tinea corporis

A patient presents with the skin lesions shown in the image above. The lesions are erythematous, annular, and scaly with central clearing. What is the most likely diagnosis?

A 25-year-old male gym instructor presents with a mildly pruritic, ring-shaped rash on his abdomen that has slowly expanded over 3 weeks. He shares locker-room towels and reports a similar rash in a training partner. He self-treated with topical corticosteroid for 10 days with worsening symptoms. Examination reveals the lesion marked **A** in the diagram—a 6 cm annular plaque with active raised erythematous scaly border and central clearing. KOH mount shows septate branching hyphae, and fungal culture grows *Trichophyton rubrum*. Which of the following is the most appropriate first-line treatment for this presentation?