Dermis Health Dictionary

(1) Embryological tissue which has developed from the somites to become the dermis and subcutaneous tissue. The cutaneous area that is derived from each dermatome is supplied by a single dorsal spinal nerve root.

(2) A surgical instrument for removing very thin slices of skin for grafting.... dermatome

CONNECTIVE TISSUE which contains a profusion of yellow elastic ?bres. Long, slender and branching, these ?bres (made up of elastin, an albumin-like PROTEIN) ensure that the elastic tissue is ?exible and stretchable. The dermis layer of the skin, arterial walls and the alveolar walls in the LUNGS all contain elastic tissue.... elastic tissue

A thread-like structure composed of dead cells containing keratin, a fibrous protein. The root of each hair is embedded in a tiny pit in the dermis layer of the skin called a hair follicle. Each shaft of hair consists of a spongy semihollow core (the medulla), a surrounding layer of long, thin fibres (the cortex), and, on the outside, several layers of overlapping cells (the cuticle). While a hair is growing, the root is enclosed by tissue called a bulb, which supplies the hair with keratin. Once the hair has stopped growing, the bulb retracts from the root and the hair eventually falls out.

Hair is involved in the regulation of body temperature (known as thermoregulation). If the body is too cold, arrector pili muscles in the skin contract, pulling the hairs upright to form goose pimples. Erect hairs trap an insulating layer of air next to the skin.Brittle hair may be due to excessive styling, hypothyroidism, or severe vitamin or mineral deficiency. Very dry hair

can be caused by malnutrition. Ingrown hairs occur when the free-growing end of the hair penetrates the skin near the follicle, which may cause inflammation. (See also hirsutism; hypertrichosis.)... hair

Hard lumpy nodule of the skin due to overgrowth of ?brous tissue in the dermis. It usually follows surgical or accidental trauma or burns, but, rarely, may complicate acne on the upper trunk. Most commonly seen in the skin over the sternum, shoulders and upper back; coloured people are particularly prone. Injection of corticosteroid into the keloid may cause partial resolution. Excision should be avoided.... keloid

(1) A term used to describe the common pigmented spots which occur on human SKIN. It arises from a collection of abnormal melanocytes (see MELANOCYTE) in the dermis adjacent to the epidermodermal junction. Moles are usually not present at birth, and appear in childhood or adolescence. Most moles are less than 5 mm in diameter and are macular at ?rst, becoming raised later. Rarely, moles are present at birth and may occasionally be massive. There is a substantial risk of future malignancy (see MALIGNANT) in massive congenital moles and prophylactic surgical removal is advised if feasible. All humans have moles, but their number varies from ten or fewer to 100 or more. The members of some families are genetically predisposed to large numbers of moles, some of which may be large and irregular in shape and colour. This ‘atypical mole syndrome’ is associated with an increased risk of future malignant MELANOMA.

(2) An internationally agreed unit (see SI UNITS) for measuring the quantity of a substance at molecular level.... mole

Benign epithelial neoplasm in which neoplastic cells cover finger-like processes of dermis. Also anybenign epithelial neoplasm growing outward from an epithelial surface.... papilloma

Autoimmune disease of the SKIN in which the cells of the epidermis lose their adhesion to each other, resulting in blister formation.

Pemphigus vulgaris is a serious form affecting skin and MUCOUS MEMBRANE. It affects young and middle-aged people with widespread blistering, erosion and crusting of the skin. Extensive involvement of the lips, mouth and throat interfere with nutrition. Untreated, it is eventually fatal, but the disease can now be controlled by large doses of oral CORTICOSTEROIDS and other immunosuppressive drugs. MORBIDITY from the adverse effects of steroids is a serious problem, but some patients are eventually cured.

Pemphigus foliaceus is seen in the elderly; the blistering is more super?cial in the epidermis. It may be very widespread, but is not life-threatening because mucous membranes are not affected. Topical corticosteroids will sometimes control the eruption, but in severe cases treatment is as for pemphigus vulgaris.

Pemphigoid is a variant where the blistering occurs because of separation of the epidermis and dermis. Mucosae are rarely affected and the disease affects mainly the arms and legs in the elderly. Treatment is as for pemphigus but smaller doses of corticosteroids usually su?ce.... pemphigus

May attack those who face cold exposure as an occupational hazard, or who wear inadequate clothing in severe weather. Frost-nip of cheeks and chin. Dermis is frozen. May lead to Raynaud’s Disease, or long-term vein disease. Dullness of sensation.

