Layer of skin involved
The skin weighs an average of 4 kg (8.8 lb), covers an area of 2 m2 (22 sq ft), and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. The two main types of human skin are glabrous skin, the nonhairy skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. Within the latter type,  hairs in structures called pilosebaceous units have a hair follicle, sebaceous gland, and associated arrector pili muscle. In the embryo, the epidermis, hair, and glands are from the ectoderm, which is chemically influenced by the underlying mesoderm that forms the dermis and subcutaneous tissues. Epidermis
The epidermis is the most superficial layer of skin, a squamous epithelium with several strata: the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. Nourishment is provided to these layers via diffusion from the dermis, since the epidermis is without direct blood supply. The epidermis contains four cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells. Of these, keratinocytes are the major component, constituting roughly 95% of the epidermis. This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface.
Bulla: A bulla is a large blister, a rounded or irregularly shaped blister equal to or greater than either 5 or 10 mm, depending on ones definition of a vesicle. Pustule: A pustule is a small elevation of the skin usually consisting of necrotic inflammatory cells. Cyst: A cyst is an epithelial-lined cavity. Wheal: A wheal is a rounded or flat-topped, pale red papule or plaque that is characteristically evanescent, disappearing within 24 to 48 hours. The temporary raised skin on the site of a properly delivered intradermal (ID) injection is also called a welt, with the ID injection process itself frequently referred to as simply "raising a wheal" in medical texts. Welts: Welts occur as a result of blunt force being applied to the body with elongated objects without sharp edges. Telangiectasia: A telangiectasia represents an enlargement of superficial blood vessels to the point of being visible. Burrow: A burrow appears as a slightly elevated,  grayish, tortuous line in the skin, and is caused by burrowing organisms. Secondary lesions
Scale: Dry or greasy laminated masses of keratin, they represent thickened stratum corneum. Crust: Dried sebum usually mixed with epithelial and sometimes bacterial debris
Lichenification: Epidermal thickening characterized by visible and palpable thickening of the skin with accentuated skin markings
Erosion: An erosion is a discontinuity of the skin exhibiting incomplete loss of the epidermis, a lesion that is moist, circumscribed, and usually depressed.