There is no such thing as a yellow spot on the leg is a sign of what disease, patients with yellow patches on the leg, may be caused by age spots, subcutaneous hemorrhage and so on. 1. Age spots: age spots are a kind of degenerative skin changes of the elderly, manifested as scattered pigmented patches of varying sizes, flat or slightly higher than the skin surface, with smooth surface and brownish color, and the yellow spots on the patient’s legs may be age spots. 2. Subcutaneous hemorrhage: due to local external force or chronic exertion or strain, which injures the local capillaries, patients may have subcutaneous hemorrhage, which is not absorbed in time, and can gradually form bruises, which are manifested as subcutaneous bruises in appearance, so that the patients may have tawny plaques on their legs. It is recommended that patients with yellowish-yellow plaques on the legs should consult a doctor in a timely manner to assess their condition and follow the doctor’s instructions for treatment.