Introduction to Dermatology 2 Flashcards
What external factors does the hair help protect against?
UV, things which may be crawling on us
What is the pilosebaceous unit?
the hair shaft, the hair follicle, the sebaceous gland, and the erector pili muscle
What does the pilosebaceous unit produce?
Sebum (oil)
What are the functions of the hair?
- Sexual /social interaction
- Source of epithelial and melanocyte stem cells
- Apocrine swear which is involved in thermoregulation
- Sebum production
- Protection against external factors
Where are terminal hairs found?
Scalp, eyebrows and eyelashes
Where are the vellus hairs found?
Found on the rest of the body, with the exception of the palms, soles and external genitalia, mucosal region of lips
What are the hairless genitalia in men and women?
Men - foreskin of the penis
Labia minora
What are the three stages of the hair cycle?
Anagen
Catagen
Telogen
What phase of the hair cycle most of our hair in at any given time?
The anagen phase
How long does the anagen phase of the hair cycle last?
Lasts 2-6 years
What occurs in the catagen phase?
When the hair is shrinking / regressing back into the follicle
How long does the catagen phase last?
Lasts 3 weeks
What happens in the telogen phase?
The resting phase - hair is neither growing or shrinking
During states of illness, in what phase of the hair cycle can an increase in the amount of hair in this cycle be seen?
The telogen phase
How long does the telogen phase of the cell cycle last?
3 months
What happens to the hair after the telogen phase comes to a end?
The hair detaches and is lost
What are hair follicles?
Pockets of epithelium that are continuous with superficial epidermis
What is found at the base of a hair follicle?
A dermal papilla, made of dermis
Where does the arrector pili extend from?
The surface of the dermis to a point in the follicle wall
What is the purpose of the arrector pili muscle?
When they contract, they cause the hair to stand up
What type of muscle is the arrector pili?
Smooth muscle - controlled by autonomic nervous system
What type of secretion do sebaceous glands support?
Holocrine section
Where do the holocrine sebaceous glands open into?
pilary canal
In the axillae, what type of secretion are the glands found there associated with?
Apocrine glands
What are the two parts of the hair follicle?
Infundubulum and Isthmus
From what point does the infundubulum extent to and from?
The sebaceous gland to the surface of the skin
What what points does the isthmus extend from?
Between the opening of the sebacous gland and the insertion of arrector pili muscle
What does epithelial keratinization begin with?
A lack of granular layer
What is trichilemmal keratinization?
Where is the bulge located?
Just below the sebaceous gland
What cells reside in the bulge?
hair follicle stem cells
What forms when hair follicle stem cells migrate downwards?
New lower anagen hair follicles - they enter the hair bulb matrix, proliferate and undergo terminal differentiation to form hair shaft and inner root sheath
What forms when the hair follicle stem cells migrate upwards?
Form the sebaceous gland
Why are hair follicle stem cells important in injury?
They proliferate in response to wounding, and help healing response
What is the bulb?
The lower most portion of the hair follicle which includes the follicular dermal papilla and the hair matrix
What is the matrix?
THE PRINCIPAL PLACE WHERE THE HAIR SHAFT IS BEING PRODUCED
What does the outer root sheath do?
Serves as a reservoir of stem cells
Where does the outer root sheath extend from?
From along the hair bulb to the epidermis
What is the purpose of the inner root sheath?
To guide and shape the hair
What is contained with the inner root sheath?
Follicular dermal papilla. mucopolysaccharide-rich strome, nerve fibre and capillary loop
What is the purpose of the mucopolysaccharide-rich strome found in the inner root sheath?
To give the inner root sheath strength
What do the nails protect?
The underlying distal phalanx
What are the functions of the nails?
- Protects underlying distal phalanx
- Counterpressure effect - important for walking and tactile sensation
- Increase dexterity / manipulation of small objects
- Enhance sensory discrimination
- Facilitate scratching / grooming
What is the nail plate?
The final product of proliferation and differentiation of nail matrix keratinocytes
What does the nail plate emerge from?
Proximal nail fold
What is the growth rate of the nail plate?
