holocrine secretion of sebum

Functions of sebum

1. lubricates and waterproofs the skin, and protects it

from drying

2. mildly bactericidal and fungistatic.

Free sebaceous glands may be found in the eyelid

(meibomian glands), mucous membranes (Fordyce

spots), nipple, perianal region and genitalia.

especially dihydrotestosterone, stimulate sebaceous

gland activity.

Human sebaceous glands contain 5a-reductase, 3a-

and 17a-hydroxysteroid dehydrogenase, which

convert weaker androgens to dihydrotestosterone,

which in turn binds to specific receptors in

sebaceous glands, increasing sebum secretion.

The sebaceous glands react to maternal androgens

for a short time after birth

disorder of the pilosebaceous apparatus

characterized by comedones, papules, pustules,

cysts and scars.

all teenagers have some acne (acne vulgaris)

affects the sexes equally

ages of 12 and 14 years, tending to be earlier in

females.

Pathological factors

Sebum

Sebum excretion is increased. However, this alone need not cause acne

Hormonal

Androgens (from the testes, ovaries, adrenals and sebaceous glands themselves) are

the main stimulants of sebum excretion,

Poral occlusion

Both genetic and environmental factors (e.g. some cosmetics) cause the epithelium to

overgrow the follicular surface.

Follicles then retain sebum that has an increased concentration of bacteria and free

fatty acids

Rupture of these follicles is associated with intense inflammation and tissue damage

Bacterial Propionibacterium acnes

normal skin commensal, plays a pathogenic part

Genetic

The condition is familial in about half of those with acne

1. Infantile acne

follow transplacental stimulation of a child’s sebaceous glands by maternal androgens.

2. Mechanical

Excessive scrubbing, picking, or the rubbing of chin straps or a fiddle

3. Acne associated with virilization

4. Acne accompanying the polycystic ovarian Syndrome

5. Drug-induced

Corticosteroids, androgenic and anabolic, steroids, gonadotrophins, oral contraceptives, lithium, iodides, bromides, antituberculosis and anticonvulsant therapy can all cause an acneiform rash.

6. Tropical, Heat and humidity

7. Acne due to cosmetics

Mostly in face, shoulders, upper chest and back.

Seborrhoea is often present

Open comedones (blackheads) because of the plugging by keratin and sebum of the pilosebaceous orifice

Closed comedones (whiteheads), caused by overgrowth of the follicle openings by surrounding epithelium

Inflammatory papules, nodules and cysts

Depressed or hypertrophic scarring

post-inflammatory hyperpigmentation

Psychological depression is common

Acne Conglobate

is severe form of acne

abscesses or cysts with intercommunicating sinuses that contain thick serosanguinous fluid or pus

On resolution, it leaves deeply pitted or hypertrophic scars, sometimes joined by keloidal bridges

Infantile Acne

present at or appears soon after birth and may last up to 3 years

Fulminans Acne

conglobate acne is accompanied by fever, joint pains and a high erythrocyte sedimentation rate (ESR)

Excoriated Acne

Late onset Acne

Women, limited to the chin, Nodular and cystic lesions predominate

It is stubborn

Tropical Acne

Drug-induced Acne

Hormonal induced Acne

Acne vulgaris clears by the age of 23–25 years in

90% of patients

5% of women and 1% of men still need treatment in

their thirties or even forties.

No need usually

Cultures are occasionally needed to exclude a

pyogenic infection, an anaerobic infection or Gram-

negative folliculitis

exclude an androgen-secreting tumour of the

adrenals, ovaries or testes, and to rule out

congenital adrenal hyperplasia caused by 21-

hydroxylase deficiency, polycystic ovarian syndrome

Rosacea

Pyogenic folliculitis

Hidradenitis suppurativa

Pseudofolliculitis barbae

1. General measures

regular encouragement worthwhile

underlying cause should be removed or treated.

2. Local treatment

3. Systemic treatment

Antibiotics

Hormonal

Regular gentle cleansing with soap and water to remove surface sebum.

Benzoyl peroxide

Is an antibacterial agent

most effective for inflammatory lesions not affected by propionibacterial antibiotic resistance

start with a 2.5% or 5% preparation, moving up to 10% if necessary.

Retinoids.

normalize follicular keratinization

down-regulate TLR2 expression

reduce sebum production

effective against comedones

Side effects

skin irritation and photosensitivity

applied overnight on alternate nights

stop temporarily if irritation

worth increasing the strength of tretinoin after 6 weeks if it has been well tolerated

Contraindication

Concomitant eczema and Pregnant women

Azelaic acid bactericidal for P. acne Have an anti-inflammatory effect inhibits the formation of comedones It should be applied twice daily, but not used for more than 6

months at a timeTopical antibiotics topical clindamycin, erythromycin and sulfacetamide antibacterial resistance of P. acnes is a most erythromycin-

resistant strains being cross-resistant to clindamycin Combining antibiotics with benzoyl peroxide reduces P. acnes

numbers and the likelihood of resistant strains Emerging The addition of zinc acetate complex to erythromycin enhances

the antibiotic’s anti-inflammatory effect Cosmetic camouflage

Oxytetracycline and tetracycline.

starting dosage for an adult is 500 mg twice daily, but up to 1.5 g/day may be needed in resistant cases.

