Cellulitis
Updates to Article Attributes
Cellulitis is an acute infection of the dermis and subcutaneous tissues. It results in pain, erythema, oedema, and warmth. Since the epidermis is not involved, cellulitis is not transmitted by person-to-person contact.
Clinical presentation
Cellulitis can affect any region of the body, but mostand commonly affects thea lower limbs unilaterallylimb. Local featuresClinical presentations include skin erythema without a well-defined border, increased skin temperature, swelling of the affected area, and evidence of regional lymphadenopathy and lymphangitis. Additionally, systemic features such as fevers and rigors may also be present.
Complications
If the infection spreads to deeper tissues, complications and associated pathology can occur, e.g. such as soft-tissue abscess, infectious myositis, necrotising fasciitis, or osteomyelitis. Special consideration should be given to geriatric patients, in whom cellulitis of the lower extremities is more likely to develop into thrombophlebitis.
Pathology
Cellulitis occurs followingafter disruption of the skin and invasion of the subcutaneous tissues by microorganisms that may be indigenousskin flora, such as Staphylococcus aureus, or exogenousother bacteria. Patients with peripheral vascular disease or diabetes mellitus are particularly susceptible to this type of infectioncellulitis since minor injuries to the skin or cracked skin in the feet or toes can serve as a point of entry for infection.
Radiographic features
Ultrasound
Ultrasound is usually the first investigation to evaluate a clinical suspicion of cellulitis. Normally the subcutaneous tissue is hypoechoic with few hyperechoic strands (representing connective tissue). Above this, withthere is a narrow, relatively hyperechoic skin (epidermalepidermal-dermal) layer immediately superficial and. Muscular fascia lie deep to the fascia overlying muscle lying deepsubcutaneous layer.
- sonographic hallmarks of cellulitis include abnormal echogenicity and increased thickness of the
skindermis with indistinct "haziness" and increased echogenicity of the subcutaneous tissue-
it is often helpful to compare
sonographic appearancethe area in question toanalogous contralateral structuresthe (presumably normal) contralateral side
-
it is often helpful to compare
- progressive accumulation of oedema in the subcutaneous tissue appears as branching, anechoic striations which impart a lobulated ("cobble-stone" appearance "
- also present in other oedematous states
- presence of thickened and abnormally echogenic overlying skin will favor
cellulitic processcellulitis over edema - linear anechoic bands of fluid deep to the subcutaneous layer favor lymphoedema
CT
CT is used to accurately differentiate between superficial cellulitis and deep cellulitis (cellulitis associated with deep-seated infection).
In uncomplicated cellulitis, CT demonstrates skin thickening, septation of the subcutaneous fat, and thickening of the underlying superficial fascia. If the infection spreads to deeper tissues, deep cellulitis, soft-tissue abscess, infectious myositis, necrotising fasciitis, and osteomyelitis can all be detected with CT.
Treatment and prognosis
Uncomplicated cellulitis is a clinical diagnosis and isusually treated conservatively with antibiotics and locally supportive measures.
Differential diagnosis
Clinical differential diagnoses include:
- erysipelas
- deep vein thrombosis
- myriad of non-infective
,erythematous rashes
See also
-<p><strong>Cellulitis</strong> is an acute infection of the <a href="/articles/dermis">dermis</a> and subcutaneous tissues. It results in pain, erythema, oedema, and warmth. Since the <a href="/articles/epidermis">epidermis</a> is not involved, cellulitis is not transmitted by person-to-person contact.</p><h4>Clinical presentation</h4><p>Cellulitis can affect any region of the body, but most commonly affects the lower limbs unilaterally. Local features include skin erythema without a well-defined border, increased skin temperature, swelling of the affected area, and evidence of regional lymphadenopathy and lymphangitis. Additionally, systemic features such as fevers and rigors may also be present.</p><h5>Complications</h5><p>If the infection spreads to deeper tissues complications and associated pathology can occur, e.g. <a href="/articles/soft-tissue-abscess">soft-tissue abscess</a>, <a href="/articles/infectious-myositis">infectious myositis</a>, <a href="/articles/necrotizing-fasciitis">necrotising fasciitis</a>, or <a href="/articles/osteomyelitis">osteomyelitis</a>. Special consideration should be given to geriatric patients, in whom cellulitis of the lower extremities is more likely to develop into <a href="/articles/thrombophlebitis">thrombophlebitis</a>.</p><h4>Pathology</h4><p>Cellulitis occurs following disruption of the skin and invasion by microorganisms that may be indigenous flora, such as <em><a href="/articles/staphylococcus-aureus">Staphylococcus aureus</a></em>, or exogenous bacteria. Patients with <a href="/articles/peripheral-vascular-disease">peripheral vascular disease</a> or <a href="/articles/diabetes-mellitus">diabetes mellitus</a> are particularly susceptible to this type of infection since minor injuries to the skin or cracked skin in the feet or toes can serve as a point of entry for infection.