Definition

Erythema nodosum is the name given to tender lumps on the legs and sometimes the arms. They are caused by inflammation of the fat or connective tissue beneath the skin.

Erythema Nodosum Copyright © Nucleus Medical Media, Inc.

Causes

Erythema nodosum is thought to be a type of autoimmune reaction. It may be caused by:

• Infections from a:
  • Virus
  • Bacteria, especially strep throat
  • Fungus
• Inflammatory conditions:
  • Ulcerative colitis
  • Crohn’s disease
  • Sarcoidosis
• Medications:
  • Sulfa drugs and some other antibiotics
  • Iodides
  • Bromides
  • Birth control pills
  • Leukotriene modifiers
  • Proton pump inhibitors
• Certain types of cancer:
  • Lymphoma
  • Leukemia

Sometimes the cause of erythema nodosum is not known.

Risk Factors

This condition is rare. It is more common in females and young adults aged 20-30 years old.

Having any of the causes listed above will only slightly increase your risk of the disorder.

Symptoms

Symptoms include:

• Very tender, deep lumps, like bruises, that change color in the same way, from pink to blue to brown:
  • Usually located on your shins
  • May also appear on the forearms, trunk, neck, and head
• May be associated joint pain and fever and redness around the eyes

Diagnosis

You will be asked about your symptoms and medical history. A physical exam will be done, which may diagnose the problem based on a visual exam. You may be referred to a doctor that focuses on skin problems or infectious diseases.

Your bodily fluids and cells may be tested to look for a cause. This can be done with:

• Blood and urine samples
• Cultures or a throat swab for strep
• PPD skin test for tuberculosis
• Biopsy of a lesion

Images may be taken of your bodily structures. This can be done with a chest x-ray and other imaging tests.

Treatment

If a cause can be identified, it will be treated. For the nodules themselves, pain relief is all that is needed. They tend to resolve on their own in about 6 weeks. They will not cause scarring. Treatment options include the following:

Prevention

Some of the infectious causes can be avoided by practicing good hygiene, which includes:

• Washing your hands often
• Not sharing food, drinks, or utensils