Detecting and quantifying activity/inflammation in localized scleroderma with thermal imaging

Background The disease phase in localized scleroderma (LoS) is commonly assessed by clinical investigation using the LoS cutaneous assessment tool (LoSCAT). There is a need for more objective methods for assessing the degree of activity/inflammation in LoS. The aim of our work was to evaluate the correlation between severity of the LoS lesions scored using LoSCAT and the degree of hyperthermia observed with infrared thermography (IRT). Materials and methods The LoS lesions were examined using the LoSCAT and IRT independently by two examiners. The average temperature (Tavg) of the LoS lesional dermis were measured in the area of each lesion with the highest score for erythema (ER), skin thickness (ST), dermal atrophy (DAT) and subcutaneous atrophy (SAT). Measurements were compared to the contralateral healthy skin. The difference of the Tavg (Delta Tavg) was calculated between each lesion and its normal control. Results One hundred and four LoS lesions were examined in 40 adults. Thirty-one lesions were erythematous, 26 were sclerotic, 35 presented as atrophy of the dermis and 11 as atrophy of the subcutaneous tissue. The sensitivity and specificity of IRT for detecting activity/inflammation were 80.7% and 86.3%, respectively. The positive predictive value was 71%, negative predictive value 91%. Statistically significant positive correlation was found between the Delta Tavg and the clinical ER and DAT scores. Conclusion IRT may be a useful method for assessing erythematous LoS lesions and quantifying the degree of activity/inflammation. Knowing the patient, false positive results attributable to more severe degree of skin and subcutaneous fat atrophy can be easily recognized.