Erythema: Definition and Clinical Significance
Erythema is redness of the skin caused by increased blood flow in superficial capillaries, typically resulting from inflammation, infection, or other pathological processes. 1
Types and Clinical Presentations of Erythema
Erythema can manifest in various forms, each with distinct clinical features:
1. Cellulitis and Erysipelas
- Cellulitis: Diffuse, superficial spreading skin infection involving deeper dermis and subcutaneous fat
- Erysipelas: More superficial infection limited to upper dermis and superficial lymphatics, with well-demarcated borders 1
- Often presents on the face
- In European countries, sometimes used synonymously with cellulitis
2. Erythema Migrans
- Characteristic expanding erythematous skin lesion of Lyme disease
- Typically appears 7-14 days (range 3-30 days) after tick bite
- Should be at least 5 cm in diameter for secure diagnosis
- May have central clearing or target-like appearance
- Not scaly unless long-standing or treated with topical corticosteroids 1
3. Erythema Multiforme
- Acute immune-mediated disorder affecting skin and/or mucous membranes
- Characterized by target or iris lesions distributed symmetrically on extremities and trunk
- Often triggered by infections (particularly herpes simplex virus) or medications 2, 3
4. Palmar-Plantar Erythrodysesthesia Syndrome (PPES)
- Also called hand-foot syndrome or acral erythema
- Characterized by redness, discomfort, swelling, and tingling in palms and soles
- Associated with certain chemotherapeutic agents 1
5. Erythema Nodosum
- Painful disorder of subcutaneous fat (panniculitis)
- Presents as tender, erythematous subcutaneous nodules, typically on anterior lower extremities
- May be idiopathic or associated with systemic diseases 4
Clinical Features of Erythema
Regardless of specific type, erythema commonly presents with:
- Redness (from increased blood flow to affected area)
- Warmth
- Tenderness or pain
- Swelling or edema
- Sometimes accompanied by systemic symptoms (fever, malaise) 1
In cellulitis and erysipelas specifically, erythema may be accompanied by:
- Lymphangitis
- Regional lymph node inflammation
- Skin dimpling (peau d'orange appearance) due to superficial cutaneous edema
- Vesicles, bullae, or cutaneous hemorrhage in some cases 1
Diagnostic Approach
Diagnosis of erythema is primarily clinical, based on:
- Visual inspection of skin lesions
- Pattern and distribution of erythema
- Associated symptoms
- Relevant history (recent infections, medication use, tick exposure)
For specific types like erythema migrans, visual inspection is the preferred diagnostic method, as serologic testing is too insensitive in early infection 1.
Management Principles
Treatment depends on the underlying cause:
For infectious causes (cellulitis, erysipelas):
- Antibiotics active against Gram-positive bacteria, particularly streptococci
- For mild cases: Oral beta-lactams, macrolides, or lincosamides
- For severe cases: Parenteral antibiotics
- If MRSA suspected: Glycopeptides or newer antimicrobials 1
For erythema migrans (Lyme disease):
- Appropriate antibiotic therapy based on clinical findings 1
For drug-induced erythema:
- Discontinuation of offending medication
- Symptomatic treatment 2
For chemotherapy-associated PPES:
- Dose modification of causative agent
- Supportive care 1
Important Considerations
- Erythema is a symptom, not a diagnosis itself - identifying the underlying cause is essential for proper management
- Some forms of erythema (like erythema migrans) have distinctive appearances that allow clinical diagnosis without laboratory confirmation
- Severity can range from mild, localized redness to extensive involvement with systemic symptoms
- Prompt recognition and appropriate management can prevent progression to more serious complications