The process of keratin formation in the stratum corneum is called keratinization, which is the process of converting cellular proteins into keratin with completely different physical and chemical properties. Patients need to do the following tests: 1, skin lesions Skin lesions are skin damage caused by external pathogenic microbial infections or internal lesions. The shape and arrangement of skin damage in most skin diseases have a certain pattern. A clear understanding of the shape and arrangement of skin lesions can help in the diagnosis of skin diseases and the observation of the progress and prognosis of skin diseases. 2.Cellular histochemical staining Immunocytochemical staining is the use of known antibodies and cellular antigen specific combination of properties, through the chemical reaction to make the display agent labeled on the antibody to show a certain color, and with the help of microscopy, fluorescence microscopy or electron microscopy for observation, in order to achieve the purpose of quantitative, localized analysis of chemical components in the tissue, cell structure. 3.Immunopathological examination Immunopathological examination is a kind of examination using the principle of immunology, such as: skin patch test, ringworm test, allergen screening, etc.