Skin condition

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"Pustule" redirects here. Skin condition_sentence_0

It is not to be confused with Boil. Skin condition_sentence_1

See also: List of cutaneous conditions Skin condition_sentence_2

Skin condition_table_infobox_0

Skin conditionSkin condition_header_cell_0_0_0
Other namesSkin condition_header_cell_0_1_0 Cutaneous conditionSkin condition_cell_0_1_1
SpecialtySkin condition_header_cell_0_2_0 DermatologySkin condition_cell_0_2_1

A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, hair, nails, and related muscle and glands. Skin condition_sentence_3

The major function of this system is as a barrier against the external environment. Skin condition_sentence_4

Conditions of the human integumentary system constitute a broad spectrum of diseases, also known as dermatoses, as well as many nonpathologic states (like, in certain circumstances, melanonychia and racquet nails). Skin condition_sentence_5

While only a small number of skin diseases account for most visits to the physician, thousands of skin conditions have been described. Skin condition_sentence_6

Classification of these conditions often presents many nosological challenges, since underlying causes and pathogenetics are often not known. Skin condition_sentence_7

Therefore, most current textbooks present a classification based on location (for example, conditions of the mucous membrane), morphology (chronic blistering conditions), cause (skin conditions resulting from physical factors), and so on. Skin condition_sentence_8

Clinically, the diagnosis of any particular skin condition is made by gathering pertinent information regarding the presenting skin lesion(s), including the location (such as arms, head, legs), symptoms (pruritus, pain), duration (acute or chronic), arrangement (solitary, generalized, annular, linear), morphology (macules, papules, vesicles), and color (red, blue, brown, black, white, yellow). Skin condition_sentence_9

The diagnosis of many conditions often also requires a skin biopsy which yields histologic information that can be correlated with the clinical presentation and any laboratory data. Skin condition_sentence_10

The introduction of cutaneous ultrasound has allowed the detection of cutaneous tumors, inflammatory processes, nail disorders and hair diseases. Skin condition_sentence_11

Layer of skin involved Skin condition_section_0

Main article: Integumentary system Skin condition_sentence_12

The skin weighs an average of 4 kg (8.8 lb), covers an area of 2 m (22 sq ft), and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. Skin condition_sentence_13

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. Skin condition_sentence_14

Within the latter type, hairs in structures called pilosebaceous units have a hair follicle, sebaceous gland, and associated arrector pili muscle. Skin condition_sentence_15

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. Skin condition_sentence_16

Epidermis Skin condition_section_1

Main article: Epidermis (skin) Skin condition_sentence_17

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. Skin condition_sentence_18

Nourishment is provided to these layers via diffusion from the dermis, since the epidermis is without direct blood supply. Skin condition_sentence_19

The epidermis contains four cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells. Skin condition_sentence_20

Of these, keratinocytes are the major component, constituting roughly 95% of the epidermis. Skin condition_sentence_21

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. Skin condition_sentence_22

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. Skin condition_sentence_23

Dermis Skin condition_section_2

Main article: Dermis Skin condition_sentence_24

The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary dermis and the reticular dermis. Skin condition_sentence_25

The superficial papillary dermis with the overlying rete ridges of the epidermis, between which the two layers interact through the basement membrane zone. Skin condition_sentence_26

Structural components of the dermis are collagen, elastic fibers, and ground substance also called extra fibrillar matrix. Skin condition_sentence_27

Within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands. Skin condition_sentence_28

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. Skin condition_sentence_29

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. Skin condition_sentence_30

Subcutaneous tissue Skin condition_section_3

Main article: Subcutaneous tissue Skin condition_sentence_31

The subcutaneous tissue is a layer of fat between the dermis and underlying fascia. Skin condition_sentence_32

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. Skin condition_sentence_33

The main cellular component of this tissue is the adipocyte, or fat cell. Skin condition_sentence_34

The structure of this tissue is composed of septal (i.e. linear strands) and lobular compartments, which differ in microscopic appearance. Skin condition_sentence_35

Functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source. Skin condition_sentence_36

Diseases of the skin Skin condition_section_4

For a comprehensive list, see List of cutaneous conditions. Skin condition_sentence_37

Diseases of the skin include skin infections and skin neoplasms (including skin cancer). Skin condition_sentence_38

History Skin condition_section_5

See also: History of dermatology Skin condition_sentence_39

In 1572, Geronimo Mercuriali of Forlì, Italy, completed De morbis cutaneis ('On the diseases of the skin'). Skin condition_sentence_40

It is considered the first scientific work dedicated to dermatology. Skin condition_sentence_41

Diagnoses Skin condition_section_6

The physical examination of the skin and its appendages, as well as the mucous membranes, forms the cornerstone of an accurate diagnosis of cutaneous conditions. Skin condition_sentence_42

Most of these conditions present with cutaneous surface changes termed "lesions," which have more or less distinct characteristics. Skin condition_sentence_43

Often proper examination will lead the physician to obtain appropriate historical information and/or laboratory tests that are able to confirm the diagnosis. Skin condition_sentence_44

Upon examination, the important clinical observations are the (1) morphology, (2) configuration, and (3) distribution of the lesion(s). Skin condition_sentence_45

With regard to morphology, the initial lesion that characterizes a condition is known as the "primary lesion", and identification of such a lesions is the most important aspect of the cutaneous examination. Skin condition_sentence_46

Over time, these primary lesions may continue to develop or be modified by regression or trauma, producing "secondary lesions". Skin condition_sentence_47

However, with that being stated, the lack of standardization of basic dermatologic terminology has been one of the principal barriers to successful communication among physicians in describing cutaneous findings. Skin condition_sentence_48

