In some cases, the localized purple coloration is due to bruising of the skin after trauma, which can lead to a distinct purple coloration of the skin. There are also patients who have purple skin due to severe cold. Many patients have purple or bruised skin after cold, which can be slowly relieved by itself after warmth. In other cases, the condition can be caused by shock or severe anemia. In other cases, the purple coloring of the body, such as in the lower extremities, may be due to poor local blood flow, such as occlusive atherosclerosis, which can lead to purple coloring of the extremities. However, other patients with purple limbs are suffering from Raynaud’s phenomenon, which is often closely related to various connective tissue diseases in clinical practice, such as rheumatoid arthritis, lupus erythematosus, dermatomyositis, scleroderma, etc.