Erythema nodosum, also known as EN, is an inflammation of the skin characterized by soft, reddish, painful nodules or lumps that originate from the skin’s fatty subcutaneous part. Very frequently, patients suffering from EN have these nodules or lumps in the front of the legs, just right below the knees. EN is the most common form of panniculitis – these are a group of disorders characterized by painful bumps, or nodules, that form under the fatty subcutaneous part of the skin and are often found on the feet and legs.

The reddish, painful nodules or lumps found in erythema nodosum range from the size of a dime to the size of a quarter. The inflammation can go on and off for several weeks, then become flat and shrink down, marking the area with a bruised appearance but only temporarily.

By itself, EN can go away within a span of three weeks up to six weeks. After it’s gone, it can leave either a bruised appearance or a chronic indented mark located on the fatty part of the injured skin, but these are only temporary.


A chronic version of erythema nodosum is a medical condition that occurs for a period ranging from weeks to months in which lesions appear in various parts of the patient’s body. Another characteristic of the chronic variant of erythema nodosum is that it can last for years. Chronic erythema nodosum can happen regardless of whether or not a patient has an underlying medical condition.


Painful, symmetric, reddish lumps or nodules are commonly located on the front anterior part of the legs that shrink down in a matter of weeks with a temporary bruised appearance.


The medical professional would perform a physical exam which is the primary form of diagnosis. A biopsy or medical procedure in which a small part of the inflamed skin is excised, is sometimes performed to examine the condition more closely and to confirm if it is erythema nodosum. The following are diagnostic tests performed (under the guidance of a medical professional) to determine if a patient is suffering from erythema nodosum:

  • Purified protein derivative test
  • Complete blood count
  • Chest radiography
  • Stool culture


Erythema nodosum is treated and managed first by identifying if the patient has any underlying medical disorders or conditions. The treatments for erythema nodosum can include nonsteroidal anti-inflammatory drugs and cortisone, administered either orally or thru injection. A daily dosage of 1 mg per kg of systemic steroids can be given until such time the condition heals. Colchicine is a medication sometimes used to decrease the intensity of the inflammation effectively.

A personal and customized treatment must be the norm for a particular patient, taking into account his or her symptoms. It is very important to remember that although the occurrence of erythema nodosum is often painful and very uncomfortable, it does not threaten any vital organs. In the long term, the prognosis is usually very good.

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