Scaling is one of the most common secondary skin lesions in dermatological diseases. It is produced by the epidermis of the skin and is mostly seen in the red patches and macules of superficial inflammatory skin diseases. While in larger, deeper in, located in the deep dermis, subcutaneous tissue and fat layer of the nodules, cysts J membrane inflammation and tumors, because of its deeper site, far from the epidermis and superficial dermis, so scaling is less common. In the normal epidermis keratinocytes are keratin-forming cells, generally consisting of four layers: the lowermost layer is the basal cell layer, the uppermost layer is the spiny layer, the granular layer, and the outermost one is the stratum corneum. In the palm of the hand and foot, where the stratum corneum is thicker, there is a transparent layer between the stratum granulosum and the stratum corneum. Under normal circumstances, the growth and metabolic cycle of epidermal keratinocytes is 12 d. In the case of inflammatory stimulation, the growth and proliferation of keratinocytes is accelerated, such as psoriasis can be shortened to 5 d. Therefore, the law of keratin formation is disturbed, and keratin formation is disrupted, so that incomplete keratinization occurs, and many keratinocytes that are not fully keratinized and matured enter the stratum corneum with their nuclei. So that the keratin is not dense and hard, but becomes loose and easy to fall off to form scales. Because of the laxity, there are gaps for light transmission and refraction, so the scales are often white. Scales have different forms and characteristics in different skin diseases, so they have their diagnostic value. Not all scales are produced by inflammatory stimulation of the epidermis, and some of them are non-inflammatory, such as the scales of congenital hereditary ichthyosis are non-inflammatory; squamous follicular keratosis is also non-inflammatory. Therefore, scaly genera can be divided into two categories: inflammatory scales and non-inflammatory scales.