Secondary Skin Lesions Pruritus Primary Skin Lesions Primary lesions are early skin changes that have not yet undergone natural evolution or change caused by manipulation. These are the best clues to diagnosis. Examples include freckles, flat moles, tattoos, port-wine stains, and the rashes of rickettsial infections, rubella, measles, and some allergic drug eruptions. Examples include warts, some nevi, psoriasis, syphilitic chancre, lichen planus, some drug eruptions, insect bites, seborrheic and actinic keratoses, some lesions of acne, and skin cancers. Examples include keratinous cysts, small lipomas, fibromas, erythema nodosum, and some lymphomas and other neoplasms.
Pustules are superficial and elevated lesions containing pus.
They may result from infection or seropurulent evolution of vesicles or bullae. Some causes are impetigo, acne, folliculitis, furuncles, carbuncles, certain deep fungus infections, hidradenitis suppurativa, kerion, pustular miliaria, and pustular psoriasis of the palms and soles. Wheals are a common allergic reaction, eg, from drug eruptions, insect stings or bites, or sensitivity to cold, heat, pressure, or sunlight. Larger localized areas of edema in the subcutis are called angioneurotic edema. Purpura is a general term referring to areas of extravasated blood.