Differential Diagnosis for Cellulitis
Single Most Likely Diagnosis
- Cellulitis: This is the most likely diagnosis given the presentation of cellulitis, which is a common bacterial skin infection characterized by redness, swelling, warmth, and pain in the affected area. The typical causative organisms are Streptococcus and Staphylococcus species.
Other Likely Diagnoses
- Eczema (Dermatitis): Can present with similar skin changes, including redness and swelling, but usually has a more chronic course and is associated with itching.
- Contact Dermatitis: An allergic or irritant reaction to substances coming into contact with the skin, which can mimic cellulitis but typically has a clearer history of exposure to an offending agent.
- Insect Bites or Stings: Can cause localized reactions that might be confused with cellulitis, especially if there are multiple bites or a severe reaction.
- Deep Vein Thrombosis (DVT): While not an infection, DVT can cause swelling, redness, and warmth of the leg, which might be mistaken for cellulitis, especially in the absence of a clear infectious history.
Do Not Miss Diagnoses
- Necrotizing Fasciitis: A severe, life-threatening infection that destroys the tissue under the skin, including fat and the tissue covering the muscles (fascia). It requires immediate medical attention and can be mistaken for cellulitis in its early stages.
- Gas Gangrene: Caused by Clostridium perfringens, this condition is characterized by the production of gas in tissues and can lead to rapid tissue death and systemic toxicity. It is a medical emergency.
- Erysipelas: A type of skin infection that involves the upper dermis, typically caused by Streptococcus, and can be distinguished from cellulitis by its well-demarcated borders and usually affects the face or legs.
Rare Diagnoses
- Erythema Migrans (Lyme Disease): The rash associated with early Lyme disease can sometimes be confused with cellulitis, though it typically has a distinctive "bull's-eye" appearance.
- Sweet Syndrome (Acute Febrile Neutrophilic Dermatosis): A rare condition characterized by fever, neutrophilia, and tender, erythematous skin lesions that can mimic infections like cellulitis.
- Pyoderma Gangrenosum: A rare skin condition that can cause painful ulcers, which might be mistaken for an infectious process like cellulitis, especially if there's significant surrounding inflammation.