Acne, scabies & lice (skin 8) Flashcards
what is the difference between psoriasis and eczema?
psoriasis:
- chronic, lifelong disease
- common in adults
-hederdiatry
-characterised by thick, silver scales
eczema
- condition that can come and go
- common in children
- thought to be environmental
-skin being red and imflammed
Atopic dermatitis (eczema)
aetiology
pathophysiology
clinical features
treatment
aetiology: Idiopathic, genetic; family history of atopy; Environmental triggers
Pathophysiology: Abnormal IgE activity mediated by B lymphocytes
clinical features:Dry scaly thickened skin often on flexural surfaces; common in children
Treatment: Corticosteroid creams; emollients; wet dressing
Psoriasis
aetiology
pathophysiology
clinical features
treatment
Idiopathic, genetic; triggered by trauma, stress, infection
Abnormal T cell activity; excess / hyperproliferation of skin cells
Skin plaques “silvery” scales; rough red and raised skin; common on extensor surfaces
Emollients; Vitamin D analogues and corticosteroid; UV light; coal tar; monoclonal antibodies
Contact dermatitis; allergic / irritant
aetiology
pathophysiology
clinical features
treatment
Contact leading to irritation; irritant (most people react to) or allergic (some people respond to)
Abnormal T cell activity mediated by T lymphocytes
Red / burning itchy vesicles on skin surface. Irritant located at site of exposure (but may spread); allergic not localised to exposure site
Avoid irritant; corticosteroid; calamine; antihistamine for itch
what are the hazards for emollient?
Emollients are not flammable in themselves, or when on the skin.
But advise patients to avoid naked flames & halogen heaters near clothing / bedding / dressings
what are emollients?
why does it not have an API ?
Lots of options available:
Creams, ointments, gels, lotions, sprays, washes, (and bath / shower additives)
Emollients containing API’s not generally recommended
Increased risk of skin reactions.
But may be useful for some people.
- emollients are prescribed according to the dryness of the skin and individual preferences/ tolerance.
-creams and lotions = red, inflamed skin ( evaporation of water based products can cool the skin) - do NOT advice aqueous cream
- ointment = dry skin which is NOT inflamed.
- recommend an emollient with a pump to minimize the risk of bacterial contamination and ease the use.
-For emollients that come in pots, advise that using a clean spoon or spatula (rather than fingers) to remove the emollient helps to minimize contamination.
Emollients can replace soap in people with dry skin requiring treatment.
Ointments dissolved in hot water are suitable soap substitutes.
Bath additives and shower products are an option for people with extensive areas of dry skin
Evidence to support their use is limited and no consensus on their benefit
If bath emollients are used, it is essential that they do not replace standard emollients.
The effectiveness and acceptability of a particular emollient may vary with time.
If the person feels that a particular product has become unsuitable for them (or if they have developed sensitivity to it), recommend an alternative emollient.
It may be necessary to try a range of emollients before the person settles on the best combination.
Dispense generous amounts (eg 500 g) to be used regularly (often four times daily). - To encourage appropriate usage
what are the adverse effects from emoillients?
Skin reactions are the most common adverse effects of emollients.
Due to skin sensitising additives;
perfumes, preservatives, and biological components, such as lanolin (although newer hypoallergenic formulations of lanolin are less problematic).
If a skin reaction occurs, stop the emollient and use a different one.
If the person has had previous skin reactions to emollients, consider testing a small quantity on the skin before widespread application.
If sensitivity to emollients is a known problem, prescribe a cream with few additives, or an ointment (ointments do not require preservatives and generally have less excipients), to reduce the chance of a further reaction.
The occlusive effect of ointments can cause folliculitis. If this occurs, stop the ointment (consider switching to a cream), and prescribe an antibiotic, if necessary.
what is the advice for emoillents?
Advise to use liberally and frequently, even when their skin appears improved or is clear.
- It is recommended that 250–500 g of emollient be applied every week.
- Frequency of application will vary, but for very dry skin, application of an emollient every 2–3 hours is normal.
To facilitate frequent application, the person should consider keeping separate packs of emollients at work or school.
Important to use emollients during or after washing.
Emollients should be applied by smoothing them into the skin along the line of hair growth, rather than rubbing them in.
Can use better tolerated products (such as creams and lotions) during the day, and ointments (which are usually poorly tolerated) at night.
Emollients should not be shared with other people as they can become contaminated with bacteria.
Avoid the use of soaps, detergents, and bubble bath when washing; use a suitable soap substitute instead
(People who need to use large quantities (more than 100 g) of any paraffin-based product should regularly change clothing, bedding, or dressings which become impregnated with the product and keep away from naked flames, as there is a risk of fire)
what is acne vulgaris characterised with?
