Erythema Nodosum (EN) refers to a condition of inflammation of fat cells, present beneath the outer layers of the skin. Like rosacea, it results in swollen, sore and reddened nodules and protuberances, but mainly in the skin of the shin, which is located in the lower front portion of the legs. Also Read: Rosacea: Causes, Symptoms And Treatment

Although erythema nodosum affects people of all ages, it is most common between the ages of 10 to 30 and occurs more frequently in women than in men.

erythema nodosum

The majority of instances of erythema nodosum will eventually resolve on their own, with minimal to no medications. However, in some rare severe instances, erythema nodosum could indicate chronic infections, cancers, or drug allergies and hence requires prompt medical treatment. It is thus advised to understand the underlying factors and signs involved in erythema nodosum and seek immediate care from a doctor if any external marks or spots are seen on the skin in the shin region.


Various reasons could trigger a case of erythema nodosum, such as:

Infectious Diseases:

  • Streptococcal infections
  • Tuberculosis
  • Pneumonia
  • Epstein-Barr virus
  • Cat scratch disease

Immune System Disorders:

Medication Allergies:

  • Penicillin
  • Bromides
  • Sulphur-containing compounds


  • Lymphoma
  • Pancreatic cancer
  • Neuroendocrine tumour


The distinguishing indicators of erythema nodosum include:

  • Slightly bulging, tender nodules on the skin below the knees
  • Flat, hardened and painful nodules in the skin on the lower legs, as well as other parts of the body
  • Frequent joint pain
  • Mild fevers
  • Widespread red patches on the skin

Diagnosis And Treatment

The diagnosis of erythema nodosum is usually performed by means of skin patch test and external examination by the doctor, of the affected areas of the skin in the patient. Yet, in some situations, erythema nodosum could be mistaken for cellulitis or even an insect bite. Also Read: Cellulitis: Causes, Symptoms And Treatment

Thus, it is essential to conduct laboratory tests to obtain an accurate diagnosis of EN, so that appropriate treatment measures can be initiated.

When the medical expert is uncertain of the reason behind the painful, red patches, lumps or nodules on the skin of the patient, he or she performs a skin biopsy. Upon analysing the skin tissue excised from the patient under a microscope, the walls or septal portions of fat cells and blood vessels in the dermatological layers display prominent thickening. This confirms the diagnosis of erythema nodosum.


A minor instance of erythema nodosum will usually subside on its own, causing only mild symptoms. Although the inflamed red lumps or nodules may remain on the skin’s surface for about 3 to 6 weeks, other complications like fever or joint pain might be negligible or even completely absent.

In grave situations of aching in the bones, muscles and constant discomfort and fatigue in the body, adequate rest, along with leg elevating movements and using compressive bandages help in alleviating the signs of uneasiness. The physician will also prescribe oral anti-inflammatory drugs or administer an injection of the same in the affected areas of the skin in the legs.

These remedial procedures rectify the case of erythema nodosum and avert any further complications to other internal organs in the body, ensuring the complete recovery of the patient.