Sweet's syndrome: unique local response to streptococcal antigen.

Although hypersensitivity has been postulated, the etiology of Sweet's syndrome has never been elucidated. In the present case intradermal tesing with viridans streptococcus led to an immediate reaction and reproduced a lesion clinically and histologically identical to that of the primary disease. Other bacterial and fungal antigens failed to elicit any response. These findings provide further support for the role of hypersensitivity in the pathogenesis of this disorder. It would appear that immediate or humoral immunit