Use of digital infrared imaging in the assessment of childhood psoriasis

Abstract

a chronic autoimmune diseasethat occurs when the immune system sendsout faulty signals that speed up the growthcycle of skin cells. It is well recognized that pso-riasis may have a markedly deleterious effecton the patient’s quality of life, with the physi-cal, social and psychological impact comparableto that seen in heart disease, diabetes mellitusand cancer (1). Psoriasis can affect children,approximately one-third of psoriasis patientsreport being diagnosed before being 20 yearsold (2). Self-esteem and behavior can be affectedby the disease and bullying has also been notedin clinical research (3).A wide variety of scoring systems have beenproposed to assess the severity of psoriasis;however, despite the importance of the evalua-tion of psoriasis there is a lack of consensus onthe most appropriate scoring system (4).The PASI (Psoriasis Area Severity Index)score is the most extensively studied clinicalseverity score for psoriasis and the most thor-oughly validated (4).In childhood and adolescence, the presence ofpsoriasis is associated with weight fluctuationsand an increased BMI, with poor cardiovascularprognosis (5). For this reason, it is difficult toassess the PASI, because the body surface area inchildhood and adolescence has larger variationsin short periods of time than the average adult.In this letter, thermal digital infrared imagingwas used to assess the progress and outcome ofan obese 9-year-old boy with psoriasis to objec-tively evaluate the affected area in a subjectwith significant surface area variations.The patient was a 9-year-old boy, obese(height 1.40 m, and weight 42.5 kg, both overthe 90th percentile), with a history of 4 yearswith a diagnosis of psoriasis and vitiligo treatedwith topical betamethasone as initial therapy,3 years after initial diagnosis a clinical worsen-ing of psoriatic lesions was observed and meth-otrexate was added to the treatment at a12.5 mg/week dose. No significant improve-ment was observed with treatment and thepatient maintained a PASI around 12.6 ± 2 for6 months. After a routine lab work was per-formed on the patient an infectious pyelonephri-tis was found, for that reason the methotrexatewas suspended and 50 mg of acitretin per daywas initiated and the psoriatic lesions weremonitored using digital infrared thermal imag-ing to evaluate the intensity of the lesions as thePASI alone gave significant variations due to thebody mass fluctuations observed on the patientduring the duration of treatment.Infrared imaging was performed using aFLIR T400 infrared camera (FLIR Systems, Wil-sonville, OR, USA) which has a 320 9 240 FocalPlane Array of uncooled microbolometers witha spectral range of 7.5–13 lm and a thermalsensitivity of 50 mK at 30°C.The thermographic analysis was performedusing FLIR QuickReport v1.2 (FLIR Systems,Wilsonville, OR, USA) which includes a tool toobtain maximum, minimum, and average tem-perature of a user-defined area.Before treatment the patient presented scat-tered lesions mostly around the right part ofthe chest and on the abdominal area (Fig. 1a),