A 45-Year-Old With Multiple Skin Lesions on Sun-Protected Areas of the Body

A patient had multiple erythematous macules and patches on the trunk, hyperpigmented patches on the intergluteal cleft and subgluteal fold, and poikiloderma in the axillae; results of laboratory testing, including antinuclear antibody test, were unremarkable. What is the diagnosis and what would you do next?