Skin condition characterised by formation of:
comedones (blackheads and whiteheads),
papules (pinheads), skin elevation, no fluid 5-10 mm diameter
nodules (like a papule but bigger than 5-10 mm)
cysts (cavity usually containing fluid)
Can be inflammatory or non-inflammatory
Commonly appears on face and shoulders, but may occur on trunk, arms and legs
what causes acne vulgaris?
Occurs when hair follicles and associated sebaceous gland become obstructed with sebum/dead keratinocytes. Can become infected with normal skin anaerobe, Cutibacterium acnes (name recently changed from Propionibacterium acnes), leading to inflammation
Lipases from C. acnes metabolise triglycerides into free fatty acids, which irritate the follicular wall. Pustules occur when active C. acnes infection causes inflammation within the follicle.
Nodules/cysts appear when inflamed follicles rupture
who does acne vulgaris happen to?
triggers
Commonly occurs in adolescence but can arise at any age, including as an infant
Tends to run in families
Most common trigger is puberty, when get surges in androgen that stimulates sebum production and hyperproliferation of keratinocytes.
Other triggers include:
- hormonal changes in pregnancy or menstrual cycle
- occlusive cosmetics, cleansing agents and clothing
- excessive humidity and sweating
- stress
-certain drugs (e.g. oral contraceptives, corticosteroids,
testosterone, oestrogen, and phenytoin)
what are the classification of acne vulgaris?
Classification of Acne Severity
Mild
< 20 comedones, or < 15 inflammatory lesions, or < 30 total lesions
Moderate
20 to 100 comedones, or 15 to 50 inflammatory lesions, or 30 to 125 total lesions
Severe
> 5 cysts, or total comedone count > 100, or total inflammatory count > 50, or > 125 total lesions
what is the treatment for acne?
Main aim is to reduce sebum production, comedone formation, inflammation and infection
Selection of treatment depends on severity
Affected areas should be cleansed daily (extra washing, scrubbing, use of antibacterial soaps confer no added benefit)
Changes in diet unnecessary
Mild to moderate usually treated topically
Moderate to severe usually systemic antibiotics (or when topicals failed)
Severe refer to dermatologist; may need aggressive therapy e.g. Isotretinoin
what are treatment options available for mild acne?
Comedones and inflamed lesions respond well to benzoyl peroxide.
- Usually start low dose and increase if necessary
- 2.5 to 5% then up to 10% - Possible local skin irritation, usually subsides with time
- If no response in 2 months, then consider topical anti-bacterial
As a peroxide (as in hair bleach), is metabolised to benzoic acid and oxygen free radicals
- Benzoic acid decreases pH
- Oxygen free radicals are bactericidal, and can also break down keratin so are comedolytic
- Benzoyl peroxide also available with clindamycin (antimicrobial)
Azelaic acid an alternative
- Anti-microbial and anti-comedonal
- Less likely to cause local irritation than benzoyl peroxide - Patients may prefer, especially for face
Topical retinoids (e.g. tretinoin / adapalene) effective for comedones and inflamed lesions
- Can be irritant, initially giving redness/peeling
- Avoid in pregnancy, avoid sun exposure
Others:
Topical antibacterials (clindamycin / erythromycin) not widely used, tend to be ineffective used alone
Salicylic acid preparations are available
- Keratolytic
- Not as suitable as other preparations
Sulphur / abrasive formulations available but not considered beneficial
Topical corticosteroids should NOT be used (increases sebum secretions)
what is the treatment for moderate acne?
Moderate acne - responds best to oral systemic therapy with
antibiotics e.g. tetracycline, minocycline, doxycycline, erythromycin.
Tetracycline common first choice 500mg bd (between meals and at bedtime)
Expect maximum improvement after 4-6 months
If no benefits after first 3 months, consider swapping to e.g. doxycycline
what is the treatment for severe acne?
Severe acne - oral isotretinoin (1mg/kg daily for 16-20wks).
Isotretinoin almost always effective but has serious side effects
e.g. dryness of mucous membranes, depression, arthralgias, birth defects, elevated lipids.
what is scabies?
Infestation of the skin with the mite, Sarcoptes scabiei
Obligate human parasite that lives in burrowed tunnels in
stratum corneum. Burrows are a few mm - 1cm long.
Tiny black papules (the mite) often visible at one end
usually in between the fingers, wrist
rash can appear- armpits, stomach, groins, knees , bum, elbows, back
how is scabies transmitted?
primary risk factors?
Easily transmitted from person-to-person through
physical contact. Animal transmission also occurs
Primary risk factor is crowded conditions (schools,
Shelters, some households). No clear association with
poor hygiene
Causes intensely pruritic lesions, usually worse at night,
with erythematous papules and burrows in web areas of
hands, wrists, waistline and genitals
Infestations occur worldwide.
Severity related to patient’s immune system, not geography
what are different forms of scabies?
