Derm Dx: Erythematous, indurated, follicular dermatitis on the shin

A 45-year-old woman presents with an itchy rash on her right leg. Her medical history is significant for type 2 diabetes controlled with glucophage. On physical examination, the right anterior shin exhibits an erythematous, indurated, follicular dermatitis. An annular, erythematous scaly patch with central clearing is noted below the knee.