Sir: Acute febrile neutrophilic dermatosis
or Sweet's syndrome' is an uncommon condition
characterised by fever, polymorphonuclear
leucocytosis, painful erythematous
cutaneous plaques, and a dense dermal infiltrate
of neutrophils without vasculitis at the
site of the skin lesions. Although many
investigators suggest that acute febrile neutrophilic
dermatosis is a hypersensitivity reaction,2
no defmitive cause is known. The role
of the neutrophil as a cause or effect in this
syndrome has not been clarified. Acute febrile
neutrophilic dermatosis is histologically and
clinically mimicked by several disorders, and
the differential diagnosis with pyoderma gangrenosum3
and with some reactive erythemas
such as erythema multiforme2 is usually difficult
