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.