Classic scabies - erythematous papules first appear in finger web spaces, wrists, elbows, axillary folds, waistline. Face remains unaffected in adults.
Crusted (Norwegian) scabies - due to impaired immune system
Nodular scabies - more common in infants/young
children. May be due to hypersensitivity to retained organisms
Bullous scabies - occurs in children and also in elderly
Scalp scabies - occurs in infants and immuno- compromised patients. Can mimic seborrhoeic eczema
Scabies incognito - widespread atypical form resulting from application of topical corticosteroids.
what are treatment of scabies
***First line treatment is with topical scabicides. Permethrin
is drug of choice.
Apply to entire body from neck down and wash it off after 8-14 h. Repeat treatment after 7d.
For infants and young children, permethrin should be applied to
the head and neck, avoiding periorbital and perioral regions.
Special attention should be given to fingernails, toenails, and
umbilicus. Mittens on infants can keep permethrin out of mouth
***Lindane not recommended in children < 2 yr or in patients with
a seizure disorder because of potential neurotoxicity
Precipitated sulphur 6 - 10% in petrolatum, applied for 24 h for 3
consecutive days, is safe and effective.
***Ivermectin is indicated for patients who do not respond to
topical treatment, are unable to adhere to topical regimens, or
are immunocompromised with Norwegian scabies.
Close contacts should also be treated, and personal items (e.g. towels, clothing, bedding) should be washed or isolated for at least 3 days.
***Pruritus can be treated with corticosteroid ointments and/or
oral antihistamines
Symptoms and lesions take up to 3 wk to resolve despite killing
off the mites.
what is the examination of scabies?
Diagnosis based on examination and skin scrapings
skin scraping = diagnose persistent scabies
what is lice (pediculosis)
how is transmitted
symptoms?
Wingless, blood-sucking insects, 2-5mm in length, that can infest scalp (Pediculus humanus var. capitis), body (P. humanus var. corporis), pubis (crab lice; Phthirus pubis), eyelashes
All three kinds of lice differ substantially in morphology and clinical features. Head/pubic lice live on body; body lice in clothing. All occur worldwide.
Lice typically can survive for up to 30 days without a human host
Head lice transmitted by close contact; body lice in cramped, crowded conditions; pubic lice (crabs) by sexual contact
Symptoms, signs, diagnosis, and treatment differ by location of infestation
Can act as vectors for other diseases e.g. typhus
who is headlice most common in
how is it transmitted
diagnosis
Most common in girls aged 5-11 but can affect almost anyone; rare in Afro-Caribbeans
Typically infests hair, scalp, eyelashes, eyebrows, beard
Easily transmitted by close contact (households, classrooms); may be ejected from hair by static electricity or wind.
Transmission also by sharing combs, brushes (hats unproven)
No association with poor hygiene/low socioeconomic status
Active infestation usually involves <20 lice. Causes severe pruritus
Diagnosis - detected by thorough combing-through of wet hair from scalp with fine-toothed “lice” comb; lice usually found at back of head/behind ears. Can be difficult to see.
what is body lice?
diagnosis
Primarily live on bedding/clothing
Found in crowded conditions e.g. barracks and in people of low socioeconomic status
Transmitted by sharing contaminated clothing and bedding
Intense pruritis
See small red puncta caused by
bites. Esp. common on shoulders,
buttocks and abdomen
Diagnosis is by demonstration of nits/
Lice in clothing, esp. at seams
what is the treatment of headlice
Head Lice
Advice regularly updated in light of local resistance patterns.
Treat all family members
Mechanical removal (wet combing) avoids resistance / irritation by chemicals. Use “nit comb” on wet hair (conditioned may help). Comb whole scalp (esp. behind ears) at 4 day intervals for 2 weeks; eggs may hatch between combing.
Dimeticone (4%) - Apply to dry hair and scalp, allow to dry naturally, wash off after 8h. Repeat after 7 days.
Malathion (0.5%) - Apply to dry hair and scalp, allow to dry naturally, wash off after 12 h. Repeat after 7 days. Unpleasant odour. Resistance reported
Permethrin – Active but not recommended for head lice.
what is the treatment for body lice
Body Lice
Topical treatment of no use since body lice are found in clothing.
Treat pruritus and secondary infection
what is the treatment for pubic lice (crab lice)
Pubic Lice (crab lice)
Malathion. Apply 0.5% aqueous preparation over whole body, dry naturally, wash off after 12h. Repeat application after 7 days
Permethrin. Apply 5% cream over whole body, dry naturally, leave 12h or overnight, wash off. Repeat after 7 days
what is the treatment for eyelashes lice
Eyelashes
Petrolatum ointment. Apply 3–4 times/day for 8–10 days. Fluorescein drops 10–20%. Applied to the eyelids. Provides immediate pediculocidal effect.
