Contents
Acute bacterial infection of the dermis and hypodermis associated with clinical inflammation.
- Also known as St. Anthony’s fire
- Specific clinical type of cellulitis studied as a specific entity
Aetiology
Streptococcus pyogenes (β-hemolytic group A streptococci)
Primary organism responsible
- Minor trauma, insect bites, dog bites, eczema, athlete’s foot, surgical incisions and ulcers
- Athlete’s foot (M/C portal of entry)
Clinical features
Well-demarcated erythematous skin lesion with raised edges:
After a sudden onset, areas of erythema and edema characteristically enlarge with well-defined margins.
- Sites: Leg (M/C) > Face, arm, and upper thigh
Associated features:
- High fever
- Adenopathy and lymphangitis
Milian’s ear sign:
The pinna has no deeper dermis and subcutaneous tissue so redness there cannot be cellulitis.

Differential diagnosis:
All of which present with erythema, warmth, edema, and pain
- Cellulitis: Erysipelas is more superficial than cellulitis and is typically more raised and demarcated
- Others: Abscess, felon, gout, and paronychia

Management
Penicillin monotherapy:
First-line antibiotic used for the treatment of erysipelas