Bluish purple fingernails should be a sign of poor peripheral circulation and may be a sign of Raynaud’s syndrome. Diagnosis: In the vast majority of patients with Raynaud’s syndrome, the diagnosis can be made on the basis of a history of intermittent changes in the color of the skin on the extremities. However, it is best to observe the onset of symptoms, the nature, extent, degree and duration of the skin color change. The typical symptoms described above can be induced by immersing the patient’s hands or feet in cold water or exposing them to cold air. Differential diagnosis: attention should be paid to differentiate from other vascular dysfunction diseases characterized by skin color changes. I. Cyanosis of hands and feet is a vasospastic disease caused by vegetative nerve dysfunction. Mostly seen in young women, the skin of hands and feet is symmetrical uniform cyanosis. Cold can make the symptoms worse. Often accompanied by skin scratches or sweaty hands and feet and other phenomena of phytoneurological disorders. Its pathological changes are persistent spasm of small arteries and varicose capillaries and veins in the extremities, which need to be differentiated from Raynaud’s syndrome. Patients with hand and foot cyanosis do not have typical skin color changes, and the cyanosis is more extensive, involving the whole hand and foot, and even involving the whole limb. Cyanosis lasts for a long time. Cold can make the symptoms worse, but in a warm environment often can not make the symptoms immediately reduce, or disappear, emotional hormones and mental tension generally do not induce this disease. Second, reticular cyanosis is mostly for women, due to small artery spasm, capillary and venous atonic dilatation. The skin is persistent reticular or blotchy cyanosis. The lesions mostly occur in the lower limbs, occasionally can involve the upper limbs, trunk and face. The affected limbs are often accompanied by coldness, numbness, and sensory abnormalities. Cyanosis is evident in the cold or when the limb is drooping. In a warm environment or after elevating the affected limb, the mottling decreases or disappears. Clinically, it can be divided into three types: marble-like skin spots, idiopathic reticular erythema and symptomatic reticular erythema. Third, the etiology of erythematous limb pain leveling is still unclear. Pathologic changes are symmetrical, stigmata vasodilatation of the extremities. Mostly seen in young women. The onset of the disease is acute, both feet at the same time, and may occasionally involve both hands. Symmetrical paroxysmal severe burning pain. When the foot temperature exceeds the critical temperature (about 33 ~ 34 ℃), such as the foot in the warm bedding, the pain can be attacked, mostly burning-like, but also can be tingling or swelling pain. The pain can be induced by drooping, standing, or movement, and can be relieved by elevating the affected limb, resting, or exposing the foot outside the bedding. During the onset of symptoms, the skin color of the foot is flushed and congested, the skin temperature rises with sweating, and the dorsal and posterior tibial arterial pulsations increase. Based on the presenting features, it is easily similar to Raynaud’s syndrome. In a few cases, erythematous limb pain may be secondary to true erythrocytosis or diabetes mellitus. Diagnosis: In the vast majority of patients with Raynaud’s syndrome, the diagnosis can be made on the basis of a history of intermittent changes in the color of the skin of the extremities. However, it is best to visualize the onset of symptoms, the nature, extent, degree and duration of the skin color change. The typical symptoms described above can be induced by immersing the patient’s hands or feet in cold water or exposing them to cold air. In order to detect the related diseases that may be associated with the early detection, the history should focus on the history of systemic connective tissue diseases and arteriosclerosis, vasculitis and other vascular disorders, and the history of vascular trauma; the history of ergotamine, beta;-receptor blockers and contraceptives; and the history of occupational history of the long-term application of vibrating instruments. Physical examination should focus on signs suggestive of systemic connective tissue disease: e.g., thinning and tightening of the skin, capillary dilatation, rashes, dry lips and mouth; thickening of synovial membranes of the joints, exudate or other evidence suggestive of arthritis. Carefully observe the skin of the fingers for ulcers or hyperkeratotic areas of healed ulcers; note peripheral arterial pulsations; and also be alert and aware of the presence of carpal tunnel syndrome. Patients in whom no associated disease is found should be followed up over time.