Suppression of erythema nodosum by indomethacin.

Erythema nodosum (EN) can be a debilitating illness. Many treatment modalities have been suggested but none is universally effective. We describe three patients with severe EN secondary to streptococcal pharyngitis who were unresponsive to large doses of aspirin. Following the administration of indomethacin in doses of 100 to 150 mg per day, all three showed a dramatic response, with prompt resolution both of systemic symptoms and of local signs of inflammation. The lesions of EN involve the lower cutis, with inflammation of septae and fat lobules. It is likely, therefore, that the local liberation of fatty acids leads to increased prostaglandin synthesis which, in turn, is responsible for the intense inflammation. The impressive suppression of EN by indomethacin could be related to the inhibition of prostaglandin synthetase in the subcutaneous fatty tissues.