Erythema Nodosum

Erythema nodosum is a condition of red, painful nodules that form under the skin, usually over the shins or on the soles of the feet. This condition is most often a result of immune system cross-reaction to infection, typically streptococcal infection, but may also be associated with more serious infections such as tuberculosis, and can be a first manifestation of inflammatory bowel disease, especially Crohn disease. The painful knots flatten and turn brown; they may be then mistaken for bruises.