uses a
combination of a photosensitiser and lightto kill cells. Usually used for;
* BCC
* In situ SCC
* AK