Nevertheless, there are some commonly accepted terms used to describe the macroscopic morphology, configuration, and distribution of skin lesions, which are listed below. Skin condition_sentence_49

Lesions Skin condition_section_7

Primary lesions Skin condition_section_8

Skin condition_unordered_list_0

  • Macule: A macule is a change in surface color, without elevation or depression and, therefore, nonpalpable, well or ill-defined, variously sized, but generally considered less than either 5 or 10 mm in diameter at the widest point.Skin condition_item_0_0
  • Patch: A patch is a large macule equal to or greater than either 5 or 10 mm across, depending on one's definition of a macule. Patches may have some subtle surface change, such as a fine scale or wrinkling, but although the consistency of the surface is changed, the lesion itself is not palpable.Skin condition_item_0_1
  • Papule: A papule is a circumscribed, solid elevation of skin with no visible fluid, varying in size from a pinhead to less than either 5 or 10 mm in diameter at the widest point.Skin condition_item_0_2
  • Plaque: A plaque has been described as a broad papule, or confluence of papules equal to or greater than 10 mm, or alternatively as an elevated, plateau-like lesion that is greater in its diameter than in its depth.Skin condition_item_0_3
  • Nodule: A nodule is morphologically similar to a papule in that it is also a palpable spherical lesion less than 10 mm in diameter. However, it is differentiated by being centered deeper in the dermis or subcutis.Skin condition_item_0_4
  • Tumour: Similar to a nodule but larger than 10 mm in diameter.Skin condition_item_0_5
  • Vesicle: A vesicle is small blister, a circumscribed, fluid-containing, epidermal elevation generally considered less than either 5 or 10 mm in diameter at the widest point. The fluid is clear serous fluid.Skin condition_item_0_6
  • Bulla: A bulla is a large blister, a rounded or irregularly shaped blister containing serous or seropurulent fluid, equal to or greater than either 5 or 10 mm, depending on one's definition of a vesicle.Skin condition_item_0_7
  • Pustule: A pustule is a small elevation of the skin containing cloudy or purulent material (pus) usually consisting of necrotic inflammatory cells. These can be either white or red.Skin condition_item_0_8
  • Cyst: A cyst is an epithelial-lined cavity containing liquid, semi-solid, or solid material.Skin condition_item_0_9

Skin condition_unordered_list_1

  • Skin condition_item_1_10

Skin condition_unordered_list_2

  • 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 bubble of taut skin on the site of a properly-delivered intradermal injection is also called a welt, with the ID injection process itself frequently referred to as simply "raising a wheal" in medical texts.Skin condition_item_2_11
  • Telangiectasia: A telangiectasia represents an enlargement of superficial blood vessels to the point of being visible.Skin condition_item_2_12
  • Burrow: A burrow appears as a slightly elevated, grayish, tortuous line in the skin, and is caused by burrowing organisms.Skin condition_item_2_13

Secondary lesions Skin condition_section_9

Skin condition_unordered_list_3

  • Scale: dry or greasy laminated masses of keratin that represent thickened stratum corneum.Skin condition_item_3_14
  • Crust: dried sebum, pus, or blood usually mixed with epithelial and sometimes bacterial debris.Skin condition_item_3_15
  • Lichenification: epidermal thickening characterized by visible and palpable thickening of the skin with accentuated skin markings.Skin condition_item_3_16
  • Erosion: An erosion is a discontinuity of the skin exhibiting incomplete loss of the epidermis, a lesion that is moist, circumscribed, and usually depressed.Skin condition_item_3_17
  • Excoriation: a punctate or linear abrasion produced by mechanical means (often scratching), usually involving only the epidermis, but commonly reaching the papillary dermis.Skin condition_item_3_18
  • Ulcer: An ulcer is a discontinuity of the skin exhibiting complete loss of the epidermis and often portions of the dermis and even subcutaneous fat.Skin condition_item_3_19
  • Fissure: A fissure is a crack in the skin that is usually narrow but deep.Skin condition_item_3_20
  • Induration: dermal thickening causing the cutaneous surface to feel thicker and firmer.Skin condition_item_3_21
  • Atrophy: refers to a loss of tissue, and can be epidermal, dermal, or subcutaneous. With epidermal atrophy, the skin appears thin, translucent, and wrinkled. Dermal or subcutaneous atrophy is represented by depression of the skin.Skin condition_item_3_22
  • Maceration: softening and turning white of the skin due to being consistently wet.Skin condition_item_3_23
  • Umbilication: formation of a depression at the top of a papule, vesicle, or pustule.Skin condition_item_3_24
  • : A tubercle on any external part of the body, such as in phymatous rosaceaSkin condition_item_3_25

Configuration Skin condition_section_10

"Configuration" refers to how lesions are locally grouped ("organized"), which contrasts with how they are distributed (see next section). Skin condition_sentence_50

Distribution Skin condition_section_11

"Distribution" refers to how lesions are localized. Skin condition_sentence_51

They may be confined to a single area (a patch) or may exist in several places. Skin condition_sentence_52

Some distributions correlate with the means by which a given area becomes affected. Skin condition_sentence_53

For example, contact dermatitis correlates with locations where allergen has elicited an allergic immune response. Skin condition_sentence_54

Varicella zoster virus is known to recur (after its initial presentation as chicken pox) as herpes zoster ("shingles"). Skin condition_sentence_55

Chicken pox appears nearly everywhere on the body, but herpes zoster tends to follow one or two dermatomes; for example, the eruptions may appear along the bra line, on either or both sides of the patient. Skin condition_sentence_56

Other related terms Skin condition_section_12

Histopathology Skin condition_section_13

Credits to the contents of this page go to the authors of the corresponding Wikipedia page: condition.