Understanding Seborrheic Dermatitis in Babies - Cradle Cap

Author: Wang Xue Beijing Children's Hospital, Capital Medical University

Reviewer: Ma Lin, Chief Physician, Beijing Children's Hospital, Capital Medical University

What is cradle cap?

Cradle cap is a yellow, greasy crust that appears on the baby's scalp and face when the baby is just born or soon after birth. It feels rough and firm when touched by hand. It is most common on the scalp, forehead, behind the ears, eyebrows, cheeks, nasolabial grooves, top of the head and fontanelle.

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Is cradle cap the legendary eczema?

For mothers who have just given birth, eczema may be a word that appears very frequently. So, is the cradle cap mentioned by the elderly the baby's eczema?

The answer is no. The scientific name of cradle cap is seborrheic dermatitis. When you hear seborrheic dermatitis, you may feel familiar with it. It is characterized by excessive oiliness on the scalp and a lot of dandruff, which usually appears after puberty. In fact, there are two peak age groups for seborrheic dermatitis, and puberty is only one of them.

Cradle cap is another peak period of seborrheic dermatitis that occurs in infancy. It usually occurs most frequently in babies between 1 week and 3 months old, and decreases significantly by 1 year old.

How is cradle cap formed?

1. The early development of cradle cap in infancy may be related to hormone-dependent sebum secretion, which decreases in childhood and increases again in adolescence and adulthood.

2. Current research shows that its appearance is inseparable from Malassezia, which was formerly known as Pityrosporum, a fungus. Everyone is familiar with fungi, from mushrooms to dermatophytes that can cause tinea pedis or onychomycosis. Malassezia can live in peace with us most of the time and can exist on normal skin. They like to settle in oily parts of the body and live on the oil there, processing the triglycerides in the original sebum into unsaturated fatty acids such as oleic acid and arachidonic acid. Their role also lays a hidden danger for the occurrence of seborrheic dermatitis, because these unsaturated fatty acids can damage our skin and cause inflammation of the skin. So, do children with severe milk crust have more Malassezia on their skin? Studies have shown that the occurrence of seborrheic dermatitis is related to the susceptibility of different infants, and has nothing to do with the amount of bacteria, which means that children with milk crust have a certain genetic background.

3. Seborrheic dermatitis occurs in oily areas because the sebaceous glands here are active. Current studies have found that the activity of sebaceous glands is highly correlated with seborrheic dermatitis.

4. In addition to Malassezia, there are other microorganisms such as bacteria on the skin surface. Therefore, some studies speculate that the occurrence of seborrheic dermatitis may be related to the imbalance of the skin's microecological flora.

5. The recent accurate diagnosis of dominant and recessive seborrheic dermatitis has further confirmed the role of genetic factors in its pathogenesis.

How to deal with milk crust

1. Babies with small scabs, thin scabs, and non-red skin under and around the scabs can be classified as having a mild case. Use regular baby shampoo or baby shampoo and conditioner combination to wash your hair once a day for a week to soften and remove the scabs.

2. For babies with thick scabs covering a wide area but no obvious redness on the local skin, the condition can be classified as moderate. You can apply lotion on the scalp or face for a few hours or apply it before going to bed and wait overnight. Then use a silicone comb to gently remove the scalp scabs and wash them with ordinary baby shampoo.

3. Babies with redness under or around the scab, with or without itching, can be classified as severe cases. Antifungal shampoos such as ketoconazole can be used to reduce the colonization of Malassezia and improve erythema. Tea tree oil has an antibacterial effect on Malassezia and can also be used as a shampoo. Ointments with antifungal effects, such as creams containing miconazole or ketoconazole, can be used externally. In addition, topical ointments containing hormones can improve the inflammatory state of erythema and itching. You can choose triamcinolone acetonide econazole cream or desonide cream for external use for 7 to 10 days.

What diseases need to be identified when infantile seborrheic dermatitis occurs on the head and face?

1. Infant eczema often appears on the head, face and chest during infancy, and sometimes the limbs are also affected. It manifests as erythema with blisters, desquamation and scabs on the surface, but compared with seborrheic dermatitis, infant eczema appears later, often after 3 months of age, and the skin lesions have no clear boundaries. The baby will rub his face when leaning on the caregiver, or scratch with his little hands, which proves that the itching of infant eczema is very obvious and may even affect sleep. Such babies often have a family history of diseases such as eczema, allergic rhinitis and even asthma.

2. Psoriasis, commonly known as "psoriasis", is very rare in infancy. In addition to thick white scales, yellow scabs may appear, but the skin under the scales or scabs is red, and most people have a family history of psoriasis. Its diagnosis and treatment depends on professional physicians, so if you have any doubts, you need to seek medical attention actively.

3. Other rare diseases that need to be identified include Langerhans cell histiocytosis, which can cause seborrheic dermatitis or diaper dermatitis, and is ineffective with conventional treatments. It often causes ulceration and erosion. In addition, there is tinea capitis, which is also caused by fungi. This fungus is different from Malassezia and is a pathogenic fungus. Tinea capitis usually occurs when it is transmitted from an infectious source through a certain transmission route. If you have any doubts, you need to see a doctor for a complete examination.