Signs and Symptoms of Cellulitis
Cellulitis presents with rapidly spreading areas of erythema (redness), swelling, tenderness, and warmth of the affected skin, often accompanied by lymphangitis and regional lymph node inflammation. 1
Primary Clinical Features
Cellulitis is an acute bacterial infection affecting the deep dermis and subcutaneous tissue. The cardinal signs include:
Skin changes:
Surface characteristics:
- Orange peel appearance (peau d'orange) due to superficial cutaneous edema around hair follicles
- Skin dimpling (follicles remain tethered to underlying dermis)
- Possible vesicles, bullae, and cutaneous hemorrhage (petechiae or ecchymoses) 1
Systemic Manifestations
While systemic symptoms are usually mild in uncomplicated cases, they may include:
- Fever or hypothermia
- Tachycardia (heart rate >100 beats/min)
- Confusion
- Hypotension (systolic BP <90 mm Hg or >20 mm Hg below baseline)
- Leukocytosis 1
Importantly, these systemic manifestations may sometimes appear hours before skin abnormalities become evident. 1
Warning Signs of Severe Infection
Pay particular attention to these indicators of potentially severe deep soft-tissue infection:
- Pain disproportionate to physical findings
- Violaceous bullae
- Cutaneous hemorrhage
- Skin sloughing
- Skin anesthesia (loss of sensation)
- Rapid progression
- Gas in the tissue 1
These signs often appear later in the course of necrotizing infections and warrant immediate surgical evaluation. 1
Laboratory Findings
For patients with signs of systemic toxicity, laboratory evaluation should include:
- Blood cultures
- Complete blood count with differential
- Creatinine, bicarbonate, creatine phosphokinase levels
- C-reactive protein 1
Hospitalization should be considered when patients present with:
- Hypotension
- Elevated creatinine level
- Low serum bicarbonate
- Elevated creatine phosphokinase (2-3× upper limit of normal)
- Marked left shift
- C-reactive protein >13 mg/L 1
Diagnostic Challenges
Cellulitis is frequently misdiagnosed due to several conditions that can mimic its presentation:
- Venous stasis dermatitis
- Contact dermatitis
- Deep vein thrombosis
- Eczema
- Panniculitis
- Lymphedema
- Erythema migrans 3, 2, 4
Misdiagnosis can lead to unnecessary hospital admissions and antibiotic overuse, as most alternative diagnoses are non-infectious. 4
Important Distinctions
The term "cellulitis" is not appropriate for cutaneous inflammation associated with collections of pus (e.g., septic bursitis, furuncles, or skin abscesses). When redness surrounds a suppurative focus, the correct terminology is "septic bursitis with surrounding inflammation" rather than "cellulitis." This distinction is clinically crucial because:
- Primary treatment for cellulitis is antimicrobial therapy
- For purulent collections, the major component of management is drainage of pus 1
Recognizing the true signs and symptoms of cellulitis is essential for accurate diagnosis and appropriate treatment, which directly impacts patient morbidity and mortality.