There are many conditions of or affecting the human integumentary system

Integumentary system

The integumentary system is the organ system that protects the body from damage, comprising the skin and its appendages...

—the organ system that comprises the entire surface of the body

Human body

The human body is the entire structure of a human organism, and consists of a head, neck, torso, two arms and two legs.By the time the human reaches adulthood, the body consists of close to 100 trillion cells, the basic unit of life...

 and includes skin

Skin

-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

, hair

Hair

Hair is a filamentous biomaterial, that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class....

, nails

Nail (anatomy)

A nail is a horn-like envelope covering the dorsal aspect of the terminal phalanges of fingers and toes in humans, most non-human primates, and a few other mammals. Nails are similar to claws, which are found on numerous other animals....

, and related muscle

Muscle

Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

 and glands.

Diseases

Diseases of the skin include skin infection

Skin infection

A skin infection is an infection of the skin. Infection of the skin is distinguished from dermatitis, which is inflammation of the skin, but a skin infection can result in skin inflammation...

s and skin neoplasms (including skin cancer

Skin cancer

Skin neoplasms are skin growths with differing causes and varying degrees of malignancy. The three most common malignant skin cancers are basal cell cancer, squamous cell cancer, and melanoma, each of which is named after the type of skin cell from which it arises...

).

History

In 1572, Geronimo Mercuriali

Geronimo Mercuriali

Girolamo Mercuriale was an Italian philologist and physician, most famous for his work De Arte Gymnastica.-Biography:...

 of Forlì

Forlì

Forlì is a comune and city in Emilia-Romagna, Italy, and is the capital of the province of Forlì-Cesena. The city is situated along the Via Emilia, to the right of the Montone river, and is an important agricultural centre...

, Italy

Italy

Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

, completed De morbis cutaneis (translated "On the diseases of the skin"). It is considered the first scientific work dedicated to dermatology.

Epidemiology

In World War I, over two million days of service are estimated to have been lost by reason of skin diseases alone.

Approach to diagnoses

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. Most of these conditions present with cutaneous surface changes termed "lesions," which have more or less distinct characteristics. Often proper examination will lead the physician to obtain appropriate historical information and/or laboratory tests that are able to confirm the diagnosis. Upon examination, the important clinical observations are the (1) morphology, (2) configuration, and (3) distribution of the lesion(s). 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. Over time, these primary lesions may continue to develop or be modified by regression or trauma, producing "secondary lesions." 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. Nevertheless, there are some commonly accepted terms used to describe the macroscopic morphology, configuration, and distribution of skin lesions, which are listed below.

Primary lesions

• 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 10mm in diameter at the widest point.
• Patch - A patch is a large macule equal to or greater than either 5 or 10mm, 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.
• Papule
  Papule
  A papule is a circumscribed, solid elevation of skin with no visible fluid, varying in size from a pinhead to 1 cm.With regard to the quote "...varying in size from a pinhead to 1cm," depending on which text is referenced, some authors state the cutoff between a papule and a plaque as 0.5cm,...
  
  - A papule is a circumscribed, solid elevation of skin with no visible fluid, varying in size from a pinhead to either less than 5 or 10mm in diameter at the widest point.
• Plaque - A plaque has been described as a broad papule, or confluence of papules equal to or greater than 1 cm, or alternatively as an elevated, plateau-like lesion that is greater in its diameter than in its depth.Nodule - A nodule is morphologically similar to a papule, but is greater than either 5 or 10mm in both width and depth, and most frequently centered in the dermis or subcutaneous fat. The depth of involvement is what differentiates a nodule from a papule.
• Vesicle - A vesicle is a circumscribed, fluid-containing, epidermal elevation generally considered less than either 5 or 10mm in diameter at the widest point.
• Bulla - A bulla is a large vesicle described as a rounded or irregularly shaped blister containing serous or seropurulent fluid, equal to or greater than either 5 or 10mm, depending on one's definition of a vesicle.
• Pustule - A pustule is a small elevation of the skin containing cloudy or purulent material usually consisting of necrotic inflammatory cells. These can be either white or red.
• Cyst - A cyst is an epithelial-lined cavity containing liquid, semi-solid, or solid material.
• Erosion - An erosion is a discontinuity of the skin exhibiting incomplete loss of the epidermis, a lesion that is moist, circumscribed, and usually depressed.
• 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.
• Fissure
  Skin fissure
  A skin fissure is a cutaneous condition in which there is a linear-like cleavage of skin, sometimes defined as extending into the dermis. It is smaller than a skin laceration.-Generalized:...
  
  - A fissure is a crack in the skin that is usually narrow but deep.
• Wheal - A wheal is a rounded or flat-topped, pale red papule or plaque that is characteristically evanescent, disappearing within 24 to 48 hours.
• 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
  Keratin
  Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...
  
   that represent thickened stratum corneum.
• Crust - dried serum, pus, or blood usually mixed with epithelial and sometimes bacterial debris.
• Lichenification - epidermal thickening characterized by visible and palpable thickening of the skin with accentuated skin markings.
• Excoriation - a punctate or linear abrasion produced by mechanical means (often scratching), usually involving only the epidermis but not uncommonly reaching the papillary dermis.
• Induration - dermal thickening causing the cutaneous surface to feel thicker and firmer.
• 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.
• Maceration - softening and turning white of the skin due to being consistently wet.

