Clinical REVIEW Cellulitis and lymphoedema: a vicious cycle Firas Al-Niaimi, Neil Cox Cellulitis is a relatively common infection of the skin and subcutaneous tissue associated with high morbidity and a burden on healthcare resources. Lymphoedema — the accumulation of fluid in interstitial spaces — can occur as a consequence of cellulitis. Similarly, the presence of chronic lymphoedema can predispose to recurrent episodes of cellulitis. This article explores the relationship between lymphoedema and cellulitis, with emphasis on diagnosis, management and methods of prevention. Symptoms of cellulitis vary depending tests have a relatively low diagnostic yield. Key words on the severity, which can range from Skin swabs for culture from intact skin mild to a more severe form with systemic are not helpful, but the yield of positive Cellulitis involvement in the form of tachycardia, results increases if a likely portal of Lymphoedema hypotension, and general malaise with a entry is present or if there is secondary Prophylactic therapy marked inflammatory response (Morton blistering (Dupuy et al, 1999; Tsao and PATCH and Swartz, 2004). A typical presentation Johnson, 1997). Swabs from erosions, is painful swelling with erythema that is exudate and ulcerations, if present, may hot and tender to touch, often preceded be more helpful (Tsao and Johnson, by ‘flu-like’ symptoms. Potential long- 1997). However, such lesions may have term consequences of cellulitis include secondary staphylococcal colonisation ellulitis is defined as an acute lymphoedema and leg ulceration and may not identify the primary cause, inflammation of the skin and (Cox, 2002). and swabs from pre-existing ulcers may Csubcutaneous tissue which is reveal several different bacteria. commonly caused by Streptococcus Various risk factors have been shown pyogenes or Staphylococcus aureus to be associated with cellulitis, with The main reason for the low rate (Morton and Swartz, 2004). The lower lymphoedema showing the strongest of identification of streptococci in leg is the most affected site, accounting association (Dupuy et al, 1999). This cellulitis is that the infection is of the for 75–90% of all cases (Tsao and is particularly the case in recurrent dermis, not of the skin surface, so it is Johnson, 1997). The true incidence of cellulitis. Streptococcal cellulitis associated difficult to identify. Another possible cellulitis is hard to estimate but a review with lymphoedema can be aggressive reason is that treatment has often of all hospital admissions in a UK district with severe symptoms and morbidity been initiated at an early stage and general hospital showed that about (Bonnetblanc and Bedane, 2003). may mask symptoms of fever, making 3% of all admissions were for cellulitis microbiological identification more (Morris, 2004), thereby constituting a Identifying cellulitis difficult. A review of 50 patients with huge financial burden on healthcare Cellulitis is often clinically apparent due cellulitis showed that only 26% had fever resources. The NHS Institute for to the presence of tender erythematous at the time of active cellulitis (Hook et Innovation and Improvement noted that swelling of the affected limb and al, 1986). A study performed by one of there were 45,522 inpatient admissions systemic symptoms of malaise (Morton the authors showed that 40% of patients for cellulitis in 2003–2004, costing the and Swartz, 2004). Fever and raised with cellulitis admitted to hospital were NHS £87m (Carter et al, 2007). inflammatory markers may also be apyrexial and systemically well (Cox et al, present. Blistering and ulceration occur in 1998). Hospital clinicians are aware that severe forms of cellulitis, often associated some patients are referred because they with marked oedema (Cox, 2002). are ‘not getting better’ despite antibiotic Firas Al-Niaimi is Specialist Registrar in Dermatology, Salford Various laboratory investigations have treatment, but this will often refer to Royal Hospital, Manchester, UK and Neil Cox is Consultant been used for diagnosis of cellulitis by redness or swelling which can persist for Dermatologist, Cumberland Infirmary, Carlisle, UK microbiological culture, but overall these some time after antibiotic treatment. 