Erythema nodosum is a nodular, erythematous skin eruption that is characterized by sudden onset of red, painful, firm nodules and is commonly found on the extensor aspects of the lower legs. It is usually acute in nature; however, chronic or recurrent erythema nodosum may occur rarely. Erythema nodosum is an acute or recurrent hypersensitivity reaction and is mainly found in female population, resulting from exposure to various antigens; however, the pathogenesis is not fully understood. These painful nodules can stay inflamed for as long as period of three to six weeks, and then shrink and resolve on its own, leaving a bruised appearance. After it is gone, it may leave only a temporary bruised appearance or a chronic indentation in the skin.
Erythema nodosum may occur as an isolated condition or in association with other medical conditions. Conditions that are associated with erythema nodosum include: idiopathic cause, medications (sulfa-related drugs, birth control pills, penicillins, sulphonamides, bromides, iodides, tumor necrosis factor-alpha inhibitor and estrogens), bacterial infection (streptococcal infections-most common, tuberculosis, leprosy, salmonella, campylobacter gastroenteritis, mycoplasma pneumonia, Cat scratch disease, leptospirosis, brucellosis, psittacosis, chlamydia trachomatous, lymphogranuloma venereum), viral (Infectious mononucleosis, Hepatitis B, Hepatitis C, Human immunodeficiency virus, herpes simplex, epstein-barr virus) fungal (coccidioidomycosis, histoplasmosis, blastomycosis), parasitic (amebiasis, giardiasis), malignancy (leukemia, lymphoma, occult malignancies),inflammatory bowel disease (Crohn’s disease, Ulcerative colitis), miscellaneous (sarcoidosis, pregnancy
Whipple disease, Behcet disease)
Typically the skin eruptions are marked by fever, joint, and sometimes abdominal pain. Very often it is accompanied with nasopharyngeal infection and malaise. Inflammed and tender red nodules appear on the extended faces of the legs and knees, and sometimes thighs and forearms. These nodules are small, sometimes three to six nodules in number, many times occur bilaterally, and roughly symmetrical in nature. They resolve spontaneously in almost ten days, leaving a bruised blue appearance and completely disappear without sequelae. It never involves necrosis, ulceration, or scarring. However, in another pattern known as chronic erythema nodosum, the nodules may last for many years and not resolve soon.
The diagnosis of is primarily clinical. However, a thorough case history looking out for tuberculous infection, fever, abdominal pain, respiratory problems should be taken with complete clinical examination and associated signs. The laboratory investigations like blood count, C-reactive protein, Mantoux text to rule out tuberculosis infection, X-ray chest, culture test, stool examination, and cutaneous biopsy may be carried out.
The physician will treat the underlying condition responsible. Simultaneously, direct treatment need to be given for the the inflamed skin arising due to the erythema nodosum. Erythema Nodosum Treatment in India, the treatments include anti-inflammatory drugs, corticosteroids, colchicine, analgesics to reduce inflammation and pain, are prescribed till the symptoms and signs improve. Personalised treatments may need to be given depending on the underlying condition and any associated diseases. Antibiotic therapy may be given in case of streptococcal infection.