• seborrheic dermatitis is most common in infants within the first two months of birth
• appears as  erythematous, greasy yellow scales most commonly on the scalp (cradle cap), and may also occur on the face
• most cases resolve spontaneously within weeks to months, but severe cases may be treated with 1% hydrocortisone cream, sahmpooing with selenium sulfide, and using an emollient to remove scales
• in extreme cases, consider hte possibility of Langerhans cell histicytosis, especially if atrophy, ulceration, or purpura are also present
• rarely occurs in children between 1 and 12 as they do not have active sebaceous glands, but will appear as dandruff in adolesecents
   

References

Pediatrics Board Review Core Curriculum, 1st edition

MedStudy