Erythema nodosum is a type of panniculitis, an inflammatory disorder affecting subcutaneous fat. It presents as tender red nodules on the anterior shins. Less commonly, they affect the thighs and forearms.
Up to 55% of patients will have an unknown cause for erythema nodosum. In other cases, it is associated with an identified infection, drug, inflammatory condition, or malignancy. Infections include throat infections (streptococcal disease disease or viral infection), Primary tuberculosis (TB), Yersinia, Chlamydia infection; fungal infections such as histoplasmosis, coccidioidomycosis and parasitic infection like amoebiasis and giardiasis.
Erythema nodosum is treated based on the underlying disease.Pain management including extended rest, analgesia and steroids may be prescribed if infection, sepsis, and malignancy have been ruled out.