Configuration

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

• Agminate
• Annular
• Arciform or arcuate
• Circinate
• Digitate
• Discoid
• Figurate
• Guttate
• Herpetiform
• Linear
• Nummular
• Mamillated
• Reticular or reticulated
• Serpiginous or gyrate
• Stellate
• Targetoid
• Verrucous

Distribution

"Distribution" refers to how lesions are localized. They may be confined to a single area (a patch) or may exist in several places. Several distributions correlate an anatomical reference. Some correlate with the means by which a given area becomes effected. For example, contact dermatitis correlates with locations where allergen has elicited an allergic immune response. Varicella Zoster Virus is known to recur (after its initial presentation as Chicken Pox) as Shingles. Chicken Pox appears nearly everywhere on the body but Shingles 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.)

• Generalized
• Symmetric (one side mirrors the other)
• Flexural (Front of the fingers)
• Extensor (back of the fingers)
• Intertriginous
• Morbilliform
• Palmoplantar (palm of the hand, bottom of the foot)
• Periorificial
• Periungual (under a finger or toe nail)
• Alopecia (hair loss)
• Blaschkoid
• Photodistributed (places where sunlight reaches)
• Zosteriform or dermatomal (associated with a particular nerve)

Other related terms:

• Collarette
• Comedo
  Blackhead
  A blackhead is a yellow or blackish bump or plug on the skin. A blackhead is a type of acne vulgaris. Contrary to the common belief that it is caused by poor hygiene, blackheads are caused by excess oils that have accumulated in the sebaceous gland's duct...
  
  
• Confluent
  Confluency
  In cell culture biology, confluency is the term commonly used as a measure of the number of the cells in a cell culture dish or a flask, and refers to the coverage of the dish or the flask by the cells...
  
  
• Eczema
  Eczema
  Eczema is a form of dermatitis, or inflammation of the epidermis . In England, an estimated 5.7 million or about one in every nine people have been diagnosed with the disease by a clinician at some point in their lives.The term eczema is broadly applied to a range of persistent skin conditions...
  
    (a type of dermatitis)
• Granuloma
  Granuloma
  Granuloma is a medical term for a tiny collection of immune cells known as macrophages. Granulomas form when the immune system attempts to wall off substances that it perceives as foreign but is unable to eliminate. Such substances include infectious organisms such as bacteria and fungi as well as...
  
  
• Livedo
  Livedo
  Livedo refers to a form of skin discoloration.* Livedo reticularis* Livedoid dermatitis* Livedoid vasculitis...
  
  
• Purpura
  Purpura
  Purpura is the appearance of red or purple discolorations on the skin that do not blanch on applying pressure. They are caused by bleeding underneath the skin...
  
  
• Erythema
  Erythema
  Erythema is redness of the skin, caused by hyperemia of the capillaries in the lower layers of the skin. It occurs with any skin injury, infection, or inflammation...
  
   (redness)
• Horn (a cell type)
• Poikiloderma
  Poikiloderma
  Poikiloderma is a skin condition that "consists of areas of increased and decreased pigmentation, prominent blood vessels, and thinning of the skin."...
  
  

Combined (conjoint) terms (maculopapular, papuloerosive, papulopustular, papulovesicular, papulosquamous, tuberoulcerative, vesiculobullous, vesiculopustular) are used to describe eruptions that evolve from one type of lesion to the next so often appear as having traits of both, when transitioning .

Histopathology

• Hyperkeratosis
  Hyperkeratosis
  Hyperkeratosis is thickening of the stratum corneum, often associated with a qualitative abnormality of the keratin, and also usually accompanied by an increase also in the granular layer...
  
  
• Parakeratosis
  Parakeratosis
  Parakeratosis is a mode of keratinization characterized by the retention of nuclei in the stratum corneum. Parakeratosis: The orderly but abnormal keratinisation of cells so that the keratin layer consists of plump nucleated keratinised cells instead of annular squames...
  
  
• Hypergranulosis
  Hypergranulosis
  Hypergranulosis is hyperplasia of the stratum granulosum, often due to intense rubbing....
  
  
• Acanthosis
  Acanthosis
  Acanthosis is diffuse epidermal hyperplasia.Acanthosis implies increased thickness of stratum spinosum. It is a disease ofthe prickle cell layer of the skin, where warts appear on the skin or inside the mouth.-References:...
  
  
• Papillomatosis
  Papillomatosis
  Papillomatosis is skin surface elevation caused by hyperplasia and enlargement of contiguous dermal papillae.- See also :* Skin lesion* Skin disease* List of skin diseases* Papilloma* Laryngeal papillomatosis...
  
  
• Dyskeratosis
  Dyskeratosis
  Dyskeratosis it is abnormal keratinization occurring prematurely within individual cells or groups of cells below the stratum corneum....
  
  
• Acantholysis
  Acantholysis
  Acantholysis is the loss of intercellular connections, such as desmosomes, resulting in loss of cohesion between keratinocytes, seen in diseases such as pemphigus vulgaris. It is absent in bullous pemphigoid, making it useful for differential diagnosis....
  
  
• Spongiosis
  Spongiosis
  Spongiosis is mainly intercellular edema between the keratinocytes in the epidermis, and is characteristic of eczematous dermatitis, manifested clinically by vesicles, "juicy" papules, and/or lichenification....
  
  
• Hydropic swelling
• Exocytosis
  Exocytosis (dermatopathology)
  Exocytosis is "infiltration of the epidermis by inflammatory or circulating blood cells."...
  
  
• Vacuolization
  Vacuolization
  Vacuolization is the formation of vacuoles within or adjacent to cells, and, in dermatopathology, often refers to the basal cell-basement membrane zone area....
  
  
• Erosion
• Ulceration
• Lentiginous
  Lentigo
  A lentigo is a small pigmented spot on the skin with a clearly-defined edge, surrounded by normal-appearing skin. It is a harmless hyperplasia of melanocytes which is linear in its spread. This means the hyperplasia of melanocytes is restricted to the cell layer directly above the basement...