What are the pathological causes of melasma?

The pathological causes of melasma mainly include: 1. Endocrine disorders: For example, during pregnancy or menstrual cycle disorders in women, changes in estrogen levels may lead to the formation of melasma. In addition, according to traditional Chinese medicine theory, imbalance of Yin and Yang such as liver Qi stagnation, spleen and stomach weakness, and kidney Yang deficiency may also affect the circulation of blood and Qi, leading to facial blood stasis and the formation of melasma. 2. Ultraviolet radiation: Prolonged exposure to ultraviolet light stimulates melanocytes in the skin, resulting in excessive pigment deposition. This is an important factor in the development and worsening of melasma. 3. Genetic factors: Melasma has a certain hereditary tendency, and individuals with a family history are more susceptible to developing the condition. 4. Medication factors: Long-term use of oral contraceptives or hormone-containing medications may induce or exacerbate melasma. 5. Disease factors: Conditions such as hypopituitarism, chronic gastrointestinal diseases, and chronic liver disease may also be associated with the occurrence of melasma.