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Disease Profile

Erythema nodosum, idiopathic

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


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Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Idiopathic erythema nodosum; Erythema nodosum of unknown etiology


Skin Diseases


Erythema nodosum (EN) is a skin condition in which red bumps (nodules) form on the shins. Less commonly, the nodules form on other areas of the body such as the thighs and forearms.[1][2] The lesions begin as firm, hot, red, painful lumps and progress to a purplish color.[1] EN is a type of inflammatory disorder affecting the layer of fat under the skin (panniculitis).[2][3] Other symptoms that may accompany the skin findings include the following: fever, a general feeling of being ill. joint aches, and swelling of the affected area.[1] In many cases, EN is presumed to be a delayed reaction to antigens associated with various infections, drugs, and certain systemic diseases.[3] In some cases, however, EN has no identifiable cause (idiopathic); in these cases, clinical follow-up is needed to rule out certain conditions including inflammatory bowel disease, sarcoidosis, lymphoma, and Behcet's disease.[3] Treatment may include rest, nonsteroidal anti-inflammatory drugs (NSAIDS), steroids, hot or cold compresses, potassium iodide solution, and supportive bandages or compression stockings.[1][2] Symptoms usually resolve within six weeks, but EN may become a chronic disorder lasting for months and, occasionally, for years.[1][2] Approximately 30% cases of idiopathic EN may last more than 6 months.[4]


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    Learn more

    These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

    In-Depth Information

    • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
    • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
    • PubMed is a searchable database of medical literature and lists journal articles that discuss Erythema nodosum, idiopathic. Click on the link to view a sample search on this topic.


      1. Erythema nodosum. MedlinePlus. October 18, 2013; https://www.nlm.nih.gov/medlineplus/ency/article/000881.htm. Accessed 9/24/2015.
      2. Erythema nodosum. DermNet New Zealand Trust. August 1, 2015; https://www.dermnetnz.org/vascular/erythema-nodosum.html. Accessed 9/24/2015.
      3. Shojania, Kaveh. Erythema nodosum. UpToDate. November 27, 2013; https://www.uptodate.com/contents/erythema-nodosum. Accessed 9/24/2015.
      4. Hebel, Jeanette. Erythema Nodosum. Medscape Reference. April 13, 2015; https://emedicine.medscape.com/article/1081633-overview. Accessed 9/24/2015.