Erythema nodosum is an inflammation of the subcutaneous fat. It is not a disease but a reaction pattern to various immunological reactions caused by different viral, bacterial, fungal infections, drugs, malignant disorders and other causes.
Erythema nodosum is commonly seen in women of age 20 to 40 but may occur at any age. Erythema nodosum starts with a sudden onset of symmetric, tender and erythematous nodules or raised plaque on the legs or forearm, most often seen on shin of the legs. After few days the nodules turn purple or red color than to green or yellowish color. One may have fever, headache, joint pain, abdominal pain, vomiting and diarrhea. The nodules may be so tender that walking may be difficult. Lesions usually resolve without scarring within 5-6 weeks. There is no ulceration seen and the lesion heals without scarring or atrophy. These lesions usually last 3-6 weeks and resolves, however, EN may recur frequently if the causative agent is not removed or treated.
Although erythema nodosum results from wide variety of etiologic agents, streptococcal infections are considered as most frequent causative factor in children. In contrast, adult erythema nodosum is most commonly associated with drugs, sarcoidosis, and inflammatory bowel disease to a large number of inciting factors. Below are several etiological factors for Erythema Nodosum
Atypical mycobacterial infections
Corynebacterium diphtheriae infections
Mycoplasma pneumoniae infections
Erythema Nodosum Pictures
Hepatitis B vaccine
Post-radiotherapy for pelvic carcinoma
Chronic active hepatitis
Immunoglobulin A nephropathy
Treatment of Erythema Nodosum
As several agents may cause erythema nodosum, eliminating these causative factors is the main aim of the treatment. Besides treating causative factors, bed rest is also very important part of treatment. Pain killers like aspirin, indomethacin or ibuprofen are helpful for those experiencing pain. In severe cases systemic corticosteroids may be given by your doctor or are not generally required for mild cases.
Fitzpatrick’s Dermatology in General Medicine, 7th Edition