To avoid missing serious causes,<unk>  must be approached systemically.
Primarily, the decision as to whether lesions are focal or diffuse is made, lesion history is taken, system review, and a focused physical exam. Non obvious lesions should be referred to a dermatologist.
Vesicular and bullous lesions
Pigmented lesions
Janeway lesions
Stasis dermatitis and ulcers
Mucopurulent discharge
Papulosquamous lesions
Hyperpigmentation
Nodular lesions