How would you diagnose his pigmented eruptions?

Answer—Disseminated superficial actinic porokeratoses

This patient had a hyperpigmented variant of disseminated superficial actinic porokeratosis. This hereditary condition is typically found on the sun-exposed portions of extremities. It can be asymptomatic or slightly itchy. Note: Of concern are reports of squamous cell carcinoma and rarely basal cell carcinoma arising from these lesions.

The lesions are characterized by a distinct thin keratotic border, which can be seen and felt. Stasis dermatitis would not expect to have discrete lesions. Diabetic dermopathy is usually atrophic in the setting of diabetes mellitus. Seborrheic keratoses look similar on cursory exam, but can be distinguished clinically with magnification. Pigmented purpura should show evidence of petechiae on exam.