A 13 years, boy c/o rash on lt leg since 6 years, not responding to treatment of dermatologist. Lately his TSH 9.56, Aslo titre 1210, ESR 60 are found high. Other tests like CRP LFT CBC, HBA1C are found normal. Pt is robust ,no problem, only mother worried.

On repeat test in another lab again same result was seen. What can be the possible cause of the rash? Is it erythema marginatum, or just a residual symptom of rheumatic fever in children?