Dermatology Flashcards
Define…
i) Whiteheads.
ii) Blackheads.
iii) Papules.
iv) Macules.
v) Vesicular.
vi) Bulla.
vii) Pustules.
i) Closed comedones.
ii) Open comedones.
iii) Elevated, red, small pimple.
iv) Area of skin decolouration.
v) Small cavity, primarily filled with clear fluid.
vi) Large blister, clear fluid.
vii) Small blister with purulent fluid (pus).
What are the common causes of an itch…
i) with a rash?
ii) without a rash?
i) Atopic dermatitis, psoriasis, scabies.
ii) Renal failure, jaundice, lymphomas.
ACNE VULGARIS
What is the pathophysiology of acne vulgaris?
- Hair follicle narrows > hypercornification (corneodesmosomes blocking entrance to hair follicles) results in increased sebum production (greasy skin).
- Some sebum trapped in narrow hair follicle, stagnates at pit of follicle as no oxygen.
- Anaerobic conditions for Propionibacterium acnes to multiply + breakdown triglycerides in sebum into free fatty acids > irritation, inflammation + neutrophil attraction.
- Leads to pus formation + further inflammation.
ACNE VULGARIS
What is the aetiology of acne vulgaris?
- Infection by P. acnes.
- Worsened by stress.
- Typically starts in adolescence + resolves in mid-20s, increased androgens during puberty.
ACNE VULGARIS
What is the clinical presentation of acne vulgaris?
- Whiteheads + blackheads.
- Papules.
- Pustules.
- Nodules.
- Commonly found on face, chest + upper back.
ACNE VULGARIS
What are the complications of acne vulgaris?
- Scars.
- Erythematous macules.
- Psychological factors.
ACNE VULGARIS
What are the investigations for acne vulgaris?
- Usually clinical.
- Skin swabs for microscopy + culture.
ACNE VULGARIS
What is the treatment for mild acne vulgaris?
- Avoid over-washing, don’t pick at it, healthy diet.
- Topical keratolytics (benzoyl peroxide), retinoids (tazarotene gel) + Abx (erythomycin gel).
ACNE VULGARIS
What is the treatment for moderate acne vulgaris?
- Low dose oral Abx like doxycycline.
- Hormone treatment in women with no C/I to oral contraceptive.
ACNE VULGARIS
What is the treatment for severe acne vulgaris? What must be avoided in pregnancy?
- Oral retinoid like isotretinoin.
- Retinoids are C/I in pregnancy as severe teratogen.
ATOPIC DERMATITIS
What is the pathophysiology of atopic dermatitis?
- Damaged filaggrin (skin barrier protein), allows antigenic material + irritants to penetrate + come into contact with immune cells initiating a response.
- Breakdown of skin due to thinning of stratum corneum caused by reduced corneodesmosomes meaning increased risk of inflammation.
ATOPIC DERMATITIS
What is the aetiology of atopic dermatitis?
- Significant hereditary predisposition, common in early childhood.
- Exacerbating factors are infection, strong detergents, cats/dogs + stress.
ATOPIC DERMATITIS
What is the clinical presentation of atopic dermatitis?
- Itchy, erythematous + scaly patches.
- More common in flexures such as front of elbows, ankles, behind knees.
- Vesicles + bullae.
- Oozing.
- Dry skin.
ATOPIC DERMATITIS
What is the main complication of atopic dermatitis?
- Scratching can lead to broken skin + opportunistic S. aureus or herpes simplex infection, can cause weeping.
ATOPIC DERMATITIS
What are the investigations for atopic dermatitis?
Clinical... - Itchy skin condition in past 6 months. - Hx of dry skin, asthma/hayfever. - Skin creases involved, childhood onset. High serum IgE
ATOPIC DERMATITIS
What is the generic treatment for atopic dermatitis?
- Avoid irritants.
- Emollient therapy like E45 cream to trap moisture in skin + increase hydration, acts as an artificial permeability barrier preventing water loss.
- Bath soap substitutes.
ATOPIC DERMATITIS
What is the first line treatment for atopic dermatitis?
- Low potency topical corticosteroids (hydrocortisone) on face + more potent steroids (betamethasone) on body/soles.
- Topical immunomodulators like tacrolimus to help sensitive areas.
ATOPIC DERMATITIS
What is the second line + adjuvant treatment for atopic dermatitis?
- UV phototherapy, short courses of oral prednisolone, Abx.
- Bandages, oral anti-histamines.
CONTACT DERMATITIS
What is the pathophysiology of contact dermatitis?
- Chemical irritants cause very noticeably demarcated lesion.
- Type IV hypersensitivity reaction, delayed type sensitivity, cell-mediated response.
CONTACT DERMATITIS
What is the aetiology of contact dermatitis?
- Exogenous exposure to irritants like chemicals + sweat.
CONTACT DERMATITIS
What is the clinical presentation of contact dermatitis?
Sharply demarcated skin inflammation…
- Red, crusting + scaling.
- Hyperpigmentation if chronic.
Itching.
CONTACT DERMATITIS
What are the investigations + treatment for contact dermatitis?
- Patch testing, suspected allergen placed in skin contact.
- Avoid irritants, steroid creams for short periods, antipruritic agents for symptomatic relief.
PSORIASIS
What is the pathophysiology of psoriasis?
- Increased numbers of corneodesmosomes leading to thickening of stratum corneum.
- T-cell activation results in upregulation of Th1-type T cell cytokines (TGF/TNF-alpha) leading to hyerproliferation of keratinoctes in the epidermis.
PSORIASIS
What is the aetiology of psoriasis?
Polygenic. Dependent on environmental triggers... - Group A strep. - Drugs like lithium. - UV light, alcohol, stress.
PSORIASIS
What are the associated nail changes in psoriasis?
- Pitting.
- Onycholysis (separation of finger from nail bed).
PSORIASIS
What is the clinical presentation of chronic plaque psoriasis?
- Well-demarcated, salmon-pink silvery scaling lesions on extensor surfaces (knee, elbows).
- Scalp involvement, most often at hair margin.
- New plaques at sites of skin trauma (Kobner phenomenon).
PSORIASIS
What is the clinical presentation of flexural psoriasis?
- Red glazed, non-scaly plaques confined to flexures (groin, sub-mammary areas).
PSORIASIS
What is the clinical presentation of guttae (‘raindrop-like’) psoriasis?
- Most commonly children/young adults.
- Explosive eruption of very small circular/oval plaques over trunk about 2 weeks post-strep sore throat.
PSORIASIS
What is the clinical presentation of erythrodermic + pustular psoriasis?
- Most severe + potentially life threatening.
- Widespread intense inflammation of skin which may be associated with malaise, pyrexia + circulatory dsiturbances.
PSORIASIS
What is the first line treatment of psoriasis?
- Reassurance with emollients, avoid triggers.
- Topical therapy with vitamin D analogues (calcipotriol), corticosteroids.
PSORIASIS
What is the second line treatment of psoriasis?
- Phototherapy with UVA radiation.
PSORIASIS
What is the third line treatment of psoriasis?
- Immunosuppression with methotrexate or biological agents like TNF-alpha blockers + monoclonal antibody.
- Used in resistant disease or severe erythrodermic/pustular psoriasis.