38 Journal of Lymphoedema, 2009, Vol 4, No 2 Cellulitis and lymph/BM.indd 14 25/9/09 11:46:47 Clinical REVIEW Blood cultures have been shown contribute to the reduction in morbidity in London involving 823 patients, 28% of to give a low yield for diagnosis in the as well as future recurrence (Collins et al, patients with lymphoedema had had an absence of bacteraemia. A retrospective 1989; Carter et al, 2007). episode of cellulitis within the previous 12 study among 757 patients with community- months (Moffatt et al, 2003). acquired cellulitis showed that only 2% of Risk factors for cellulitis patients had a significant patient-specific Local factors in the affected limb are Dupuy et al (1999) found that microbial strain isolated (Perl et al, 1999). strongly associated with a predisposition lymphoedema was present in 18% of A slightly higher rate of positive blood for cellulitis. General factors that might be their patients affected with cellulitis cultures in patients with leg lymphoedema regarded as risk factors include obesity, involving 167 patients with 294 controls. has been demonstrated (Baddour and smoking, alcohol misuse and diabetes A different study in which patients who Bisno, 1985). The authors believe that mellitus. The association with diabetes, had two or more episodes of leg cellulitis blood cultures have a marginal impact smoking and alcohol has not been proven were investigated with lymphoscintigraphy on clinical management in the absence in retrospective studies (Dupuy et al, 1999), (n=15) found significant lymphatic of systemic symptoms and raised but obesity has been shown to be linked abnormalities, suggesting a link with inflammatory markers, and therefore do with an increased risk (Scheinfeld, 2004). infective episodes (Soo et al, 2008). not appear to be cost-effective. This does Sixty percent of those patients also not however apply for necrotising fasciitis, Local factors causing defects in the skin had abnormal lymphoscintigrams in which is a more serious infection affecting barrier may increase the risk of developing the leg that had not been affected by the deeper tissue structures associated cellulitis by acting as a portal of entry for cellulitis, suggesting that pre-existing with high mortality and systemic sepsis. micro-organisms (Morton and Swartz, lymphatic abnormalities can precede the Although less common than cellulitis, 2004; Cox, 2002; Dupuy et al, 1999). Skin occurrence of clinical cellulitis. Stoberl necrotising fasciitis is often confused with trauma, lacerations, puncture wounds, leg et al (1987) found similar findings of cellulitis, particularly at its early phase of ulcers, dermatitis, toe web maceration abnormal lymphatic ducts among patients presentation where blood cultures have a and tinea pedis fall into this group. In a with cellulitis of the leg, and Damstra higher diagnostic yield (Cox, 2002). study involving 647 patients, 77% had local et al (2008) showed that 79% of 33 barrier defects that may have acted as patients with impaired lymph drainage Antistreptolysin titre (ASOT) levels portals of entry, 50% of which were fungal in the affected limb also had evidence of may confirm a streptococcal aetiology infections (mostly of the toe web) (Morris, impaired drainage in the unaffected limb. in retrospect, as this blood test result 2004). Among the aforementioned factors, is often raised as early as 7–10 days leg ulcers form the strongest risk (Dupuy These studies support the increasingly following a streptococcal infection, et al, 1999). accepted concept that previously and takes several weeks to subside undetected lymphatic abnormalities may (Cox, 2002; Eriksson et al, 1996). This Previous episodes of cellulitis be present among patients with cellulitis. investigation is particularly useful in are associated with a higher risk for Early detection of lymphatic abnormalities patients who are less likely to have a non- recurrence, possibly due to local soft through lymphoscintigraphy — the gold streptococcal aetiology (e.g. patients with tissue and lymphatic damage (de Godoy standard method for detecting lymphatic excoriated eczema, carbuncles, abscesses et al, 2000). This risk increases particularly abnormalities — and lymphoedema, or leg ulcers), as a negative test helps to if other factors are present (Bjoornsdottir and treatment of any abnormalities exclude a streptococcal cause. Conversely, et al, 2005). detected, may therefore reduce future confirming streptococcal infections can be episodes of cellulitis. However, there are useful when choosing antibiotic therapy A retrospective study among patients obvious practical limitations to this, as the for patients with recurrent cellulitis. with cellulitis who were followed for up abnormalities demonstrated are often to three years showed that 47% had a not easy to treat. Skin biopsy and/or aspirate have history of recurrent episodes (Cox, 2006). been shown to be of limited value in the Another study (n=233) showed that 29% Management of cellulitis diagnosis of cellulitis, but may have a role of patients had a recurrence within the The aim of treatment in cellulitis is in excluding some differential diagnoses first three years after their initial cellulitis resolution of the symptoms, reducing the such as vasculitis or eosinophilic