Treatment: frozen limbs should not be rubbed or manipulated, but thawed out in luke-warm water, a hand still remaining in the glove or foot in the boot. Vasodilators to equalise the circulation.

Teas. Boneset, Chamomile, Elderflowers, Feverfew, Hyssop, Lime flowers, Peppermint, Sage, Gotu Kola, Yarrow. Buckwheat.

Echinacea: tablets, liquid extract, tinctures.

Never give alcohol or use hot water bottles. Paint with Friar’s balsam followed by smoothing-in a little Olive oil. Abundant Vitamin C drinks. Life Drops in tea. Ginger, Capsicum. Horseradish.

Old Norwegian remedy: cold mashed onion poultice.

Supplements. Hourly: Vitamin C 1g; Vitamin E 500iu. ... frostbite

Also called a stretch-mark, a line on the skin caused by thinning and loss of elasticity in the dermis. Striae first appear as red, raised lines. Later they become purple, eventually fading to shiny streaks.

Striae often develop on the hips and thighs during the adolescent growth spurt, especially in athletic girls. They are a common feature of pregnancy, occurring on the breasts, thighs, and lower abdomen. Purple striae are a characteristic feature of Cushing’s syndrome.

Striae are thought to be caused by an excess of corticosteroid hormones.

There is no means of prevention, but in some cases laser treatment may be used.... stria

the five vertical levels of skin that are successively penetrated by an invading *melanoma. They are: epidermis, papillary dermis, intervening zone, reticular dermis, and subcutaneous tissue. They usually correlate with the *Breslow thickness. [W. H. Clark (1924–97), US dermatologist]... clark’s levels

n. see dermis.... corium

adj. relating to or affecting the skin, especially the *dermis.... dermal

a projection of the dermis that is surrounded by the base of the hair bulb. It contains the capillaries that supply blood to the growing *hair.... hair papilla

adj. beneath the skin. A subcutaneous injection is given beneath the skin. Subcutaneous tissue is loose connective tissue, often fatty, situated under the dermis.... subcutaneous

They may be local to the SKIN, or a manifestation of systemic disorders – inherited or acquired. Some major types are described below.

Others appear under their appropriate alphabetical headings: ACNE; ALBINISM; ALOPECIA; ALOPECIA AREATA; APHTHOUS ULCER; BASAL CELL CARCINOMA; BOILS (FURUNCULOSIS); BOWEN’S DISEASE; CALLOSITIES; CANDIDA; CHEILOSIS; CHEIRAPOMPHOLYX; DANDRUFF; DERMATOFIBROMA; DERMATOMYOSITIS; DERMATOPHYTES; DERMOGRAPHISM; ECTHYMA; ERYSIPELAS; ERYTHEMA; ERYTHRASMA; ERYTHRODERMA; ESCHAR; EXANTHEM; FUNGAL AND YEAST INFECTIONS; HAND, FOOT AND MOUTH DISEASE; HERPES GENITALIS; HERPES SIMPLEX; HERPES ZOSTER; IMPETIGO; INTERTRIGO; KELOID; KERATOSIS; LARVA MIGRANS; LICHEN; LUPUS; MADURA FOOT; MELANOMA; MILIARIA; MOLLUSCUM CONTAGIOSUM; MOLE; MYCOSIS FUNGOIDES; NAEVUS; ORF; PEDICULOSIS; PEMPHIGUS; PHOTOCHEMOTHERAPY; PHOTODERMATOSES; PITYRIASIS; PORPHYRIAS; PRURITUS; PSORIASIS; RINGWORM; ROSACEA; SARCOIDOSIS; SCABIES; SCLERODERMA; URTICARIA; VITILIGO; WARTS; XANTHOMATA.

Skin cancer Primary cancer is common and chronic exposure to ultraviolet light is the most important cause. BASAL CELL CARCINOMA is the most common form; squamous cell carcinoma is less common and presents as a growing, usually painless nodule which may ulcerate. Squamous cancer may spread to regional lymph glands and metastasise, unlike basal cell cancer. Occupational exposure to chemical carcinogens may cause squamous carcinoma – for example, cancer from pitch warts or the scrotal carcinoma of chimney sweeps exposed to coal dust in earlier centuries. Squamous carcinoma of the lip is associated with clay-pipe smoking.

