DERM Flashcards
Functions of the skin
1. Barrie rot infection 2> thermoregulation 3. Protection against trauma 4. Protection against UV 5. Vit D syntehsis 6. Regulate H20 loss
pH of the skin
5.5
Why is the skin pH 5.5
Allows proteases on the skin to do desquamination
What is the stratum corneum
Made of corner-desmosomes and desmosomes
What are cornel-desmosomes
Adhesion molecules that keep corneocytes together
Describe the layers of the skin
- Stratum lucidium
- Granulosum
- Spinous
- Basale
What nerve endings are found in the dermis
Meissner’s corpuscules - light touch
2. Pacinian corpuscle (vibration)
Role of keratinocytes
Produce keratin as a protective barrier
Role of Langerhans cells
Present antigens and activate T cells
Role of merkel cells
Specialised nerve endings for sensation
Common causes of itch with rash
- URTICARIA (hives)
- ATOPIC ECZMA
- Psoriasis
- Scabies
Common causes of itch with no rash
- Renal failure
- Jaundice
- Iron deficiency
- Lymphoma (hodgkin’s)
- Polycythaemia
- Pregnancy
- Drugs
- Diabetes
- Cholestasis
What is acne
Expansion and blockage of hair follicle and inflammation
Most common variant of acne
Acne Vulgaris
Pathophysiology of acne
- Hypercornfiictaion causes narrowing of hair follicle
- Increased sebum production
- Sebum is trapped which narrows follicle further
- Sebum stagnates at pit of follicle where there is no oxygen
- Anaerobic conditions allow propionibacterium acne to multiply
- P. acne breaks down triglycerides in sebum into free fatty acids = irritation, inflammation and attraction of neutrophils
- Pus formation as attract neutrophils come into the area
Whitehead vs blackhead
White - closed comedones
Black - open comedones
Clinical presentation of acne
- Whiteheads
- Blackheads
- Skin coloured papule (red spots)
- Inflammatory lesions when closed wall of comedones rupture
- Pustules (yellow spots)
- Nodules (large red bumps
Diagnosis of acne
- Skin swabs for culture
2. Hormonal test in females
Treatment of acne
- BENZOYL PEROXIDE
- CLINDAMYCIN GEL
- TAZAROTENE GEL (topical retinoid)
How does Benzoyl peroxide work
Increases skin turnover
Clears pores and reduces bacterial count
Causes dryness due to kertaolytic effect
How do topical retinoids work
Inhibit formation and reduce number of micromedones
Severe acne treatment
- ORAL DOXYCYCLINE
- ORAL MINOCYCLINE
HORMONE TREATMENT with ORAL CO-CYPRINDIOL (anti-androgen suppresses sebum productioN)
What is eczema/dermatitis
Breakdown of skin due to thinning of stratum corneum - increased risk of inflammation
What is endogenous eczema
Hypersensitivity caused (food allergies)
What is exogenous eczema
Contact dermatitis due to chemicals, sweat and abrasives
Pathophysiology of eczema
- Damaged filaggrin
2. CD4 lymphocytic activation = inflammation
Role of filaggrin
Skin barrier protein
Clinical presentation of eczema
- face and flexure surfaces of limbs
- Itchy, erythematous and scaly patches
- Dryness of skin
- Very acute lesions
RECURRENT STAPHYLOCOCCUS AUREUS INFECTIONS
Diagnosis of eczema
- Atopic dermatitis:
High serum IgE
Itchy skin for 6 months
PULS: History of involvement of skin creases Asthma or hay fever Dry skin history Childhood
Treatment of eczema
- Eductaion
- Avoid allergens
- Keep nails short
- E45 CREAM
- Topical corticosteroids
- Second line: Topical calcineurin inhibitors
How does E45 work (EMOLLIENT THERAPY)
- Traps moisture in skin to increase hydration and acts as barrier to water loss
Natural moisturising factor in corneocytes is depleted in eczema
How often is E45 applied
Every 4hours / 3 - 4 times a day
What topical corticosteroids are given as first line treatment for eczema
- CLOBETASOL PROPIONATE
- FLUCINONIDE
- CLOBETASOL BUTYRATE
- HYDROCORTISONE
used for inflamed skin
What topical calcineurin inhibitors are given
PIMECROLIMUS or TACROLIMUS ointment
How do topical calcineurin inhibitors work
- Inhibit IL 2 which reduces inflammation and do not cause skin atrophy
3rd line treatment for eczema
- CICLOSPORIN
- AZOTHIOPRINE
- ORAL PREDNISOLONE
- FLUCLOXACILLIN
- PHOTOTHERAPY with UV A
- CHLORPHENAMINE
What is psoriasis
Hyper proliferation of keratinocytes + inflammatory cell infiltration
What aged people are effected by psoriasis
ADULTS
What environmental triggers cause psoriasis
- Infection by group A strep
- Lithium
- UV
- Alcohol
- Stress
Pathophysiology of psoriasis
- T cell activation = up regulation of INF gamma, IL1,2,8
2. Increased uncontrolled proliferation of keratinocytes
Clinical presentation of psoriasis
- Pitting and onycholysis (separation of finger nail from nail bed)
Clinical presentation of chronic plaque psoriasis
- Disc shaped salmon-pink-silvery plaques on exterior surfaces of elbows and knees
- Plaques on hair margin
- Thickened epidermis
- New plaques at skin trauma sites
How is chronic plaque psoriasis treated
- E45
- CALCIPQOTRIOL CREAM (topical vit D analogues)
- HYDROCORTISONE CREAM (topical corticosteroids)
- TAZAROTENE GEL (topical retinoid)
- UV B
- COAL TAR
- DITHRANOL CREAM (anti-mitotic)
- ——SEVERE——-
1. UV A
2. DMARD (METHOTREXATE and FOLIC ACID)
3. CICLOSPORIN
Clinical presentation of flexural psoriasis
- Red, glazed non-scaly plaques
2. Confined to flexures (groin, natal cleft and sub-mammary areas)
How is flexural psoriasis treated
- HYDROCORTSIONE - causes atrophy
2nd line: CALCIPQOTRIOL CREAM (irritating so don’t use for face)