The appearance of reticular redness on the thighs may be caused by diseases such as capillary dilatation and spider nevus. 1. Capillary Dilatation Disorder: Typical symptoms include the appearance of various shapes of red spots on the skin, such as dots, spots, and asterisks, reticulation, filaments, etc. The cause of the disease is more complex, and it may be related to immune system disorders, the environment, physics, genetics, hormones and other factors. 2. Spider nevus: mainly manifested as a network of small blood vessels radiating outward, in the shape of a spider’s foot, the network of blood vessels radiating outward may disappear after pressing the center. Its etiology may be related to sex hormone metabolic changes, impaired liver function, Cushing’s syndrome and Raynaud’s disease. The appearance of reticular redness on the thighs may also be caused by other reasons, and it is recommended that the patient consult a doctor for examination to clarify the cause of the disease and standardize the treatment under the guidance of the doctor.