Cancer may arise from the population of melanocytes of the skin (see MELANOCYTE; MELANOMA).

Apart from these three most frequent forms of skin cancer, various forms of cancer can arise from cells of the dermis, of which LYMPHOMA is the most important (see also MYCOSIS FUNGOIDES).

Lastly, secondary deposits from internal cancer, particularly from the breast, may metastasise to the skin.

Dermatitis and eczema These are broadly synonymous, and the terms are frequently interchangeable. Eczema is a pattern of in?ammation with many potential causes. Dermatitis is commonly used to suggest an eczema caused by external factors; it is a common pattern of in?ammation of the skin characterised by redness and swelling, vesiculation (see VESICLE), and scaling with intense itching and often exudation (weeping). Fissuring, thickening (licheni?cation – see LICHEN) and secondary bacterial infection may follow. Dermatitis can affect any part of the body. It may be genetically detemined or due to other ‘internal’ factors, such as venous HYPERTENSION in a leg, or stress. Often it is ‘external’ in origin – due to strong irritants or chemical allergens. (See also ALLERGY; ALLERGEN.) ATOPIC DERMATITIS is genetic in origin and usually begins in infancy. It may persist for years, and ASTHMA, allergic RHINITIS and conjunctivitis (see under EYE, DISORDERS OF) – ‘hay fever’ – may be associated. Atopic children tend to have multiple allergies, especially to inhaled allergens such as house-dust mite, cat and dog dander and pollens. Allergy to foods is less common but potentially more dangerous, especially if to nuts, when it can cause acute URTICARIA or even ANAPHYLAXIS. Atopic subjects are particularly prone to persistent and multiple verrucae (see WARTS) and mollusca (see MOLLUSCUM CONTAGIOSUM) and to severe HERPES SIMPLEX infections. (See also ATOPY.)

EXFOLIATE DERMATITIS (PITYRIASIS RUBRA)

Generalised exfoliation and scaling of the skin, commonly with ERYTHEMA. Drugs may cause it, or the disorder may be linked with other skin diseases such as benign dermatoses and lupus erythematosus (see under LUPUS). SUMMER POMPHOLYX is an acute vesicular eczema of the palms and soles recurring every summer. Inhaled allergens are a frequent cause. VENOUS (STASIS) DERMATITIS begins on a lower calf, often in association with PURPURA, swelling and sometimes ulceration. Chronic venous hypertension in the leg, consequent on valvular incompetence in the deep leg veins owing to previous deep vein thrombosis (see VEINS, DISEASES OF), is the usual cause. NEURODERMATITIS A pattern of well-de?ned plaques of licheni?ed eczema particularly seen on the neck, ulnar forearms or sides of the calves in subjects under emotional stress. IRRITANT CONTACT DERMATITIS Most often seen in an industrial setting (occupational dermatitis), it is due to damage by strong chemicals such as cutting oils, cement, detergents and solvents. In almost all cases the hands are most severely affected. ALLERGIC CONTACT DERMATITIS, in contrast, can affect any part of the body depending on the cause – for example, the face (cosmetics), hands (plants, occupational allergens) or soles (rubber boots). Particularly common allergens include metals (nickel and chromate), rubber addititives, and adhesives (epoxy resins).

Treatment Avoidance of irritants and contact allergens, liberal use of EMOLLIENTS, and topical application of corticosteroid creams and ointments (see CORTICOSTEROIDS) are central.... skin, diseases of

a simple coiled tubular *exocrine gland that lies in the dermis of the *skin. A long duct carries its secretion (*sweat) to the surface of the skin. Sweat glands occur over most of the surface of the body; they are particularly abundant in the armpits, on the soles of the feet and palms of the hands, and on the forehead.... sweat gland

Tissue damage resulting from contact with heat, electricity, chemicals or radiation. Burns are classified according to the severity of damage to the skin. A 1st-degree burn causes reddening of the skin and affects only the epidermis, the top layer of the skin. A 2nd-degree burn damages the skin more deeply, extending into the dermis and causing blister formation. A 3rd-degree burn destroys the full skin thickness and may extend to the muscle layer beneath the skin. Specialist treatment, and possibly skin grafts, is necessary for 3rd-degree burns. Electrical burns can cause extensive tissue damage with minimal external skin damage. A 2ndor 3rd-degree burn that affects more than 10 per cent of the body surface causes shock due to massive fluid loss.

