One of the most typical clinical and biophysical characteristics of skin and soft tissue infections is increased temperature1. However, these differences in heat can sometimes be difficult to identify on clinical examination and doubts can arise about how the disease is progressing.
We present the case of a 54-year-old woman, with no history of interest, who went to the Dermatology A&E department with a painful lumbar lesion of several days' duration, accompanied by fever. On examination, an erythematous, hot and indurated plaque was observed in the lumbar region and mid-upper gluteal region, diagnosed as a skin and soft tissue infection or infectious cellulitis. As a portal of entry, an ulcerated, pearly, shiny plaque was seen in the intergluteal fold, consistent with genital lichen sclerosus. A smear was taken from the intergluteal fold, in which Gram-positive mixed flora was found. As treatment, a cycle of amoxicillin-clavulanate 875 mg/125 mg orally every 8 h for 7 days was prescribed, potentiated with topical ozenoxacin and fluticasone in combination to be applied to the intergluteal area, with resolution of the symptoms.
At the time of diagnosis, a thermographic image was taken with a FLIR camera adaptable to an iOS device. In the image, a temperature difference of 2.55 °C was observed between the affected and perilesional skin, with follow-up images taken on days 2 and 7 of therapy revealing a decrease in this temperature difference (2.49 °C and 0.66 °C, respectively) until it was practically equal to healthy skin (Fig. 1). It can be seen that the response to antibiotic therapy was notable from the first day and the changes could be clearly visualised in the thermographic image.
Thermography is a non-invasive imaging technique that makes it possible to establish temperature differences by analysing the infrared radiation emitted by the skin, which correlates with its temperature and facilitates the assessment of subclinical inflammation2. Its most widespread medical use has been for fever screening during the COVID-19 pandemic3. In the field of infectious diseases, it has been used to screen for tinea unguium, to predict residual neuralgia in herpes zoster or to assess pressure ulcers4–6.
It is a simple and cheap technique that can be carried out with devices that can be adapted to mobile phones. The results, which are visible on a colour map with zones that correspond to hotter areas and others to colder areas, are easy and intuitive to interpret7. Focusing on the subject at hand, innovative data have recently been published on the potential use of this technique to establish the differential diagnosis between cellulitis and pseudocellulitis, yielding a sensitivity of up to 95.2%8. However, to our knowledge, this is the first case in which it has been used for the clinical follow-up of this condition, to determine the response to treatment. More extensive studies are required.
In conclusion, thermography is an imaging technique that is simple to perform during a consultation and is easy and intuitive to interpret, with potential application in the field of infectious diseases for the diagnosis and follow-up of skin and soft tissue infections by detecting subtle changes in temperature.
Ethical considerationsThe patients gave their informed consent for the publication of the images from this study.
FundingThis study did not receive any type of funding.
Conflicts of interestThe authors declare that they have no conflicts of interest.
