Dermatology Flashcards
Define acne vulgaris
Disorder of pilosebaceous follicles in the face and upper trunk
How does acne vulgaris clinically present?
Greasy skin with comedones (blackheads), papules and pustules.
Presents just after puberty.
Face 99%, back 60%.
Nodulocystic acne: Severe, with cysts.
What is the pathophysiology of acne vulgaris like?
1: Higher than normal sebum production (due to androgens)
2: Excessive deposition of keratin (-> comedone formation)
3: Colonisation of the follicle by Propionibacterium acnes
4: Local release of pro inflammation.
These all contribute to blocked pilosebaceous follicles. Acute inflammation through chronic acne can cause scarring of the skin.
What causes acne vulgaris?
Some genetic link.
Onset of puberty brings hormonal changes (increase in androgens).
Infection by Propionibacterium acnes also contributes.
Diet has some unclear effect.
Also worsened by stress.
Epidemiology of acne vulgaris
Almost every teenager.
Moderate-severe in about 20% of people
Diagnostic test for acne vulgaris
Usually not required
Treatments for acne vulgaris
Usually self limiting. Teenagers very sensitive.
First line: Topical agents such as keratolytics (salicylic acid), benzoyl peroxide
Second line: Low dose oral tetracycline (doxycycline)
Third line: Topical retinoid (tretinoin)
Complications of acne vulgaris
Scarring, psychosocial factors
Retinoid: Very teratogenic, adverse effect from sunlight.
Sequelae of acne vulgaris
Recurrence
Define eczema (dermatitis)
Itchy rash of the folds of the elbow/knee
Itchy rash following contact with an irritant
Types of eczema (dermatitis)
Atopic
Exogenous (contact dermatitis)
How does atopic eczema clinically present?
Itchy red rash, scaling and oozing.
Usually in folds of knee and elbow and around the neck.
How does exogenous (contact dermatitis) eczema clinically present?
Sharply demarcated skin inflammation: red, crusting and scaling,
fissures,
hyperpigmentation (if chronic)
What is the pathophysiology of atopic eczema?
It is thought that a defect in epithelial barrier function allows antigenic material and irritants to penetrate and come into contact with immune cells -> immune response.
What is the pathophysiology of exogenous (contact dermatitis) eczema?
Chemical irritants -> very noticeably demarcated lesion (as if a splash of liquid).
Type IV sensitivity reaction.
What causes atopic eczema?
Strong genetic element.
Exacerbating elements include strong detergents, pet hair and some dietary antigens.
What causes exogenous (contact dermatitis) eczema?
Exposure to irritants (usually industrial solvents, can be nickel etc)
Epidemiology of atopic eczema
Most common form
Epidemiology of exogenous (contact dermatitis) eczema
Women more than men
Diagnostic tests for both types of eczema (dermatitis)
Clinical
Treatments for atopic eczema
Avoid irritants.
Regular emollients to hydrate.
Corticosteroids (hydrocortisone).
Calcineurin inhibitors: tacrolimus (immunosuppressive)
Treatments for exogenous (contact dermatitis) eczema
Avoid irritants.
Steroid cream.
Antipruritic creams.
Complications of atopic eczema
Scratching can cause exorciations -> broken skin -> Opportunistic S. aureus or herpes simplex infection
Define psoriasis
Chronic hyperproliferative disorder with well-demarcated red scaly plaques