Seborrhoeic dermatitis is commonly seen in infants as cradle cap, appearing as scaly, greasy, yellow patches on the scalp or in the nappy area, usually clearing by the infant’s first birthday
In teens, seborrhoeic dermatitis is found in areas of oily skin; on the scalp, around the sides of the nose, in the eyebrows, on the torso and in axilla and groin.
It is due to an inflammatory response to Malassezia yeast.
Treatment consists emollients such as petroleum jelly (for infants), to loosen scale, anti-fungal creams or shampoos, topical corticosteroids or other topical nonsteroidals.
https://dontforgetthebubbles.com/cradle-cap/
https://dermnetnz.org/cme/dermatitis/seborrhoeic-dermatitis/