Cellulitis Examination Findings
Cardinal Clinical Features
Cellulitis presents with rapidly spreading erythema, swelling, tenderness, and warmth of the affected skin, sometimes accompanied by lymphangitis and regional lymph node inflammation. 1
The diagnosis is clinical and based on the presence of at least 2 of the cardinal manifestations of inflammation: redness, warmth, swelling or induration, and pain or tenderness 1. Purulent secretions (pus) may also be present 1.
Specific Physical Examination Findings
Skin Surface Changes
- Peau d'orange appearance: The skin surface may resemble an orange peel due to superficial cutaneous edema surrounding hair follicles, causing skin dimpling because the follicles remain tethered to the underlying dermis 1
- Vesicles, bullae, and cutaneous hemorrhage in the form of petechiae or ecchymoses may develop 1
- Well-demarcated borders with fiery red appearance suggest erysipelas rather than typical cellulitis 1
Tissue Characteristics
- Yielding subcutaneous tissues: In cellulitis or erysipelas, the subcutaneous tissues can be palpated and are yielding, distinguishing it from necrotizing fasciitis 1
- Induration and tenderness are typical findings 1
- Warmth over the affected area is consistently present 2, 3
Systemic Manifestations
- Fever, tachycardia, confusion, and hypotension may be present and can occur hours before skin abnormalities appear 1
- Leukocytosis frequently accompanies cellulitis 1
- Systemic manifestations are usually mild but can indicate severe infection requiring hospitalization 1
Critical Distinguishing Features
What Cellulitis Is NOT
The term "cellulitis" is not appropriate for cutaneous inflammation associated with collections of pus, such as septic bursitis, furuncles, or skin abscesses 1. When cutaneous redness, warmth, tenderness, and edema encircle a suppurative focus, the appropriate terminology is "septic bursitis with surrounding inflammation" rather than "septic bursitis with surrounding cellulitis" 1.
Warning Signs of Necrotizing Infection
- Wooden-hard feel of subcutaneous tissues: In necrotizing fasciitis, the underlying tissues are firm and fascial planes and muscle groups cannot be discerned by palpation, contrasting with the yielding tissues in cellulitis 1
- Anesthesia of involved skin occurs frequently in necrotizing fasciitis 1
- Skin discoloration or gangrene (70% of necrotizing fasciitis cases) 1
- Broad erythematous tract along the route of infection as it advances 1
Common Cellulitis Mimics to Consider
When examining a patient with suspected cellulitis, actively assess for these alternative diagnoses:
- Venous stasis dermatitis: Look for bilateral involvement, chronic changes, and absence of acute systemic symptoms 2, 4
- Deep vein thrombosis: Assess for unilateral leg swelling, calf tenderness, and risk factors 5, 4
- Contact dermatitis: Look for exposure history and distribution pattern 2
- Gout: Examine for joint involvement and crystal deposition 5, 4
- Eczema: Frequently mistaken for cellulitis 4
Essential Examination Components
Local Assessment
- Measure and record wound size if present, extent of surrounding erythema, and quality/quantity of drainage (color and odor) 1
- Probe any wounds with a sterile, blunt metal probe to measure depth, detect foreign bodies, soft-tissue abscesses, or palpable bone 1
- Examine interdigital toe spaces for tinea pedis, fissuring, scaling, or maceration, as these predispose to cellulitis 6
Systemic Assessment
- Check vital signs for fever (>38°C), tachycardia (>90 bpm), tachypnea (>24 rpm), or hypotension 6
- Assess mental status for confusion or altered consciousness 1, 6
- Palpate regional lymph nodes for lymphadenitis 1
When Cultures Are Indicated
Blood cultures, tissue aspirates, or skin biopsies are unnecessary for typical cases of cellulitis 1. However, obtain cultures for patients with: