Complaints of rash, burni...

An 82-year-old male presented to the clinic with complaints of rash, burning, and itching on both knees. The patient has an H/o gonarthrotic. He had applied M. Radix sap to his knees for arthralgia for three consecutive days, and the lesions appeared on the fourth day. Dermatological findings were normal except for erythematous, oedematous, and scaly plaque lesions, as shown in the figure. In addition, an open application test (OAT) was performed on a 1 cm2 area of skin on the patient’s upper arm, as shown in the figure