What is Erysipelas?
Erysipelas is a diffuse, superficial bacterial skin infection involving the upper dermis and superficial lymphatics, characterized by rapidly spreading erythema with sharply demarcated, raised borders, most commonly caused by group A β-hemolytic streptococci. 1
Terminology and Classification
The term "erysipelas" has three distinct clinical meanings that vary by geographic region and clinical tradition 1:
- Anatomic definition: An infection limited to the upper dermis and superficial lymphatics, whereas cellulitis involves deeper dermis and subcutaneous fat, with erysipelas having more clearly delineated borders 1
- Location-based definition: Used by many clinicians to refer specifically to cellulitis involving the face only 1
- Synonymous usage: In European countries, cellulitis and erysipelas are often used interchangeably 1
Important distinction: Erysipelas refers to diffuse spreading skin infections and should not be used for cutaneous inflammation associated with purulent collections like abscesses, furuncles, or septic bursitis, as these require drainage rather than antibiotics alone. 1
Clinical Presentation
Primary Features
- Rapid onset with sudden appearance of erythema, swelling, tenderness, and warmth 1, 2
- Well-defined, raised margins that distinguish it from other forms of cellulitis 1, 2
- Peau d'orange appearance: Orange peel-like skin surface due to superficial edema surrounding hair follicles causing dimpling where follicles remain tethered to underlying dermis 1
- Regional lymphangitis and inflammation of regional lymph nodes frequently present 1, 2
Cutaneous Manifestations
- Vesicles, bullae, and cutaneous hemorrhage (petechiae or ecchymoses) may develop on inflamed skin 1
- Lower legs are the most common location (85% of cases), followed by face, arms, and upper thighs 2, 3
Systemic Features
- High fever is characteristic and often accompanies the infection 2, 3, 4
- Fever, tachycardia, confusion, hypotension, and leukocytosis may occur hours before skin abnormalities appear 1
- Systemic manifestations are usually mild but can be severe 1
Microbiology
- Primary pathogen: Group A β-hemolytic Streptococcus (Streptococcus pyogenes) 2, 3, 4
- Alternative pathogens: Staphylococcus aureus (particularly in bullous erysipelas, with 50% isolation rate and frequent MRSA involvement), other streptococci (groups B, C, D) 5, 6
- Streptococcal toxins likely contribute to the clinical inflammation 2
Predisposing Factors and Entry Points
- Athlete's foot is the most common portal of entry 2, 4
- Venous insufficiency, lymphatic obstruction, and edema from various causes 1, 6
- Local trauma, preexisting skin infections, ulceration, fissured toe webs from maceration or fungal infection 1
- Inflammatory dermatoses such as eczema 1, 4
- Obesity and previous cutaneous damage 1
Note: This definition focuses on the clinical entity itself. Treatment recommendations prioritizing morbidity and mortality outcomes are addressed separately in treatment guidelines.