Reticular cyanosis is a skin spasmosis, a skin manifestation of certain diseases, and some normal people also develop reticular cyanosis in cold environments. Gangrene is a specific morphologic change of black and dark green color due to secondary infection by spoilage bacteria and other factors after tissue necrosis. Both are seen together in the skin lesions of polyarteritis nodosa. Polyarteritis nodosa, also known as periarteritis nodosa and necrotizing arteritis, polyarteritis, etc., is a fatal disease. The clinical course of the disease is rapid and extensive, usually involving the systemic arterial system, with complex and variable clinical manifestations that vary according to the site or organ involved. The most common early manifestations are fever of unknown origin, hypertension, acute abdominal pain, glomerulonephritis, coronary artery insufficiency, peripheral neuropathy, and muscle and joint lesions. Nodular polyarteritis is clinically classified into systemic (systemic) and limited types according to the involvement of tissues and organs. The clinical manifestations are complex and varied because of the involvement of various tissues and organs, with atypical systemic symptoms being common in the early stages of the disease, but also a system or organ being the main manifestation. The skin type lesions are confined to the skin and are characterized by nodules, usually 0.5-25px in size, firm, single or multiple, arranged along superficial arteries or irregularly clustered near blood vessels, rosy, bright red or near normal skin color, free to push or adhere to the skin above it, with pressure pain, the center of the nodule can be necrotic and form ulcers, the edges are not Liu, often with reticulocutaneous bruises, pemphigus, blisters and Purpura, etc. The lesions may be polymorphic and generally have no systemic symptoms, or may be accompanied by hypothermia, arthralgia, myalgia and other discomforts. Benign process with intermittent attacks. Systemic type with acute or insidious onset, often with irregular fever, malaise, arthralgia, myalgia, decreased physical signs and other peripheral discomfort. 1, renal lesions are most common, there may be proteinuria, hematuria, a few presenting nephrotic syndrome manifestations, but the renal damage of the disease is vasculitis of the small renal arteries rather than glomerulonephritis, proteinuria as well as hematuria due to ischemia or infarction of the small renal arteries, etc. Intrarenal aneurysm rupture or due to infarction can appear severe renal colic and massive hematuria. Hypertension is more common and sometimes the only clinical manifestation. Hypertension aggravates renal damage, and uremia is one of the main causes of death in this disease. 2. Digestive system involvement varies according to the location of the lesion, with abdominal pain being the most common, and vomiting and blood in the stool. The rupture of small aneurysm may cause bleeding in the digestive tract or abdominal cavity, manifested as severe abdominal pain, signs of peritonitis, liver involvement may have jaundice, epigastric pain, elevated transaminases, and chronic active hepatitis in cases of combined hepatitis B virus infection. When the gallbladder and pancreas are involved, the symptoms of acute cholecystitis and acute pancreatitis may be manifested. 3, the cardiovascular system is also more often involved, in addition to renal hypertension can affect the heart, mainly due to coronary arteritis produce a angina pectoris, serious cases of myocardial infarction, heart failure, a variety of arrhythmias can appear, with supraventricular tachycardia is common, heart failure is also one of the main causes of death in this disease. Peripheral and central nerves can be involved in the nervous system. Peripheral neuropathy is common, with abnormal sensation in the distribution area, motor disorders, polyneuritis, polyneuropathy, etc. When the central nerve is involved, there may be dizziness and headache, and cerebral artery thrombosis or aneurysm rupture may cause hemiparesis, while spinal cord involvement is less common. The skin lesions are similar to those seen in the skin type, and some patients have Raynaud’s phenomenon. 6. Pulmonary vessels are rarely involved, and ocular symptoms account for about 10%. In other cases, such as the reproductive system, 80% of the autopsy material is involved in the testes and parametrium, but only about 20% of the patients have clinical manifestations. The course of the disease varies depending on the severity of the involved organs. In severe cases, the disease progresses rapidly, even to death. There are also cases in which remission and attacks alternate and last for many years before finally recovering.