The Red Leg Dilemma: A Scoping Review of the Challenges of Diagnosing Lower-limb Cellulitis

M. Patel; S.I. Lee; K.S. Thomas; J. Kai


The British Journal of Dermatology. 2019;180(5):993-1000. 

In This Article


This scoping review identified a lack of research on the challenges and facilitators in diagnosing lower-limb cellulitis. The existing literature on misdiagnoses is limited mainly to case reports and studies and was not always specific for lower-limb cellulitis. The 47 different misdiagnoses in case reports and series emphasize the wide differential diagnoses of cellulitis and how important it is to have diagnostic aids and other support to enable clinicians in different settings to make a correct diagnosis.

We found two examples of services developed in the U.K. to improve cellulitis diagnosis and care. One service showed that having cellulitis experts who are more likely to make a correct diagnosis of cellulitis can prevent inappropriate antibiotic use.[9] Another integrated 'red legs' service demonstrated how access to expert advice led to high patient satisfaction and economic savings.[75] This multidisciplinary approach may optimize correct diagnosis of red legs and merits further investigation.

Unfortunately, there is a lack of diagnostic aids for lower-limb cellulitis. Current aids have used biochemical tests or imaging, which may be unfeasible in some settings. All four studies were conducted in secondary care and have not been repeated prospectively. They did not compare cellulitis with the same differential diagnoses, which is required to improve the validity. Tests that differentiate cellulitis from only one other differential are useful only in very specific clinical presentations. A diagnostic aid to help rule in or rule out cellulitis in a red leg presentation is required.

The clinical cases of misdiagnosis highlight the everyday challenge faced by clinicians when diagnosing lower-limb cellulitis. Many patients with an alternative diagnosis can present with features that overlap with typical cellulitis. For primary-care physicians, who may see patients present with persistent symptoms despite antibiotic treatment, timely secondary-care advice or review should be considered prior to further antibiotic use.

Regarding the diagnostic aids, the ALT-70 model may be a quick tool that would be feasible in the hospital setting, but it is not practical in primary care where point-of-care blood tests cannot always be carried out in a timely way. It is also unlikely that computed tomography and MRI imaging would be used as a first-line investigation for cellulitis.

This scoping review has mapped out the available literature looking at the challenges in the diagnosis of lower-limb cellulitis. It is an important research priority topic that was proposed by patients and clinicians. The search terms were broad to capture all relevant papers, and two reviewers worked independently throughout screening and data extraction. Studies were included only if they discussed lower-limb cellulitis, and therefore this review can be applied to future lower-limb cellulitis research. However, papers that contained useful information were excluded if the site of cellulitis was not clear or if the results were not separated.

Due to the scoping nature of this review, only after the title and abstract screening stage was it apparent that themes were developing. Coding by a second reviewer would have been ideal, although the themes were discussed with all reviewers. Also, as the themes were developed after the initial search, the search terms used may not have allowed inclusion all of the papers for each theme.

Case reports and case series highlight rare pathologies, which explains why commonly seen diagnoses such as lymphoedema and eczema[9] were seldom reported. This scoping review is not intended to report the epidemiology of cellulitis misdiagnosis, which would be better addressed by observational studies or systematic reviews of prevalence studies. The clinical features described in the case reports and series, both prior to any treatment and when seen by the authors, were not always clearly separated. Nine foreign-text papers were translated, but it is possible that the information could still have been misinterpreted.

In conclusion, this scoping review highlights the current lack of evidence on diagnosis of lower-limb cellulitis, wide clinical diversity in its misdiagnosis and emerging approaches to service improvement and diagnostic aids. Further research to gain greater understanding of the challenges and facilitators in diagnosis of lower-limb cellulitis through qualitative research, involving patients and clinicians, is required.