Cellulitis indicates nonnecrotizing inflammation of the skin and subcutaneous tissues

Cellulitis:

The term cellulitis is commonly used to indicate a nonnecrotizing inflammation of the skin and subcutaneous tissues, a process related to acute infection that does not involve the fascia or muscles and that is characterized by localized pain, swelling, tenderness, erythema, and warmth.

Cellulitis was classically considered to be an infection without formation of abscess and without purulent drainage or ulceration. In clinical practice, the division between cellulitis and abscess is not distinct. Frequently, the macular erythema of cellulitis coexists with nodules, areas of ulceration, and frank abscess formation.

Unlike impetigo, which is a very superficial skin infection, cellulitis is an infection that also involves the skin's deeper layers: the dermis and subcutaneous tissue. The main bacteria responsible for cellulitis are Streptococcus and Staphylococcus ("staph"), the same bacteria that can cause impetigo. MRSA (methicillin-resistant Staph aureus) can also cause cellulitis. Sometimes, other bacteria (for example, Hemophilus influenzae, Pneumococcus, and Clostridium species) may cause cellulitis as well.

Areas of occurence:

Cellulitis may occur anywhere on the body, but the lower leg is the most common site of the infection (particularly in the area of the tibia or shinbone and in the foot), followed by the arm, and then the head and neck areas. In special circumstances, such as following surgery or trauma wounds, cellulitis can develop in the abdomen or chest areas.

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