4th August 2020

A 70-year-old man has been referred to dermatology for evaluation of an itchy skin rash

A 70-year-old man has been referred to dermatology for evaluation of an itchy skin rash. On examination, there is a well-demarcated area of exudative erythema over the gaiter region of his left leg; there is no evidence of ulceration, swelling, or tenderness; strong peripheral pulses are present bilaterally. He has recently finished active management for a venous ulcer over the same area. He is otherwise well. A couple of skin swabs have come back reporting no growth. How would you investigate this patient?

Select the SINGLE most appropriate investigation from the list below. Select ONE option only.