1-3mm a month
What is the point at which the nail plate detaches from the nail bed called?
Hyponychium
Where is the nail plate manufactured?
In the nail matrix
What is the lunula?
only visible portion of the nail matrix
Where is the nail matrix found?
Underneath the proximal nail fold, above bone of distal phalanx
How does the nail grow in the nail matrix?
Nail matrix keratinocytes differentiate, lose their nuclei and become filled with hard keratin and fill with hard keratin
What does the nail matrix contain as well as keratinocytes?
Melanocytes
Are the melanocytes found in the nail matrix active?
No
What is an erythema?
A red, raised and large area of inflammed skin
What type of disorder is Psoriasis?
An immune mediated disorder
What features characterise the most common features of psoriasis?
Sharply demarcated, scaly, erythematous plaques, silvery plaques
What are common sites for psoriasis flareups to occur?
Scalp, elbows, knees, nails, hands, feet and trunk
What causes psoriasis?
Polygenic predisposition combined with environmental triggers eg trauma, infection or medication
Describe how dermal dendritic cells are activated in the pathophysiology of Psoriasis?
Stressed keratinocytes release DNA which forms complexes with anti-microbial peptides
This induces cytokine production to activate the dermal dendritic cells
Describe how the formation of dermal dendritic cells leads to the formation of a psoriasis plaque?
dDC’s migrate to the lymph nodes, and promote the release of cytokines from Th1, Th17 and Th22 cells
These migrate into the dermis and cause further cytokine production which causes the keratinocytes to proliferate and form a psoriasis plaque
When dDC’s migrate to the lymph nodes, which T helper cells are activated?
Th1, Th17 and Th22
When stressed keratinocytes release DNA and form complexes with antimicrobial peptides, the release of which cytokines is initiated?
TNF-alpha, IL-1 and IFN-alpha
What are some clinical features of psoriasis?
- Erythemas - may appear as pigmented areas on darker skin tones
Why might you not see scales in areas of flexure?
Skin meets skin, and therefore due to friction there might not be scales present
How is it possible to get psoriasis of the nails?
nails are made of nail matrix which contains keratinocytes, so can develop psoriasis
What does psoriasis of the nails indicate?
That the patient is of increased risk of psoriatic arthiritis
What is thickening under the nail called?
Subungual hyperkeratosis
What is Onycholysis?
Detachment of the nail from the nail plate
What is Erythrodermic psoriasis?
When you have a peeling rash covering more than 95% of your body surface area
What is guttate psoriasis?
psoriasis that appears as small, round spots called papules that are raised and sometimes scaly.
What lifestyle factors worsen psoriasis?
Alcohol, smoking and other co-morbidities
What psychological conditions are you at an increased risk of when you suffer from psoriasis?
Suicide, depression and anxiety
What other areas of your body might psoriasis affect?
Mental health, joints
What are four topical therapies used to manage psoriasis?
Vitamin D analogues
Topical corticosteroids
Retinoids
Topical tacrolimus / pimecrolimus (immunosuppresants)
When are topical therapies used to manage psoriasis?
When you have small patches of psoriasis over the body
When is phototherapy chosen as a treatment for psoriasis?
When the psoriasis is too widespread over the body
What does phototherapy involve?
Using Narrow band UVB rays to treat psoriasis
What is Acitretin?
A vitamin A anaologue
What are two systemic immunosuppresive drugs that can be given to treat psoriasis?
Methotrexate
Ciclosporin
How are biologics used to treat psoriasis?
Anti-TNF, anti-IL-17 and anti-IL23 (these are all cytokines which are important in the onset of psoriasis
What is eczema?
A chronic, inflmmatory condition which typically begins during infancy or early childhood, and is often associated with other atopic disoders like asthma and rhinoconjunctivitis
What are the hallmarks of eczema
Acute inflammation of cheeks, scalp and extensors in children, and flexural inflammation and lichenification in children and adults
What is eczema cmmonly referred to as?
Dermatitis
What are some different types of eczema?
