First of all, we need to know that erythema nodosum is a relatively common disease in female patients. It is frequently encountered in spring and autumn. Let's understand the pathogenic factors and clinical symptoms of erythema nodosum.
Erythema nodosum is a kind of skin allergy caused by many reasons. The real pathogenesis is not clear. Some people think that it is one of them, but immunofluorescence technology can not find the deposition of immune complex in the necrotic area.
Some people think that the disease is a delayed reaction of blood vessels to microorganisms or other antigens.
2. The main pathological changes occurred in subcutaneous fat layer and subdermal fat lobular septum. In the early stage of acute inflammatory reaction, neutrophil infiltration was mainly accompanied by a small amount of lymphocytes, eosinophils and a small amount of red blood cells extravasation.
Clinical manifestations: it is a common nodular skin disease caused by vasculitis. It is common in red or purple red painful inflammatory nodules on the extension side of the leg. It is common in young women. The course of disease is limited and easy to relapse. Before the onset of the disease, there was a history of infection or medication, and the skin lesions suddenly occurred. The lesions were bilateral symmetrical subcutaneous nodules, ranging in size from broad bean to walnut, with the number of 10 or more, conscious pain or tenderness, moderate hardness.
In the early stage, the skin color was light red, the surface was smooth and slightly uplifted. After a few days, the skin color turned dark red or cyan red, and the surface became flat. After 3-4 weeks, the nodule gradually subsided, leaving temporary pigmentation and no ulcer.
Skin lesions often occur in front of the tibia, also can be seen in the thigh, arm extension side and neck, rarely in the face. Chronic: different from acute features: often occurs in elderly women, skin lesions for unilateral, if bilateral, then asymmetric, except joint pain, without other systemic symptoms. The nodule is painless and softer than acute.