Cellulitis is an acute inflammation of the connective tissue of the skin, caused by infection with staphylococcus, streptococcus or other bacteria

Clinical Presentation

Cellulitis occurs as a tender, edematous, bright red plaque 5 to 20 cm in diameter. Generally, only a single lesion is present. A thin red line progressing proximally from the lesion (lymphangitis) is seen in about 20% of patients The initial lesion of cellulitis appears suddenly. Centrifugal growth of the lesion is rapid during the first 24 hours but occurs more slowly thereafter. Cellulitis is quite tender, but it is less painful than furunculosis, and fluctuant areas never develop. Fever, malaise, and regional lymphadenopathy may or may not be present.

Differentiation of cellulitis from an acute urticarial plaque such as occurs following bee stings is sometimes difficult, but the course of events over the succeeding 24 hours generally allows for appropriate identification.

The diagnosis of cellulitis is made on a clinical basis. It is theoretically possible to culture the lesion by way of injection, and subsequent aspiration, of sterile saline, but most clinicians do not find this helpful or necessary.

Course and Prognosis

Most instances of cellulitis resolve spontaneously over 10 to 20 days. Unfortunately, in debilitated or otherwise immunocompromised patients there may be progressive spread, and systemic infection may develop. The process is particularly troublesome when it occurs in patients taking systemic steroids, since not only is resistance reduced but the signs and symptoms of the infection may be greatly masked by the anti-inflammatory action of the steroids.

Special attention should be given to cellulitis of the central face, since, if it is left untreated, there is a significant risk of extension to the cavernous sinus.

Cellulitis is not usually recurrent. In patients with chronic lymphedema, however, there is a tendency both for the development of multiple lesions and for the occurrence of repeated episodes. The presence of hypesthesia, anesthesia, or blister formation (especially if the fluid is yellow or hemorrhagic) over an area of cellulitis should alert the clinician to the possible presence of underlying necrotizing jasciitis.

Pathogenesis

Cellulitis is a nonfollicular, mid to deep dermal infection caused by Staphylococcus aureus or Streptococcal pyogenes. Clinical signs indicating which of the two organisms is responsible are unreliable, but lymphangitis is more commonly found in staphylococcal infection. Fever, on the other hand, is more often seen in streptococcal infection. Trauma to the skin predisposes to the development of cellulitis, but occurrence ill the absence of trauma is common. Patients with chronic lymphedema seem particularly susceptible to the development of cellulitis.

Therapy

Systemic antibiotics, the treatment of furunculosis should be administered to all patients with cellulitis. It is not necessary to decide whether the problem is staphylococcal or streptococcal before initiating therapy, and in fact, culture is usually not possible even with saline injection and aspiration . Incision and irainage are never carried out. Hot packs or hot soaks are often recommended, but there is little evidence that this approach speeds resolution.

Treatment:

Cellulitis treatment may require hospitalization if it is severe enough to warrant intravenous antibiotics and close observation. At other times, treatment with oral antibiotics and close outpatient follow-up is enough. Treatment is focused on control of the infection and prevention of complications.