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.
In normal skin, the rate of production equals the rate of loss; about two weeks are needed for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum. Dermis
The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary dermis and the reticular dermis. The superficial papillary dermis interdigitates with the overlying rete ridges of the epidermis, between which the two layers interact through the basement membrane zone. Structural components of the dermis are collagen, elastic fibers, and ground substance also called extra fibrillar matrix. Within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands. The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels. The function of blood vessels within the dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing. Subcutaneous tissue
The subcutaneous tissue is a layer of fat between the dermis and underlying fascia. This tissue may be further divided into two components, the actual fatty layer, or panniculus adiposus, and a deeper vestigial layer of muscle, the panniculus carnosus. The main cellular component of this tissue is the adipocyte, or fat cell. The structure of this tissue is composed of septal (i.e. linear strands) and lobular compartments, which differ in microscopic appearance.