In daily medical work, we often encounter some patients who think that dotted spots are all freckles, some of them leave them alone and let them develop, while some of them take the wrong treatment methods, resulting in unfortunate consequences. The so-called freckle is a kind of yellowish brown or dark brown dotted spots commonly found on the face. Some of them have hereditary tendency. Most of them appear around 3-5 years old, more in women, and increase with age. These brown spots usually appear on the face (especially on the nose and cheeks), neck and shoulders, but they can also appear on the back of the hands and feet. There are usually no uncomfortable symptoms such as pain and itching. They are usually worse in summer and can often be reduced in winter. However, some punctate discoloration may be pigmented dry dermatosis and can be easily confused with freckles, especially in mild cases. The disease also develops soon after birth, and the discoloration deepens after sun exposure, which can lead to erythema and heterochromatosis-like skin changes, and the rash does not fade in winter, with a darker skin tone. The disease is prolonged, gradually worsens, and eventually may lead to cancer and form squamous cell carcinoma or basal cell carcinoma. Another disease that is often confused is hyperpigmentation, which is also a skin disease with a family tendency to run in families. It begins shortly after birth with freckle-like spots on the forehead, back of the hands and back of the feet. If preventive measures are not taken in time, the disease will spread to the extremities and trunk. If the family genetic characteristics are obvious, genetic diagnosis can be made through molecular genetics techniques, and prenatal diagnosis can also be used to prevent the transmission of the disease to the next generation.