Skin Flashcards
- What types of fibres are found in the layer underneath the epidermis?
Collagen
Elastic fibres
- What layers make up the epidermis?
Basal membrane – stem cells that differentiate into keratinocytes as they move up the epidermis
Stratum spinosum – spines (desmosomes) that connect keratinocytes
Stratum granulosum – cells die and lose nuclei- keratin shells remain and from water tight barrier
Stratum corneum
- How is palmar-plantar skin different from skin in other parts of the body?
There are no sebaceous glands
There is a very thick corneal layer
- Describe the effects of ageing on the skin.
Skin becomes fragile with very little epidermis
Collagen and elastic fibres are of poor quality
- List some different types of inflammatory reactions patterns in the skin.
Vesiculobullous – forms bullae Spongiotic – becomes oedematous Psoriasiform – becomes thickened Lichenoid – forms a sheeny plaque (in the dermis) Vasculitic – associated with vasculitis Granulomatous – associated with granulomas
- What is bullous pemphigoid? Describe the macroscopic appearance.
Occurs in elderly patients on their flexor surfaces
Characterised by the formation of tense bullae
Autoimmune disorder driven by IgG and C3 which attack the basement membrane
They recruit eosinophils which release elastase which further damages anchoring proteins (anchoring lower keratinocytes to the basement membrane)
- How can bullous pemphigoid be definitively diagnosed?
Immunofluorescence will show IgG and C3 along the dermo-epidermal junction
- Describe the macroscopic appearance of pemphigus vulgaris.
Blisters are flaccid meaning that they rupture easily exposing a red raw surface underneath. Blisters are intra epidermal then epidermis sloughs off
- Outline the pathophysiology of pemphigus vulgaris.
IgG-mediated disease where the damage is occurring within the keratinocyte layers
- What is acantholysis?
Loss of intercellular connections leading to loss of cohesion between keratinocytes
- Describe the macroscopic appearance of pemphigus foliaceus.
You rarely see intact bullae because they are so thin and fragile
You are likely to see some flaky remnants of old bullae
IgG-mediated attack on the outer layer of keratinocytes (where the stratum corneum is found)
- What is hyperparakeratosis?
Thickening of the skin on the surface where the patient has been scratching
The epidermis gets thicker
- What are the main immune mediators in eczema?
T-cell mediated
Eosinophils are also recruited
NOTE: this pattern is also seen in drug reactions
- How is the keratinocyte turnover time different in psoriasis compared to normal skin?
Normal skin turnover = 50 days (time for a keratinocyte to go from the bottom of the epidermis to the top)
Psoriasis = 7 days
This leads to thickening of the epidermis and you get a layer of parakeratosis at the top
- Which layer of the epidermis disappears in plaque psoriasis and why?
Stratum granulosum – there is not enough time to form it
- What can neutrophil recruitment to the epidermis in plaque psoriasis cause?
Formation of Munro’s microabscesses
- What is lichen planus and what are its main features?
Lichenoid reaction pattern
T-cell mediated
Presents with papules and plaques that are slightly purplish in colour on the wrists and arms
In the mouth it presents as white lines (Wickham striae)
- Describe the histological appearance of lichen planus.
Distinction between dermis and epidermis is difficult to see due to lymphocyte-mediated destruction of the bottom layer of keratinocytes
There is band-like lymphocytic infiltration just under the epidermis
NOTE: this is also seen in mycosis fungoides
Give an example of a vasculitic skin reaction
pyoderma gangrenosum
- Which histological feature is classic of seborrhoeic keratosis?
Horn cysts – entrapped keratin surrounded by proliferating epidermis
NOTE: the epidermis is proliferating in an orderly manner
- Describe the appearance of a sebaceous/epidermal cyst.
Smooth surface Non-mobile Tend to have a punctum Can get infected/rupture Can smell really bad
- Describe the macroscopic appearance of a basal cell carcinoma.
Rolled, pearly edge with a central ulcer and telangiectasia
- Describe the histological appearance of a basal cell carcinoma.
Cancer arises from the keratinocytes along the bottom of the epidermis (basal cells)
They can infiltrate through the basement membrane
They are locally infiltrative but don’t metastasise
- What is Bowen’s disease?
Squamous cell carcinoma in situ
- Describe the histological appearance of a benign junctional naevus.
Melanocytes expand in their normal position sitting on the basal layer and form nests
They are circumscribed and uniformly pigmented
- Describe the normal migration of melanocytes as they mature.
As they mature they become smaller and go deeper
- What are some clinical signs suggestive of a malignant melanoma?
Asymmetry Border irregularity Colours Diameter Evolution
- Describe the histological appearance of malignant melanoma.
Melanocytes start migrating upwards through the epidermis (pagetoid spread)
They become active and lose the ability to differentiate
Melanoma thickness > 4 mm has a > 50% mortality
