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Erythema nodosum

Evidence: Unconfirmed

Names

Idiopathic erythema nodosum
Erythema nodosum of unknown etiology
EN

Description

Erythema nodosum is a condition that causes the fat layer just beneath the skin to become inflamed, forming swollen bumps 1 to 5 cm across.  These bumps most frequently occur on the shins, and sometimes the thighs and forearms as well.  The degree of inflammation may vary by day over a period of 3 to 6 weeks, after which time the bumps finally fade.  The affected area may appear bruised for a period of up to a few months afterward, but most patients experience a full recovery with no scars.  The cause is uncertain but is correlated with an over-reactive immune response following infection, medication, pregnancy, inflammatory conditions, vaccines, and autoimmune or other medical conditions.  Treatments are available to relieve discomfort. 

Patient Groups

Bloggers

None found.

Prevalence

US Cases: 3,200 - 16000 [Requena 2001]. 1-5 per 100,000 persons
For adults, EN is more common among women, with a male-to-female ratio of 1:6.

Typical Age of onset

Typically 18-34 years of age, but may occur at any age.
[Leung 2018]

Symptoms

EN has three consistent phases, before, initial breakout and after breakout. 

Before breakout:

  • Fever

  • Joint pain

  • Abdominal pain

  • Flu-like symptoms

Initial breakout:

  • Fever

  • Increased joint pain

  • Painful, symmetrical lumps 3-6 cm in diameter on the legs and knees, and sometimes thighs and forearms

  • Increased pain when standing

  • Swollen ankles

  • Enlarged lymph nodes

After breakout:

  • Lumps continue to grow for about 10 days

  • Lumps turn blue and yellow

  • Lumps disappear after 3-6 weeks