Used not less than 3 months and may be needed for 1–2 years, or even longer.

It should be taken on an empty stomach, 1 h before meals or 4 h after food, as the absorption of these tetracyclines is decreased by milk, antacids and calcium, iron and magnesium salts.

maintenance dosage being 250–500 mg/ day.

serious side-effects are rare, although candidalvulvovaginitis may force a change to a narrower spectrum antibiotic such as erythromycin.

Minocycline

50 mg twice daily or 100 mg once or twice daily is now preferred by many dermatologists

Absorption is not significantly affected by food or drink.

Minocycline is much more lipophilic than oxytetracycline and so probably concentrates better in the sebaceous glands.

can cause abnormalities of liver function and a lupus-like syndrome.

Rarely, the long-term administration of minocycline causes a greyishpigmentation, like a bruise, especially on the faces of those with actinic damage and over the shins.

Doxycycline

100 mg once or twice daily is a cheaper alternative to minocycline

more frequently associated with phototoxic skin reactions.

Contraindications

Tetracyclines should not be taken in pregnancy or by children under 12 years as they are deposited in growing bone and developing teeth, causing stained teeth and dental hypoplasia.

Erythromycin Is the next antibiotic of choice is preferable to tetracyclines in women who might become

pregnant. Its major drawbacks are nausea and the widespread

development of resistant Proprionibacteria, which leads to therapeutic failure.

Trimethoprim with or without sulfamethoxazole by some as a third-line antibiotic for acne, when a

tetracycline and erythromycin have not helped. White blood cell counts should be monitored.

Ampicillin is another alternative.

Isotretinoin

is an oral retinoid

inhibits sebum excretion, the growth of P. acnes and acute inflammatory processes.

reserved for severe nodulocystic acne, unresponsive to the measures outlined above.

It is routinely given for 4–6 months only, in a dosage of 0.5–1 mg/kg body weight/day

A full blood count, liver function tests and fasting lipid levels should be checked before the start of the course, and then 1 and 4 months after starting the drug.

Isotretinoin is highly teratogenic

Effective contraception must be taken for 1 month before, throughout and for 1 month after treatment.

Tests for pregnancy are carried out monthly while the drug is being taken only a single month’s supply of the drug should be prescribed at a time

Treatment should start on day 3 of the patient’s next menstrual cycle following a negative pregnancy test.

Other side-effects of isotretinoin include:

1. Depression rarely lead to suicide

2. a dry skin, dry and inflamed lips and eyes, nosebleeds

3. facial erythema, muscle aches

4. hyperlipidaemia and hair loss

these are reversible and often tolerable, especially if the acne is doing well.

5. Rarer and potentially more serious side-effects include changes in night-time vision and hearing loss

Rosacea affects the face of adults, usually women.

peak incidence is in the thirties and forties, it can also be seen in the young or old.

It may coexist with acne but is distinct from it.

The cause is still unknown.

Rosacea is often seen in those who flush easily in response to warmth, spicy food, alcohol or embarrassment. No pharmacological defect has been found that explains these flushing attacks.

Psychological abnormalities, including neuroticism and depression, are more often secondary to the skin condition than their cause.

Sebum excretion rate and skin microbiology are normal

The cheeks, nose, centre of forehead and chin are most commonly affected

the periorbital and perioral areas are spared

Intermittent flushing is followed by a fixed erythemaand telangiectases.

Discrete domed inflamed papules, papulopustulesand, rarely, plaques or nodules develop.

no comedones or seborrhoea.

It is usually symmetrical.

Its course is prolonged, with exacerbations and remissions.

Blepharitis

conjunctivitis

Keratitis

Rhinophyma

Lymphoedema, below the eyes and on the forehead

Acne

Rosacea differs from it by:

1. its background of erythema and telangiectases

2. absence of comedones

3. distribution of the lesions is central face but not the trunk.

4. usually appears after adolescence.

Sun-damaged skin with or without acne cosmeticacauses most diagnostic difficulty

Remember, rosacea affects primarily the central, less mobile parts of the face, whereas sun damage and acne cosmetica are more generalized over the face

The flushing of rosacea can be confused with:

1. menopausal symptoms

2. carcinoid syndrome

3. Superior vena caval obstruction

Seborrhoeic eczema

perioral dermatitis

systemic lupus erythematosus

photodermatitis

they do not show the papulopustules of rosacea

Rosacea and topical steroids go badly togetherPapulopustular rosaceaSystemic tetracyclines as for acne are the traditional treatment and are

usually effective. Erythromycin is the antibiotic of second choice. Courses should last for at least 10 weeks and, after gaining

control with 500–1000 mg/day, the dosage can be cut to 250 mg/day

The condition recurs in about half of the patients within 2 years, but repeated antibiotic courses, rather than prolonged maintenance ones, are generally recommended

Rarely, systemic metronidazole or isotretinoin is needed for stubborn rosacea

Topical

Topical 0.75% metronidazole gel, 15% azelaic acid and sulfacetamide/sulphur lotions applied once or twice daily

are nearly as effective as oral tetracycline and often prolong remission

Sunscreens help if sun exposure is an aggravating factor

changes in diet or drinking habits are seldom of value