A burn is covered with a non-stick dressing to keep the area moist. If necessary, analgesic drugs are given, and antibiotic drugs are prescribed if there is any sign of infection. For extensive 2nddegree burns, when there may be slow healing or a fear of infection, a topical antibacterial agent such as silver sulphadiazine is used. Skin grafts are used early in treatment to minimize scarring. 3rd-degree burns always require skin grafting. Extensive burns may require repeated plastic surgery.... burns

The framework of bones that gives the body shape and provides attachment points for the muscles and underlying soft tissues of the body. The average human adult skeleton has 213 bones (counting each of the 9 fused vertebrae of the sacrum and coccyx as individual bones) joined with ligaments and tendons at points called joints. The skeleton plays an indispensable role inmovement by providing a strong, stable but mobile framework on which muscles can act. The skeleton also supports and protects internal body organs. skin The outermost covering of body tissue, which protects internal organs from the environment. Skin has 2 layers: the outer epidermis, and the inner dermis.

The outermost epidermis is composed of dead cells and the protein keratin. As these dead cells are worn away, they are replaced by new ones from the inner epidermis. Some epidermal cells produce the pigment melanin, which protects the body from ultraviolet light in sunlight.

The dermis is composed of connective tissue interspersed with hair follicles, sweat glands, sebaceous glands, blood and lymph vessels, and sensory receptors for pressure, temperature, and pain.... skeleton

n. tissue damage caused by such agents as heat, cold, chemicals, electricity, ultraviolet light, or nuclear radiation. A first-degree burn affects only the outer layer (epidermis) of the skin. In a second-degree burn both the epidermis and the underlying dermis are damaged. A third-degree burn involves damage or destruction of the skin to its full depth and damage to the tissues beneath. Burns cause swelling and blistering, due to loss of plasma from damaged blood vessels. In serious burns, affecting 15% or more of the body surface in adults (10% or more in children), this loss of plasma results in severe *shock and requires immediate transfusion of blood or saline solution. Burns may also lead to bacterial infection, which can be prevented by administration of antibiotics. Third-degree burns may require skin grafting. Small burns, or scars of previous burns, may be vital evidence of *child abuse.

burning mouth syndrome (BMS) a disorder characterized by a burning sensation in the mouth for which there is no obvious medical or dental cause. Other symptoms may include thirst, sore throat, and an unpleasant taste. BMS occurs most commonly in older females and may be related to menopause, stress, or vitamin deficiencies.... burn

n. flushing of the skin due to dilatation of the blood capillaries in the dermis. It may be physiological or a sign of inflammation or infection. Erythema nodosum is characterized by tender bruiselike swellings on the shins and is often associated with streptococcal infection. In erythema multiforme the eruption, which can take various forms, is characterized by so-called ‘target lesions’ that may be recurrent and follow herpes simplex infection (especially in children) or medications (especially in adults). Erythema ab igne is a reticular pigmented rash on the lower legs or elsewhere caused by persistent exposure to radiant heat. Erythema infectiosum (fifth disease, slapped cheek syndrome) is a common benign infectious disease of children caused by erythrovirus (human *parvovirus B19). It is characterized by fever and a rash, first on the cheeks and later on the trunk and extremities, that disappears after several days. Erythema toxicum neonatorum (neonatal urticaria) is a common self-limiting asymptomatic rash appearing in up to half of newborns, usually 2–5 days after birth. It is characterized by small erythematous papules and pustules surrounded by a diffuse blotchy erythematous halo. The eruption typically resolves within the first two weeks of life. See also palmar erythema. —erythematous adj.... erythema

n. the outer covering of the body, consisting of an outer layer, the *epidermis, and an inner layer, the *dermis (see illustration overleaf). Beneath the dermis is a layer of fatty tissue. The skin has several functions. The epidermis protects the body from injury and also from invasion by parasites. It also helps to prevent the body from becoming dehydrated. The combination of erectile hairs, *sweat glands, and blood capillaries in the skin form part of the temperature-regulating mechanism of the body. When the body is too hot, loss of heat is increased by sweating and by the dilation of the capillaries. When the body is too cold the sweat glands are inactive, the capillaries contract, and a layer of air is trapped over the epidermis by the erected hairs. The skin also acts as an organ of excretion (by the secretion of *sweat) and as a sense organ (it contains receptors that are sensitive to heat, cold, touch, and pain). The layer of fat that lies underneath the dermis can act as a reservoir of food and water. Anatomical name: cutis.... skin