Wells' syndrome is a rare inflammatory eosinophilic dermatosis. It typically appears as a sudden-onset of one or multiple inflammatory plaques associated with a pruritus. General symptoms are rare. There is often blood eosinophilia and a marked dermal eosinophilic infiltrate with flame figures on skin biopsy. Numerous trigger factors and associated diseases are described. The etiology is unclear. Most experts believe it to be a type IV hypersensitivity reaction in predisposed individuals with an imbalance TH1/TH2 cells. Circulating TH2 cells may be implicated by producing IL- 5 which stimulates eosinophils' degranulation. The aim of this article is to review the diagnostic and therapeutic options of this pathology knowing that the main differential diagnosis is cellulitis of infectious origin.