Cellulitis involves the deep dermis and subcutaneous tissue. Erysipelas is primarily an infection of the dermis with significant lymphatic involvement. It has a distinctive clinical presentation and it is most often caused by streptococcus pyogenes.
Epidemiology and Pathogenesis
A disease of the very young, the aged, the debilitated, and those with lymphedema or chronic cutaneous ulcers. A female predominance exists, except in young patients, where it is more commonly seen in boys. There is increased frequency during the summer months. Most cases are isolated. Most cases of erysipelas are caused by infection with GAS, and less often by groups G, B, C, and D streptococci.
Classically erysipelas, with its well-defined margins, involves the face. The lower extremity is now the most common location. The incubation period ranges from 2 to 5 days. It is characterized by an abrupt onset of fever, chills, malaise, and nausea. A few hours to a day after these symptoms, a small plaque of erythema develops that progressively spreads. The area is clearly demarcated from uninvolved tissue, hot, tense, indurated, and demonstrates non-pitting edema. The affected area is painful to palpation and may burn. Regional lymphadenopathy is normally present, with or without lymphatic streaking. Pustules, vesicles, bullae, and small areas of hemorrhagic necrosis may also form.
Rare and usually occur in patients with underlying diseases. When the infection resolves, desquamation and post inflammatory pigmentary changes may occur.