Infantile acne

Infantile acne is a form of acne that appears on the skin of babies, usually between about one month and one year of age. It causes blackheads and whiteheads (comedones), red bumps (papules), pus-filled spots (pustules) and, in more severe cases, deep nodules and cysts, mostly on the cheeks. It is more common in boys, and most cases are mild to moderate.^[1:1] It is distinct from neonatal acne, which appears in the first weeks of life and clears on its own.^[2]

The cause is not fully understood. Sources describe a genetic predisposition combined with sensitivity of the skin's oil glands to hormones, though they disagree on how much hormones contribute.^[3:1][2:1] Mild cases are treated with creams applied to the skin. Severe cases can leave permanent scars and may need oral medication, including isotretinoin, which is used off-label at this age.^[4:1]

Definition and age of onset

Definitions of the age range vary slightly between sources. DermNet describes true infantile acne as affecting children from six weeks to one year of age.^[3] Gencler and colleagues place onset between one and 12 months, occasionally up to 14 to 16 months.^[2:1] A 2023 case report gives one to 16 months.^[4] In a retrospective series of 29 patients, onset ranged from six to 16 months, with a median of nine months.^[1:1]

Infantile acne is separated from two earlier-onset conditions:

The descriptions of neonatal acne and infantile acne in the table follow Gencler and colleagues.^[2] Neonatal cephalic pustulosis is thought to involve an inflammatory reaction to Malassezia yeast rather than to oil-gland activity. In a prospective study of 56 newborns, 37 developed the condition. Of the moderately affected infants, 78% had Malassezia-positive skin cultures, compared with 32% of infants without pustules.^[5:1]

Signs and symptoms

Infantile acne can include comedones, inflamed papules and pustules, nodules and cysts.^[3] It usually affects the cheeks and sometimes the forehead and chin.^[3] Gencler and colleagues also list the chest and back, and note that the severe form known as acne conglobata is rarely seen.^[2]

In the 29-patient series, severity was mild in 24%, moderate in 62% and severe in 14%, and 59% of patients had a mainly inflammatory presentation.^[1:1] Of those 29 patients, 24 were boys and five were girls.^[1:1]

Causes

The cause of infantile acne is unknown. DermNet states that it is thought to be genetic in origin and is not usually due to excessive testosterone or other androgenic (male-type) hormones.^[3:1] Gencler and colleagues instead attribute it to sensitivity to circulating hormones from the adrenal glands and gonads. They point to continued fetal adrenal activity, which raises levels of the hormones DHEA and DHEAS, and to high testicular androgen levels in boys up to about age one. They also describe a significant genetic predisposition.^[2:1]

These accounts are not necessarily in conflict: a skin that reacts strongly to ordinary hormone levels would produce acne without any measurable excess of hormones. The sources reviewed here do not settle the question. Comparing hormone levels and skin sensitivity in affected and unaffected infants would be one way to test it.

Evaluation

Most infants need no laboratory testing. Gencler and colleagues advise measuring bone age and hormone levels (including FSH, LH, testosterone, DHEA, DHEAS, 17-hydroxyprogesterone, prolactin and an ACTH stimulation test) when acne is persistent or severe, or when there are signs of excess androgens.^[2:2] Santos and colleagues call androgen testing mandatory for refractory cases, while noting that most cases are not related to an underlying endocrine disease.^[4:1]

DermNet notes that acne in older prepubertal children, aged two to six years, is more strongly linked to raised androgens. It may signal conditions such as congenital adrenal hyperplasia, Cushing syndrome, precocious puberty or an androgen-secreting tumour.^[3]

Treatment

Treatment depends on severity. In the 29-patient series, mild cases were treated with topical benzoyl peroxide, erythromycin or retinoids. Moderate cases received oral paediatric erythromycin at 125 mg twice daily plus topical therapy, and some patients with antibiotic-resistant bacteria were given trimethoprim.^[1:2]

Tetracycline antibiotics are avoided in young children because they can stain developing teeth.^[3:2] For nodules and cysts, Gencler and colleagues add intralesional triamcinolone, and they list isotretinoin for severe or scarring disease.^[2:2]

Oral isotretinoin is off-label in infants. Santos and colleagues report doses in the published literature of 0.2 to 2.0 mg/kg/day over five to 14 months of treatment, and describe recent reports of both clinical improvement in refractory cases and safe use in infants.^[4:1] The evidence base for this use consists of case reports rather than controlled trials.

Prognosis

Outcomes vary between sources. In the 29-patient series, acne took six to 40 months to clear, with a median of 18 months, and 17% of patients were left with scarring.^[1:1] Gencler and colleagues report that lesions disappear after one to two years in some patients, but usually persist, with most recovering after age four to five.^[2:1] The difference may reflect which patients each source studied; a specialist clinic series is likely to include more persistent cases. The sources do not say.

DermNet states that severe infantile acne may leave permanent scars and that people who have it tend to develop troublesome acne at puberty.^[3:2] The sources reviewed here do not give figures for how often infantile acne is followed by severe adolescent acne.