Neonatal and Infantile Acne Vulgaris: An Update

Acne vulgaris typically is associated with adolescence and young adulthood; however, it also can affect neonates, infants, and small children.¹ Acne neonatorum occurs in up to 20% of newborns. The clinical importance of neonatal acne lies in its differentiation from infectious diseases, the exclusion of virilization as its underlying cause, and the possible implication of severe acne in adolescence.² Neonatal acne also must be distinguished from acne that is induced by application of topical oils and ointments (acne venenata) and from acneform eruptions induced by acnegenic maternal medications such as hydantoin (fetal hydantoin syndrome) and lithium.³

Neonatal Acne (Acne Neonatorum)

Clinical Presentation

Neonatal acne (acne neonatorum) typically presents as small closed comedones on the forehead, nose, and cheeks (Figure 1).⁴ Accompanying sebaceous hyperplasia often is noted.⁵ Less frequently, open comedones, inflammatory papules, and pustules may develop.⁶ Neonatal acne may be evident at birth or appear during the first 4 weeks of life⁷ and is more commonly seen in boys.⁸

Figure 1. Neonatal acne on the cheeks with pustules.

Etiology

Several factors may be pivotal in the etiology of neonatal acne, including increased sebum excretion, stimulation of the sebaceous glands by maternal or neonatal androgens,⁴ and colonization of sebaceous glands by Malassezia species.² Increased sebum excretion occurs during the neonatal period due to enlarged sebaceous glands,² which may result from the substantial production of β-hydroxysteroids from the relatively large adrenal glands.^9,10 After 6 months of age, the size of the sebaceous glands and the sebum excretion rate decrease.^9,10

Both maternal and neonatal androgens have been implicated in the stimulation of sebaceous glands in neonatal acne.² The neonatal adrenal gland produces high levels of dehydroepiandrosterone,² which stimulate sebaceous glands until around 1 year of age when dehydroepiandrosterone levels drop off as a consequence of involution of the neonatal adrenal gland.¹¹ Testicular androgens provide additional stimulation to the sebaceous glands, which may explain why neonatal acne is more common in boys.¹ Neonatal acne may be an inflammatory response to Malassezia species; however, Malassezia was not isolated in a series of patients,¹² suggesting that neonatal acne is an early presentation of comedonal acne and not a response to Malassezia.^2,12

Differential Diagnosis

There are a number of acneform eruptions that should be considered in the differential diagnosis,³ including bacterial folliculitis, secondary syphilis,¹³ herpes simplex virus and varicella zoster virus,¹⁴ and skin colonization by fungi of Malassezia species.¹⁵ Other neonatal eruptions such as erythema toxicum neonatorum,¹⁶ transient neonatal pustular melanosis, and milia and pustular miliaria, as well as a drug eruption associated with hydantoin, lithium, or halogens should be considered.¹⁷ The relationship between neonatal acne and neonatal cephalic pustulosis, which is characterized by papules and pustules without comedones, is controversial; some consider them to be 2 different entities,¹⁴ while others do not.¹⁸

Treatment

Guardians should be reassured that neonatal acne is mild, self-limited, and generally resolves spontaneously without scarring in approximately 1 to 3 months.^1,2 In most cases, no treatment is needed.¹⁹ If necessary, comedones may be treated with azelaic acid cream 20% or tretinoin cream 0.025% to 0.05%.^1,2 For inflammatory lesions, erythromycin solution 2% and benzoyl peroxide gel 2.5% may be used.^1,20 Severe or recalcitrant disease warrants a workup for congenital adrenal hyperplasia, a virilizing tumor, or underlying endocrinopathy.¹⁹

Infantile Acne Vulgaris

Clinical Presentation

Infantile acne vulgaris shares similarities with neonatal acne^21,22 in that they both affect the face, predominantly the cheeks, and have a male predominance (Figure 2).^1,10 However, by definition, onset of infantile acne typically occurs later than acne neonatorum, usually at 3 to 6 months of age.^1,4 Lesions are more pleomorphic and inflammatory than in neonatal acne. In addition to closed and open comedones, infantile acne may be first evident with papules, pustules, severe nodules, and cysts with scarring potential (Figure 3).^1,2,5 Accordingly, treatment may be required. Most cases of infantile acne resolve by 4 or 5 years of age, but some remain active into puberty.¹ Patients with a history of infantile acne have an increased incidence of acne vulgaris during adolescence compared to their peers, with greater severity and enhanced risk for scarring.^4,23

Figure 2. Infant with facial acne. Reprinted with permission from Cutis. 1993;52:16. ©1993, Frontline Medical Communications Inc.22

Figure 3. Infantile acne is more pleomorphic and inflamed than neonatal acne.

Etiology

The etiology of infantile acne remains unclear.² Similar to neonatal acne, infantile acne may be a result of elevated androgens produced by the fetal adrenal glands as well as by the testes in males.¹¹ For example, a child with infantile acne had elevated luteinizing hormone, follicle-stimulating hormone, and testosterone levels.²⁴ Therefore, hyperandrogenism should be considered as an etiology. Other causes also have been suggested. Rarely, an adrenocortical tumor may be associated with persistent infantile acne with signs of virilization and rapid development.²⁵Malassezia was implicated in infantile acne in a 6-month-old infant who was successfully treated with ketoconazole cream 2%.²⁶