Ichthyosis is a group of skin diseases with abnormal skin keratinization and scaling as the main clinical manifestation. Patients present with keratinized skin scales that resemble fish scales, with a large amount of flaking one by one, hence the name ichthyosis. Ichthyosis is not a single disease, but a large group of diseases, and there may be dozens of subtypes, which vary greatly from one subtype to another. Ichthyosis is the most common group of hereditary diseases in dermatology, and the incidence of different types varies, with the most common type of ichthyosis, the incidence of which may be as high as 5%-10% in China. There are different types of ichthyosis, the majority of which can show clinical symptoms at birth or shortly after birth, with immediate onset; the onset of common ichthyosis is a little later, and can occur at the age of two or three. There is another type called acquired ichthyosis, which develops later, usually in adulthood, triggered by a specific event. For example, acquired ichthyosis occurs after taking immunosuppressive drugs such as cyclophosphamide, or after a combination of diseases such as Hodgkin’s lymphoma. The severity of ichthyosis varies greatly from one type of ichthyosis to another. Although the appearance of ichthyosis patients is not very good, daily contact is not contagious, so please do not worry about the infection problem and do not discriminate against ichthyosis patients. If we find the factors for the development of acquired ichthyosis, such as the combination of Hodgkin’s lymphoma, then the lymphoma will be cured and the ichthyosis will be cured; if the patient develops the disease because of taking some immunosuppressive drugs, then the disease can be reversed naturally after stopping the drugs. However, more patients actually have hereditary ichthyosis, where there is a genetic defect in the patient’s body. The current technology cannot change the genes in the body safely, effectively and cheaply, so most hereditary ichthyosis can only be controlled but not effectively cured.