Erythema nodosum is a limited vasculitis skin disease of deep dermis or subcutaneous tissue caused by some reasons.
1.Cause: Erythema nodosum is caused by many and complicated factors, and it is generally believed that it is closely related to infection, drugs, systemic or visceral diseases, etc., but still about half of them cannot be found.
Infection is the most common cause of this disease. Some patients have a history of elevated anti-O values and upper respiratory tract infections before the disease, so the role of streptococcal infections is highly valued. In addition, the disease can also be caused by fungi or tuberculosis.
Certain drugs such as birth control pills, bromides, iodine, sulfonamides, etc. can cause erythema nodosum.
Systemic or organ diseases such as systemic lupus erythematosus, Behcet’s disease, ulcerative colitis, leukemia and other malignant neoplasms can often be accompanied by erythema nodosum-like lesions.
2.Pathogenesis: The pathogenesis of erythema nodosum can be regarded as a kind of allergic reaction, which may be recorded in the category of delayed allergic reaction, but some of them are also related to type III allergic reaction.
3.Clinical manifestation
Erythema nodosum is common in young adults, especially in females, and it is usually easy to develop in spring and autumn. There is a history of upper respiratory tract infection 1-2 weeks before the onset of the disease. Patients often have prodromal symptoms such as malaise, fatigue, low fever, joint and muscle aches and pains.
Erythema nodosum can have acute onset or insidious onset. The lesions usually appear on the extensor side of the lower legs, and sometimes on the lower thighs and buttocks, but the upper extremities and facial areas are usually not affected.
The rash appears as subcutaneous nodules, the surface skin of which is bright red at first and gradually turns dark red or light purplish red after about 2 weeks, the number is variable, and the size is about 1-4 cm in diameter, often in clusters or in scattered symmetrical distribution. The nodules never break down, but if the adjacent damage fuses with each other, they can form larger hard masses. Thus, compression of local blood vessels can easily occur, resulting in obstruction of venous return. This can cause edema in the lower leg. The nodules of the lesion are painful to the touch, and the pain to the touch is also obvious. The course of the disease must be 3-6 weeks, the nodules can gradually subside, but repeatedly see recurrence. Sometimes, new subcutaneous nodules can be seen in batches and stages, resulting in prolonged and long-lasting illness.
4.Auxiliary examination
(1) Some patients may show accelerated blood sedimentation and elevated anti-“O” value; if caused by tuberculosis bacteria, the tuberculin test is strongly positive.
(2) Pathology: The histopathology of the disease is inflammatory lesions in the dermis and subcutaneous tissue. The main manifestation is vasculitis, within the damage, especially the inflammatory infiltration and endothelial cell proliferation in the walls of the larger small veins, but the lumen is open, no occlusion, and no thrombosis. There is inflammatory cell infiltration around the vessels, predominantly neutrophils in the early stage, but lymphocytes in the late stage.
5.Diagnosis and differentiation
Based on the above features of clinical manifestations, the diagnosis can generally be made.
The disease must be distinguished from erythema rigidum. The latter lesion is usually found on the flexor side of the calf, which can break down and leave scars after healing. The conscious pain is mild. The course of the disease is chronic. Histopathological changes are tuberculous, and the inflammatory infiltration, thickening, lumen occlusion and thrombosis of the vessel wall at the lesion site.
6.Treatment.
(1) search for and remove the suspected cause of the disease
(2) Bed rest, elevation of the affected limb or minimization of activity during the acute period.
3) Internal therapy
*Antibiotics: If there is upper respiratory tract infection or fever is significant, antibiotics or sulfonamide preparations can be administered. If tuberculosis is identified as the cause, anti-tuberculosis treatment is feasible.
*Non-steroidal anti-inflammatory drugs: Especially suitable for those with unknown causes, commonly used for internal use such as anti-inflammatory pain and aspirin can be effective.
*Potassium iodide combination: 5-10 ml each time, taken orally 3 times a day, can be effective in some patients.
*Corticosteroids: This drug should be used with caution in patients other than those with severe disease caused by drugs.
(4) Topical therapy: 10% ichthyolite ointment can be used topically, which has anti-inflammatory function.
(5) physical therapy: audio current magnetic therapy can be used as appropriate, and the effect is quite good for some patients.
(6) Chinese medicine treatment: Chinese medicine to activate blood circulation and eliminate blood stasis treatment, can use the peach and red four things soup or the formula and two Chen Tang formula as appropriate, plus or minus treatment.