Cellulitis

Essentials of Diagnosis

• Edematous, expanding, erythematous, warm plaque with or without vesicles or bullae

• Lower leg is frequently involved

• Pain, chills, and fever are commonly present

• Septicemia may develop

General Considerations

• Usually due to gram-positive cocci, though gram-negative rods or even fungi can produce similar picture

• The major portal of entry for lower leg cellulitis is toe web tinea pedis with fissuring of the skin at this site

• Erysipelas is a superficial form of cellulitis that occurs classically on the cheek, caused by β-hemolytic streptococci (see Erysipelas)

Symptoms and Signs

• Lesion begins as a small batch and expands over hours

• Edematous, expanding, erythematous, warm plaque with or without vesicles or bullae

• Pain at the lesion, malaise, chills, and moderate fever

• Usually on the lower leg

• Lymphangitis and lymphadenopathy may be present

• Progressive chills, fever, and malaise

• Septicemia and septic shock may develop

Differential Diagnosis

• Deep venous thrombosis

• Venous stasis

• Candidiasis

• Anthrax

• Contact dermatitis

• Herpes zoster (shingles)

• Scarlet fever

• Angioedema

• Necrotizing fasciitis

• Sclerosing panniculitis

• Underlying osteomyelitis

• Systemic lupus erythematosus

• Erysipeloid

Laboratory Tests

• Attempts to isolate the responsible organism by injecting and then aspirating saline are successful in 20% of cases

• Leukocytosis and an increased sedimentation rate are almost invariably present but are not specific

• Blood cultures may be positive

• Skin biopsy is particularly helpful in an immunocompromised patient whose cellulitis may be due to an uncommon organism

Diagnostic Procedures

• ALT-70 is a predictive model to diagnose cellulitis or a cellulitis mimic and to provide guidance about when a dermatology consultation is needed

  • Variables are

    • Asymmetry (3 points)

    • Leukocytosis of 10,000/mcL or more at presentation (2 points)

    • Tachycardia above 90 beats per minute (1 point)

    • Age 70 years or older (1 point)

  • Score above 5 carries more than an 82% chance of a true cellulitis while a score below 2 suggests a greater than 83% chance of a cellulitis mimicker

Medications

• Intravenous or parenteral antibiotics effective against group A β-hemolytic streptococci and staphylococci may be required for the first 24–48 hours

• Dicloxacillin or cephalexin, 250–500 mg four times daily orally for 5–10 days, is usually adequate for mild cases or following initial parenteral therapy

• In patients in whom intravenous treatment is not instituted, the first dose of oral antibiotic can be doubled to achieve rapid high blood levels

• Oral penicillin 250 mg twice daily or oral erythromycin 250–500 mg twice daily can decrease the risk of recurrence in patients with recurrent lower leg cellulitis (three to four episodes per year)

Prevention

• Measures to prevent recurrences include

  • Compression

  • Treating toeweb intertrigo and tinea pedis

  • Controlling venous insufficiency

Prognosis

• The rare infective endocarditis due to E rhusiopathiae may have mortality rates as high as 30–40% despite surgery, even in immunocompetent individuals

When to Refer

• If there is a question about the diagnosis, if recommended therapy is ineffective, or if specialized treatment is necessary

When to Admit

• Severe local symptoms and signs

• Signs of sepsis

• Elevated white blood cell count of 10,000/mcL or more with marked left shift

• Failure to respond to oral antibiotics