Reddish-brown patches on the body may be caused by solar keratosis, sweat pore keratosis and other diseases, the patient should consult a doctor in a timely manner to clarify the cause of the disease after treatment. 1 solar keratosis: also known as senile keratosis, is long-term sun exposure or ionizing radiation caused by excessive keratinization of the epidermis, mostly in long-term exposure to the sun in elderly men, some patients will develop into squamous carcinoma, can use liquid nitrogen freezing, laser, and topical fluorouracil cream, etc. for treatment. 2. Keratosis pilaris: If the reddish-brown patches on the body have dike-like raised edges, it should be considered to be caused by keratosis pilaris, a kind of rare acquired or hereditary keratinization disorder, which can be treated with topical fluorouracil and retinoic acid, etc. All the above drugs should be prescribed by a doctor. All of the above medications should be used under medical supervision.