Atypical neutrophilic dermatosis on the upper extremity affected by postmastectomy lymphedema: report of 2 cases.

We describe 2 female patients, both with a history of radical mastectomy for breast cancer, in whom several indurated erythematous plaques developed on the upper extremity affected by postmastectomy lymphedema. There were no general symptoms or leukocytosis. Histopathological examination showed a dense neutrophilic infiltrate without a feature of vasculitis in the dermis and subcutis. Dramatic therapeutic response was observed to treatment with potassium iodide. These findings resemble Sweet's syndrome, but such cases have not been previously reported. Possible pathogenic mechanisms for these unique cutaneous eruptions are discussed.