Pityriasis and dandruff are the same problem, the skin regenerates naturally and gradually from the inside to the outside of the epidermis by a natural process and shows a scale (cornified dead cells) are constantly replaced.
We refer to the normal process of cell regeneration. The excessive flaking or dandruff causes pityriasis. Pityriasis esteatoide or oily dandruff flakes are set to see attached to the scalp. The sebum is matted and even sometimes grouped into scabs.