Atopic eczema, allergic contact eczema, venous stasis eczema, irritant contact dermatitis
What is the key defining principle of atopic dermatitis?
Itchy skin
What is seborrhoiec acezma?
Dandruff
What are the two components of the pathophysiology of eczema?
Barrier defects and immune dysregulation
what is the function of filaggrin?
To bind and aggregate keratin bundles and intermediate filaments to form cellular scaffolds in corneocytes
What are corneocytes?
Cells found in the stratus cornea
What happens when there is a mutation causing the filaggrin to function incorrectly?
There is reduced extracellular lipids and impaired ceramide production
Increased transepidermal water loss
Impaired protection against microbes and environmental allergens
What is transepidermal water loss?
Loss of water across the epideral barrier
how does immune dysregulation lead to eczema?
Straphylococcal superantigens overstimulate Th2 lymphocyte responses and subvert T-reg cells
What happens to the microbiome during eczema?
It is imbalanced
What are the clinical features of infantile atopic dermatitis?
Erythemaous, oedematous papules and plaques with or without vesiculation
How does the area eczema impacts change as you go from infant to child>
Changs from scalp and cheeks to affect the flexures like behind the knees and inner arms
what happens to people with pigmented skin during eczema?
Hyperpigmentation
What is lichenification?
Thickening of skin and skin lesions
What is fissuring?
When you get cracks in the skin forming
What is contact dermatitis?
When you get inflammation of the skin dur to your skin reacting with something which it has come into contact with
What is impetiginisation?
When there is a superficial infection of the skin, usually seen with a gold crust and a Staphylococcus aureus infecion
How does venous stasis eczema aris?
Due to a buildup of fluid due to venous incompetance of the skin which compromises the barrier, leading to trans epidermal waterloss
How do you treat Venous stasis eczema?
Stockings and compression - responds to steroids but doesn’t stay responding
What condition does someone have when they present with monomorphic punched out erosions with their eczema?
Eczema herpeticum
Which type of eczema is considered an emergency?
Eczema herpeticum
What soap should eczema patients use?
Dermol 500, with cold showers
What does soap do to eczema patients?
Aggrevates the barrier defect
What is nipple eczema until proven otherwise?
Pagets disease of the nipple - presents in a very similar manner to eczema so it is always important to be biopsied
What can pagets disease suggest?
Breast cancer
When might a biopsy of atopic eczema be taken?
If it is on the nipple, or there could be a cutaneous lymphoma
What is PUVA used for?
Treating hand dermatitis and some forms of psoriasis
What topical therapies can be used for the treatment of eczema?
Topical corticosteroids and topical tacrolimus
What unit is used to describe the amount of topical steroids which should be used to treat eczema?
Fingertip units
What can the over use of topical steroids cause?
Tachphylaxis and adverse effects
What is the order of topical steroids in terms of potency?
Hydrocortisone Clobetasone Betamethasone Momentasone Clobetasol (Dermovate)
Which areas are bethmethasone and momentasone used in?
The non-flexure areas of the skin like limbs and trunk in adults
Which topical steroid is used when there is lichenification of the skin?
Clobetasol (Strongest)
What are the rare effects of topical immunomodulatories?
skin atrophy, folliculitis, exacerbation of acne and rosacea, infection
What are the very effects of topical immunomodulatories?
Perioral dermatitis (around mouth), rebound syndrome and allergy to steroid
What are the extremely rare effects of topical immunomodulatories?
hormonal imbalance, suppression of hypothalamic-pituitary-adrenal axis, hirsuitism
What is hirsuitism?
condition in women that results in excessive growth of dark or coarse hair in a male-like pattern — face, chest and back
What is perioral dermatitis?
SKIN RASH around the mouth
which type of eczema are retinoids used to treat?
hand Dermatitis
What are some drugs used for systemic immunosuppression in the treatment of eczema?
Methotrexate
Ciclosporin
Azathioprine
Mycophenolate mofetil
what biologics are used in the treatment of eczema?
Duplimab - Anti-IL-4alpha and anti-IL13
When can biologics be used to treat eczema?
When patients have not responded to other treatments
