What is Cradle Cap?
Infantile seborrhea, or “cradle cap,” is a frequent concern for new parents. The first signs may appear as early as two weeks old, and 70 percent of infants have at least one episode by the age of three months. 10 percent of infants have recurrences, but, for most, it resolves by the first birthday. Seborrheic dermatitis is more common in boys, and it tends to flare during cooler, less humid months. This skin condition may reappear at the onset of puberty and throughout adulthood.
Infantile seborrhea affects areas of the skin with a high concentration of oil-producing sebaceous glands. Its exact cause is still unknown, but there are several hypotheses. Increased levels of post-birth maternal hormones are thought to trigger its onset. There also appears to be a genetic predisposition. Skin microbiome changes, excessive shedding of keratin cells, and epidermal irritation all contribute to its development. A specific group of fungi, Malassezia species, is associated with some cases of seborrheic dermatitis. By colonizing the skin, it prevents sebum degradation and absorption of lipids. Impaired T Helper cell activity further promotes Malassezia growth, creating an ideal environment for this condition to develop.
The classic signs of infantile seborrhea include clusters of oily papules covered by a yellow flakes of skin. The scalp, forehead, eyebrows, and periauricular areas are commonly affected. In contrast, neck, axillary, and inguinal skin folds are often moist and erythematous. In severe cases, pityriasis amiantacea lesions develop. This is characterized by thick, “asbestos-like” yellow plaques that form on the scalp. These plaques are larger than the typical seborrheic flakes, and firmly attach to the hair. Pityariasis amianacea can also be associated with psoriasis, atopic dermatitis, and tinea captus.
In children and adolescents, seborrheic dermatitis has a similar appearance, but occurs on different locations of the body. Along with the scalp and ears, it is commonly seen around the nose and on the chest. Unlike infantile seborrhea, itching is a prominent symptom. In addition, it may be associated with allergies and asthma.
In most cases, seborrheic dermatitis is diagnosed solely by the clinical findings. KOH tests of the skin flakes may be used to detect the presence of Malassezia species, and skin cultures can help rule out bacterial infections.
Other medical conditions may mimic infantile seborrhea, but indicate a more serious problem.
• Psoriasis. The rash of psoriasis is characterized by lesions with an erythematous base, covered with white or silver plaques. Scratching releases dry skin flakes, and causes the underlying skin to bleed. One percent of infants experience psoriasis, and it typically affects the face and diaper area.
• Langerhans Cell Hystiocytosis (LCH). When the bone marrow produces too many white blood cell histiocytes, they form granulomas throughout the body. Skin manifestations of LCH are red, scaly papules that form on the scalp and opposing skin areas (i.e. inner thighs). This condition affects one in 200,000 children each year, and onset occurs between the ages of one and three. LCH is a multi-system organ disease, characterized by fever, oral lesions, jaundice, difficulty breathing, and central nervous system involvement.
• Leiner Disease. A defect in the complement system causes this severe form of seborrheic dermatitis. A yellow, oily rash begins on the scalp and face, then progresses down the body. Unlike the more common type of infantile seborrhea, it is associated with recurrent diarrhea, frequent infections, and failure to thrive. Symptoms are present at birth, or develop within the first four weeks of life.
• Acrodermatitis Enteropathica (AE). Infants born with this rare disorder have an intestinal defect that prevents the absorption of zinc. It can also occur due to a maternal issue that lowers the zinc content of breastmilk. Without zinc, the skin develops vesicles and blisters that progress to a dry, scaly rash. In addition to skin findings, AE is associated with inflammation of the mucous membranes, alopecia totalis, and chronic diarrhea.
Atopic and contact dermatitis are commonly seen in infants, and must be distinguished from infantile seborrhea. Itching is an uncommon symptom in the latter.
In the majority of cases, seborrheic dermatitis in infants is benign, and treatment is unnecessary. However, many parents are quite distressed by it, and seek the advice of a healthcare professional. First-line treatment involves loosening the scalp flakes with an emollient, then gently brushing them away. Shampooing the scalp afterward reduces the flakes, and removes excess oil that can exacerbate this condition. A tear-free infant shampoo is typically recommended as the safety of some adult dandruff shampoos ingredients have not been evaluated in this age group.
When other areas of the body are affected, a short course of a low potency hydrocortisone cream may be recommended to reduce inflammation. Due to potential side effects, it should not be applied near the eyes, mouth, or genitals. Promiseb is a non-steroid cream that specifically treats seborrheic dermatitis. It may be prescribed, but its efficacy in clinical trials has been inconsistent.