The Pathogenesis of Acne

The geometric mean count of P acnes per follicle on the skin of acne patients is around 115,000, whereas on normal skin it is practically zero. Acne patients have less linoleic acid in their sebum than do age-matched controls. This deficiency may cause the abnormal desquamation of follicular epithelial cells that leads to the formation of microcomedones and comedones.

We can use topical retinoids, such as adapalene (Differin®), tretinoin (Retin-A®, Retin-A Micro™, or Avita®), or tazarotene (Tazorac®), to correct abnormal keratinization; anti-androgen agents and isotretinoin to decrease sebum production; and antimicrobials and antibiotics to kill Acne.

To achieve optimal results, topical retinoids should be used for several months... Combination therapy with antibiotics, either topically or systemically, makes sense for most patients. Two of the most popular combinations for mild to moderate inflammatory acne are (1) adapalene, tretinoin, or tazarotene with benzoyl peroxide, and (2) topical retinoids with a benzoyl peroxide/erythromycin combination.

Pyoderma faciale and acne fulminans are fairly uncommon. Acne conglobata, however, is much less rare. Again, there is intense inflammation. Numerous deep, inflammatory nodules appear, some of which run together to form sinus tracts on the face and trunk. Scarring can be a problem, too. Isotretinoin is usually effective, though some patients may need to use systemic corticosteroids, either concomitant with or prior to isotretinoin.

If a woman has evidence of hormonal irregularities, such as abnormal periods or hirsutism, she should undergo a full hormonal work-up, and the results can help guide the choice of hormone treatment. Systemic corticosteroid therapy can be useful for those who have excessive adrenal androgen production. For those with excessive ovarian androgen production, oral contraceptives containing estrogens or progestins are the best bet.

Because the retinoid tretinoin (Retin-A) can be irritating to some patients, they should be started on a low concentration of the cream, which is available in 0.025%, 0.05%, and 0.1% concentrations, or the gel, which comes in 0.01% and 0.025% concentrations. If the patient tolerates the medication, the dose can be raised in increments.

Generally, acne begins in the pre-pubertal period - anywhere from age 8 to 13 - but it is not uncommon in girls of 7 years. The adrenal glands have matured and begin to release increased amounts of adrenal androgens. Secretion of sebum by the sebaceous gland is triggered by androgens. During this initial period, the child may develop no inflammatory comedones in the "T-zone" - the forehead, chin, nose, and par nasal areas. These precursor lesions are solely a result of increased sebum production and abnormal desquamation within the follicle. As the child becomes pubescent and the gonads mature, androgen production increases, as does sebum secretion. The follicular environment thus is conducive to the proliferation of P acnes colonies, which can instigate the development of inflammatory lesions.