An asymptomatic erythematous scaly plaque on the left lower back

A 61-year-old man was referred to our dermatology department for the evaluation of a single asymptomatic plaque on his left lower back that has been present for one year. the lesion began as an erythematous scaly plaque that slowly increased in size; he had been treated with topical antifungals and topical corticosteroid without any improvement. clinical examination revealed a solitary erythematous scaly plaque measuring 2.5×5 cm in diameter. a blanchable annular erythema encircled the psoriasis-like plaque but separated from the plaque by a rim of normal appearing skin (figure1). he had no other cutaneous lesions. the regional lymph nodes were not palpable and no hepatosplenomegaly was detected; the patient was otherwise in good health. the patient was not taking any medications.