Disorders Which May Be Mistaken for Cellulitis
| Disorder | Distinguishing features |
|---|---|
Necrotizing fasciitis Leg eczema (venous eczema or contact dermatitis) (NB cellulitis may complicate eczema) Deep vein thrombosis (DVT) (NB cellulitis may complicate DVT) Allergic reaction to insect sting or bite | Ill patient Severe pain, disproportionate to physical signs Skin may be very tender, with blue-black discolouration and blistering Rapid clinical progression Longer history May be bilateral (bilateral cellulitis is rare) No fever or systemic symptoms Itching rather than tenderness of the skin History of varicose veins or DVT Crusting or scaling (in cellulitis the skin is typically smooth and shiny) Proximal margin of erythema usually not well demarcated If clinical setting suggests DVT (Chapter 56), duplex scan of leg veins needed to exclude this No ascending lymphangitis Itching |
| Disorder | Distinguishing features |
|---|---|
| Chronic oedema/ | Usually bilateral |
| lymphoedema | Erythema may be feature |
| (NB cellulitis may complicate chronic oedema or lymphoedema) | No fever |
| Gouty arthritis | Arthritis prominent |
| Typically involves first metatarsophalangeal joint (Chapter 97) | |
| Pyoderma | Rapidly enlarging painful ulcer |
| gangrenosum | Associated systemic disease (most often inflammatory bowel disease) in 50% |