Abstract
A male child, aged 4, developed erythema nodosum following streptococcal infection. Direct immunofluorescent study revealed the deposit of IgG, A and complement within and around the blood vessel wall in the dermal subcutaneous portion. Histopatho-logically, the same blood vessel showed slightly neutrophilic vasculitis. These observations suggest that this case relates to an allergic reaction of arthus type.