Scalp psoriasis differes from seborrhoeic dermatitis in that the scale is thicker and more extensive and itch is not as prominent a feature. Check for psoriasis elsewhere on the elbows and knees.
Treatment centres around removing the scale with a keratolytic such as 6% salicylic acid in emulsifying ointment applied overnight for 3 nights followed by a steroid lotion such as Novasone or a combination product such as Daivobet gel. Avoid scratching as this invokes the Koebner reaction which makes the scaling worse. Tar shampoos help delay recurrences.