Skin: moles and papules Flashcards
What are the 3 layers of skin?
Epidermis
Dermis
Subcutaneous (hypodermis)
What embryological layer is the epidermis derived from?
Ectoderm
What type of cells are found in the epidermis?
(Keratised) Stratified squamous epithelium
What are the epithelial cells in the epidermis filled with?
What are some of the properties of this substance?
Keratin
A protein that is protective and insoluble.
What lies between the epidermis and the dermis?
Basement membrane
Which layer are hair follicles and sweat glands found in?
Dermis
Name the 2 layers of the dermis
Papillary - finger like projections into the epidermis
Reticular
What 5 things can be found in the dermis and not in the epidermis?
Collagen fibres
Elastin fibres
Blood vessels
Nerves
Lymphatic vessels
Why is the subcutis important in thermoregulation?
It is a rich adipose (fat) layer that acts as a reserve for energy resources
What fibres that can be found in the dermis degenerate with age and cause wrinkles?
Collagen
Elastin
Name the 4 layers of the epidermis from basement membrane upwards
Basal layer
Spinous layer
Granular layer
Cornified layer
Give some characteristics of the basal layer of the epithelium
Single layer of cells
Epidermal stem cells - constantly dividing to form keratinocytes.
Aim of keratinocytes is to form keratin and move up through the epidermis.
Give some characteristics of the spinous layer of the epithelium
Variable thickness - usually 3 cell layers
Contains keratin fibrils
Give some characteristics of the granular layer of the epithelium
Few cell layers thick
Contains granules that stain in histology
Keratin fibrils become fibres
CELLS LOSE NUCLEUS
Cells get coated by glycophospholipids that makes the cells water-proof
Give some characteristics of the cornified layer of the epithelium
Contains keratin
Cells have no nucleus but are waterproof (glycophospholipids)
What is the difference in the epidermis in patients with psoriasis?
The amount of time it takes for cells to move from the basal layer to the cornified layer is reduced
How are cells in the basal layer of the epidermis connected to the basement membrane?
Hemidesmosomes
What changes keratin fibrils into keratin fibres?
Keratohyalin granules
What releases glycophospholipids into the cornified layer of the epithelium?
What does this do to the cells?
Lamellar bodies
Makes the cells water-proof
What causes the dark colour of skin?
What is this formed by?
Which layer of the skin is this found in?
Melanin
Melanocytes
Basal layer of the epidermis
What is formed in the epidermis during histological preparation?
Desmosomes
Where are Merkel cells usually found?
In the basal layer of the epidermis
What do Merkel cells do?
They are in close proximity to the nerve endings and have a sensory function
Name a difference between ‘thick’ and ‘thin’ skin
Thick skin has a thick cornified layer and an additional stratum lucidum
What type of hair is thin and can be found all over the body?
Vellus hair
What type of hair can be found on the skull, beard, pubic and axillary regions. What is it for?
Terminal hair
Protection
What are hair follicles made from?
Keratin
As a hair follicle grows, what does it associate with?
A sebaceous gland
Erector pilli muscles
Where is sebum secreted from?
Sebaceous glands
What 3 things make a pilosebaceous unit?
Hair follicle
Sebaceous gland
Smooth muscle
Which gland is affected in acne?
Sebaceous glands
What is the role of the eccrine sweat glands?
2 parts - secretory and duct
Take up plasma filtrate and filter out electrolytes e.g. NaCl.
Water is filtered out as sweat
Concentration of sweat depends on hydration status of the patient
What is the role of the apocrine glands?
Under hormonal control
Associated with hair in the axilla and groin region
Secretion contains fats and proteins.
Secretion does not smell until it comes into contact with bacteria on the skin’s surface
What is the nail plate formed from?
Keratin
Describe the blood supply to the skin
Veins and arteries form 2 plexi:
A cutaneous (deep) pleuxus between the subcutis and the dermis
and
A superficial plexus between the dermis and the epidermis
The epidermis itself has no blood vessels going through it
If a skin lesion is flat, can be seen but is not palpable, what is it called?
What term would be used to describe a larger area of a flat lesion?
Macule
A patch
If a skin lesion is flat, can be seen but is not palpable, what is it called?
What term would be used to describe a larger area of a flat lesion?
Macule
<5mm
A patch
If a skin lesion is raised and solid, and less than 5mm in size, what is it?
Papule
If a skin lesion is raised and solid, and more than 5mm in size, what is it?
Nodule
Give an example of a malignant papule/nodule (depending on size)
Basal cell carcinoma
If a skin lesion is raised, can be felt, but the area is greater than the height, what is it?
Plaque
Where are plaques normally found?
Give a common example of a plaque
Extensor surfaces e.g. elbow/knee region
Psoriasis
What happens to the keratinocytes in psoriasis?
And the epidermis in general?
They become larger and become nucleated - become porokeratosis
Blood vessels become more superficial
If a skin lesion is raised, filled with clear serous fluid, and <5mm, what is it?
Vescile
If a skin lesion is raised, filled with clear serous fluid, and >5mm, what is it?
Bullae
If a skin lesion is raised and filled with pus, what is it?
Pustule
Which conditions can present with vesicles/bullae?
Herpes zoster
Shingles
Chicken pox
What is a neoplasm?
A lesion resulting from the autonomous growth of cells in the absence of a stimulus
Describe the appearance of a benign neoplasm
Slow expansive growth
Symmetrical
Capsule present
Resembles tissue of origin
Differentiated cells
Smooth surface
Describe the appearance of a malignant neoplasm
Fast, invasive, metastatic growth
Crab-like appearance
No capsule
Does not resemble tissue of origin
Undifferentiated cells
Irregular surface, may ulcerate and haemorrhage
Name the 3 forms of skin cancer
Basal cell carcinoma
Squamous cell carcinoma
Malignant melanoma
What is the key prognostic factor in skin cancer diagnosis?
Depth of invasion
Discuss basal cell carcinoma (BCC)
Commonest form of skin cancer in the UK
Slow growing
Usually does not metastasise but can become locally destructive
Name 3 risk factors for BCC
UV radiation exposure
Immunosupression
Inherited conditions e.g. xeroderma pigmentosum
Describe the appearance of a BCC
Slow growing
Can be superficial or nodular
Rolled edge
Punctum in middle +/- abscess
Associated with blood vessels
Slowly eating away at the skin
Usually located in sites where there is little surplus skin to repair site when removed
Identify the risk factors for squamous cell carcinoma (SCC)
UV radiation
Male sex
Fair skin
Occupational exposures; tars, oil, radiation
Immunosupression
Describe the appearance of a SCC
Often still able to produce keratin - may be a crust on top of the lesion
Can present as ‘non-healing ulcer’.
Name some histological changes in SCC
Hyperchromatism
Pleomorhphism
High nuclear:cytoplasmic ration
Loss of normal tissue architecture
Changes can be seen prior to invasion - ‘carcinoma in situ’
Where is a carcinoma in situ contained?
Within the epidermis/epithelial layer of a tissue
What is the ABCDE criteria of assessing a skin lesion?
Asymmetry
Border
Colour
Diameter
Evolving
Name some risk factors of malignant melanoma
UV radiation exposure - patterns of exposure e.g. childhood exposure
FH of melanoma
Presence of dysplastic or abundant naevi
What does the stage of a cancer mean?
The size of the tumour and how far it has spread from where it originated
What does the grade of a cancer mean?
The appearance of the cancerous cells
What is the TNM staging for cancers?
Tumour size (DEPTH)
Lymph node involvement
Metastases
