History:

Sweet's Syndrome or Acute Febrile Neutrophilic Dermatosis was first described in 1964 by Dr Robert Sweet.It is a reaction pattern in the skin with associations with bacterial and viral infections,underlying neoplasias,particularly hematological malignancy,inflammatory disease and even pregnancy.

In the above case the lesions appeared suddenly on the lower limbs with associated fever and tenderness.They looked like a vasculitis clinically but the lesions were very well circumscribed and more raised because of dermal inflammation and oedema than you would see in the typical case of vasculitis.No underlying cause was found .The patient responded quickly to high dose oral Prednisolone which was tapered off over a 3 week period.This reference from The Dermatology Online Journal  is a good summary of the condition and its treatment.