Erythema nodosum leprosum
| Erythema nodosum | |
|---|---|
 |
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| Erythema nodosum in a person who had recently had | |
| Classification and external resources | |
| Specialty | Dermatology, rheumatology |
| ICD-10 | L52 |
| ICD-9-CM | 695.2, 017.1 |
| DiseasesDB | 4462 |
| MedlinePlus | 000881 |
| eMedicine | derm/138 |
| MeSH | D004893 |
Erythema nodosum (EN) is an inflammatory condition characterised by inflammation of the fat cells under the skin, resulting in tender red nodules or lumps that are usually seen on both shins. It can be caused by a variety of conditions, and typically resolves spontaneously within 30 days. It is common in young people between 12–20 years of age.
The first sign of erythema nodosum is often flu-like symptoms. It may involve a pyrexia, weakness and arthralgia.
It is characterized by the appearance of dermo-hypodermic rounded nodules which may be bright red or purplish, bilaterally symmetrical, located on the extensor surface of the legs. They are movable relative to the deep plane and skin. They generally disappear in 1–6 weeks without sequelae.
Erythema nodosum is characterised by red nodules that are tender and warm. Nodules occur under the skin, classically in front of the shins. Nodules may occur anywhere there is fat under the skin, including the thighs, arms, trunk, face, and neck.
Erythema nodosum may occur concurrently with fever, malaise, and joint pain and inflammation. Nodules vary from 1–10 cm in diameter, and may coalesce to form large areas of hardened skin.
As the nodules age, they become bluish purple, brownish, yellowish, and finally green, similar to the color changes that occur in a resolving bruise. The nodules usually subside over a period of 2–6 weeks without ulceration or scarring.
Less common variants of erythema nodosum include:
EN is associated with a wide variety of conditions, including:
In about 30–50% of cases, the cause of EN is unknown.
EN may also be due to excessive antibody production in lepromatous leprosy leading to deposition of immune complexes.
There is an association with the HLA-B27 histocompatibility antigen, which is present in 65% of patients with erythema nodosum.
A useful mnemonic for causes is SORE SHINS (Streptococci, OCP, Rickettsia, Eponymous (Behçet), Sulfonamides, Hansen's Disease (Leprosy), IBD, NHL, Sarcoidosis.
Erythema nodosum is probably a delayed hypersensitivity reaction to a variety of antigens. Although circulating immune complexes have been demonstrated in patients with inflammatory bowel disease, they have not been found in idiopathic or uncomplicated cases.
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