</p><h4>Radiographic features</h4><h5>Ultrasound</h5><p>Ultrasound is usually the first investigation to evaluate a clinical suspicion of cellulitis. Normally the subcutaneous tissue is hypoechoic with few hyperechoic strands (representing connective tissue), with a narrow, relatively hyperechoic skin (epidermal-dermal) layer immediately superficial and the fascia overlying muscle lying deep. </p><ul>-<li>sonographic hallmarks include abnormal echogenicity and increased thickness of the skin with indistinct "haziness" and increased echogenicity of the subcutaneous tissue<ul><li>helpful to compare sonographic appearance to analogous contralateral structures</li></ul>- +<p><strong>Cellulitis</strong> is an acute infection of the <a href="/articles/dermis">dermis</a> and subcutaneous tissues. It results in pain, erythema, oedema, and warmth. Since the <a href="/articles/epidermis">epidermis</a> is not involved, cellulitis is not transmitted by person-to-person contact.</p><h4>Clinical presentation</h4><p>Cellulitis can affect any region of the body, and commonly affects a lower limb. Clinical presentations include skin erythema without a well-defined border, increased skin temperature, swelling of the affected area, and regional lymphadenopathy and lymphangitis. Additionally, systemic features such as fevers and rigors may also be present.</p><h5>Complications</h5><p>If the infection spreads to deeper tissues, complications can occur, such as <a href="/articles/soft-tissue-abscess">soft-tissue abscess</a>, <a href="/articles/infectious-myositis">infectious myositis</a>, <a href="/articles/necrotizing-fasciitis">necrotising fasciitis</a>, or <a href="/articles/osteomyelitis">osteomyelitis</a>. Special consideration should be given to geriatric patients, in whom cellulitis of the lower extremities is more likely to develop into <a href="/articles/thrombophlebitis">thrombophlebitis</a>.</p><h4>Pathology</h4><p>Cellulitis occurs after disruption of the skin and invasion of the subcutaneous tissues by microorganisms that may be skin flora, such as <em><a href="/articles/staphylococcus-aureus">Staphylococcus aureus</a></em>, or other bacteria. Patients with <a href="/articles/peripheral-vascular-disease">peripheral vascular disease</a> or <a href="/articles/diabetes-mellitus">diabetes mellitus</a> are particularly susceptible to cellulitis since minor injuries to the skin or cracked skin in the feet or toes can serve as a point of entry for infection.</p><h4>Radiographic features</h4><h5>Ultrasound</h5><p>Ultrasound is usually the first investigation to evaluate a clinical suspicion of cellulitis. Normally the subcutaneous tissue is hypoechoic with few hyperechoic strands (representing connective tissue). Above this, there is a narrow, relatively hyperechoic epidermal-dermal layer. Muscular fascia lie deep to the subcutaneous layer. </p><ul>
- +<li>sonographic hallmarks of cellulitis include abnormal echogenicity and increased thickness of the dermis with indistinct "haziness" and increased echogenicity of the subcutaneous tissue<ul><li>it is often helpful to compare the area in question to the (presumably normal) contralateral side</li></ul>
-<li>presence of thickened and abnormally echogenic overlying skin will favor cellulitic process</li>- +<li>presence of thickened and abnormally echogenic overlying skin will favor cellulitis over edema</li>
-</ul><h5>CT</h5><p>CT is used to accurately differentiate between superficial cellulitis and deep cellulitis (cellulitis associated with deep-seated infection). </p><p>In uncomplicated cellulitis, CT demonstrates skin thickening, septation of the <a href="/articles/subcutaneous-fat">subcutaneous fat</a>, and thickening of the underlying <a href="/articles/superficial-fascia">superficial fascia</a>. If the infection spreads to deeper tissues, deep cellulitis, soft-tissue abscess, infectious myositis, necrotising fasciitis, and osteomyelitis can all be detected with CT.</p><h4>Treatment and prognosis</h4><p>Uncomplicated cellulitis is a clinical diagnosis and is treated conservatively with antibiotics and locally supportive measures.</p><h4>Differential diagnosis</h4><p>Clinical differential diagnoses include:</p><ul>-<li><a title="erysipelas" href="/articles/erysipelas">erysipelas</a></li>-<li><a title="Deep vein thrombosis" href="/articles/deep-vein-thrombosis">deep vein thrombosis</a></li>-<li>myriad of non-infective, erythematous rashes </li>- +</ul><h5>CT</h5><p>CT is used to accurately differentiate between superficial cellulitis and deep cellulitis.</p><p>In uncomplicated cellulitis, CT demonstrates skin thickening, septation of the <a href="/articles/subcutaneous-fat">subcutaneous fat</a>, and thickening of the underlying <a href="/articles/superficial-fascia">superficial fascia</a>. If the infection spreads to deeper tissues, soft-tissue abscess, infectious myositis, necrotising fasciitis, and osteomyelitis can all be detected with CT.</p><h4>Treatment and prognosis</h4><p>Uncomplicated cellulitis is usually treated conservatively with antibiotics and locally supportive measures.</p><h4>Differential diagnosis</h4><p>Clinical differential diagnoses include:</p><ul>
- +<li><a href="/articles/erysipelas">erysipelas</a></li>
- +<li><a href="/articles/deep-vein-thrombosis">deep vein thrombosis</a></li>
- +<li>myriad of non-infective erythematous rashes </li>
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