Erythema nodosum is an inflammatory affection, of an acute type, characterized by the formation of variously-sized, roundish, more or less elevated erythematous nodes. #Is there any special region of predilection for the eruption of erythema nodosum?# Yes. The tibial surfaces, to which the eruption is often limited; not infrequently, however, other parts may be involved, more especially the arms and forearms. #Describe the symptoms of erythema nodosum.# The eruption makes its appearance suddenly, and is usually ushered in with febrile disturbance, gastric uneasiness, malaise, and rheumatic pains and swelling about the joints. The lesions vary in size from a cherry to a hen's egg, are rounded or ovalish, tender and painful, have a glistening and tense look, and are of a bright red, erysipelatous color which merges gradually into the sound skin. At first they are somewhat hard, but later they soften and appear as if about to break down, but this, however, never occurs, absorption invariably taking place. In occasional instances they are hemorrhagic. Exceptionally the lesions of erythema multiforme are also present. Lymphangitis is sometimes observed. In rare instances symptoms pointing to visceral involvement, to cerebral invasion, and to heart complications have been observed. #Are the lesions in erythema nodosum usually numerous?# No. As a rule not more than five to twenty nodes are present. #What is the course of erythema nodosum?# Acute. The disease terminating usually in one to three weeks. As the lesions are disappearing they present the various changes of color observed in an ordinary bruise. #What is known in regard to the etiology?# The affection is closely allied to erythema multiforme, and is, indeed, by some considered a form of that disease. It occurs most frequently in children and young adults, and usually in the spring and autumn months. Intestinal toxins are thought responsible in some cases. Digestive disturbance and rheumatic pain and swellings are often associated with it. By many the malady is thought to be a specific infection. #What is the pathology of erythema nodosum?# The disease is to be viewed as an inflammatory [oe]dema, probably resulting, in some instances at least, from an inflammation of the lymphatics or an embolism of the cutaneous vessels. #What diseases may erythema nodosum resemble?# Bruises, abscesses, and gummata. #How are the lesions of erythema nodosum to be distinguished from these several conditions?# By the bright red or rosy tint, the apparently violent character of the process, the number, situation and course of the lesions. #State the prognosis of erythema nodosum.# Favorable, recovery usually taking place in ten days to several weeks. #State the treatment to be advised in erythema nodosum.#