Erythema nodosum is always stereotypical in its evolution and involving three successive phases

1/ Phase prodromique

Erythema nodosum is sometimes preceded by ENT or respiratory infection high 1 to 3 weeks before the rash, suggestive of streptococcal origin. Most often, only one fever, joint pain, sometimes abdominal pain…

2 / Status phase

The nouures (kinds of balls under the skin, badly limited) settle in 1 to 2 days on the extension faces of the legs and knees, more rarely thighs and forearms. They are of variable size (1 to 4 cm), few (3 to 12 lesions), bilateral but not symmetrical. They are painful (pain accentuated by standing), warm, firm. There is often a ankle edema and persistent joint pain.

3 / Regression phase

It is all the earlier that the treatment is well followed. Each knot evolves in ten days, taking on blue-green and yellowish aspects., like the evolution of a hematoma. The knots disappear without sequel. Erythema nodosum may include several pushes over 1 to 2 months, favored by the standing position.

Is it necessary to do examinations in case of erythema nodosum?

The doctor is looking for a cause erythema nodosum in order to treat it. He has examinations carried out most often directed by clinical signs (stool analysis in case of diarrhea only for example):

Blood test with formula count of blood cells (red blood cells, white blood cells, etc.), liver test, search for inflammation, search for antistreptolysin O (ASLO) and antistreptodornases (ASD), tuberculin tests, dosage of the conversion enzyme of angiotensin, serodiagnosis of yersiniosis, rthorax adiography.