An abscess is a localised collection of pus.
Acne is another term for a blemish or a pimple that occurs in the skin. It is usually more prevalent in oily skin. Severe acne causes cysts and infected abscesses. Individuals experiencing severe acne may be helped by a dermatologist.
Acral distribution of a dermatosis means it affects distal portions of limbs (hand, foot) and head (ears, nose).
Adipose cells or lipocytes are grroups of fat cells forming yellow lobules in subcutaneous tissue.
“Adolescence” refers to the physiological transition from childhood to adulthood. Adolescence ranges roughly from 11-18 years of age. Hormonal changes that occur during adolescence can cause oil glands in the skin to become overactive, and become prone to breakouts.
Testing conducted on ARTISTRY products to ensure that the products do not cause new allergic reactions in customers. The tests are conducted by independent third party clinical laboratories.
Anagen is the growth phase of the hair cycle. Anagen hair has a pointed tip and grows over several years.
Annular distribution refers to lesions grouped in a circle.
Antioxidants help to neutralize the free radicals that cause skin aging.
Aplasia refers to tissue that has failed to grow, as in aplasia cutis (illustrated).
Apocrine glands are scent glands found most profusely in armpits and groins. They become active after puberty. Apocrine sweat is thick and odourless; the smell derives from bacterial colonisation.
The epidermal appendages include eccrine (sweat) glands, apocrine (scent) glands, pilosebaceous structures (hair and oil glands) and nails.
Arrector pili muscles originate near the basement membrane zone and attach to the hair follicle near its base. They cause erection of the hairs on exposure to cold or fear (goose bumps).
Commonly known as toner, it controls oily skin and lowers the pH of the face after cleansing. Basically it draws tissues together.
Atrophy occurs when some component of the skin has shrunk.
A paper-thin layer at the top of the epidermis that provides the skin’s protective functions. It is referred as the stratum corneum.
The basal layer is the columnar or rectangular cells at the bottom of the epidermis from which new cells are continuously produced. Scattered melanocytes are normally found in this layer.
The basement membrane zone separates the epidermis from the dermis. Its components include the selectively permeable basal cell membrane, lamina lucida containing anchoring filaments, lamina densa and sublamina densa (bound to the dermis).
Blaschko lines follow a roughly linear, segmental pattern described by Blaschko. Many birthmarks appear to be distributed within these segments.
Pimples that occur in the skin.
The capillaries are the smallest blood vessels you can find in your body. Their job is to distribute nutrients and oxygenated blood to the tissues of your body, and remove deoxygenated blood and cellular waste from the tissues back into the veins.
Booster products provide special care for the skin by targeting specific concerns.
Broad-spectrum sunscreens contain ingredients that protect against 2 types of UV radiation: UVA rays and UVB rays. UVB rays are shorter rays that are known to burn the skin while UVA rays are longer rays that can penetrate deeper and lead to premature aging of the skin. It is imperative to protect your skin from both UVA and UVB rays.
This means that protection against both UVA & UVB radiation.
A bulla is a large fluid-filled blister greater than 1 cm in diameter. It may be a single compartment or multiloculated. The adjective is ‘bullous’.
Carcinoma refers to cancer made up of malignant epithelial cells (e.g. basal cell carcinoma, illustrated).
Catagen is a short involutional phase of the hair cycle.
The process by which skin cells are born at the base of the epidermis and slowly move upward until they form a paper-thin barrier at the top of the epidermis. This indispensable new barrier guards against moisture loss and environmental damage.
Collagen is the structural protein making up the bulk of the dermis. It is produced by fibroblasts. It is composed of a triple helix of strong fibres.
Configuration refers to the shape or outline of the skin lesions. Skin lesions are often grouped together. The pattern or shape may help in diagnosis as many skin conditions have characteristic configuration.
Connective tissue of the skin refers to dermis and subcutaneous tissue.
Crust occurs when plasma exudes through an eroded epidermis and dries on the skin surface. It is rough on the surface and is yellow or brown in colour. Bloody crust appears red, purple or black.
A cyst is a papule or nodule that contains fluid or semi-fluid material so is fluctuant.
Dendritic cells are cells with long finger-like processes (dendrites), and include melanocytes, Langerhans cells and some tissue macrophages (immune cells).
The medical specialist in diseases of skin, hair and nails. Refer to DermNet's pages, What is a Dermatologist.
The study of skin, hair and nails.
Corresponding with nerve root distribution (dermatome), as seen with the blistering rash herpes zoster (shingles, illustrated).
Dermatosis is another name for for skin disease.
The dermis is the middle connective tissue layer of skin, composed of collagen and elastin fibres, blood vessels, nerves and inflammatory cells in a ground substance gel.
Desmosomes are the structures that stick adjacent keratinocytes tightly together, rather like cement between bricks.
Desquamation is the term given to skin coming off in scales or peeling.
The distribution of a dermatosis refers to how the skin lesions are scattered or spread out. Skin lesions may be isolated (solitary or single) or multiple. The localisation of multiple lesions in certain regions helps diagnosis, as skin diseases tend to have characteristic distributions.
Dysplasia means abnormal development of a cell or tissue. ‘Dysplastic naevi’ are atypical moles (illustrated), and are variously defined.
Dystrophy refers to degeneration or abnormal formation of the skin. It is often used to refer to nail diseases.
Ecchymoses are bruises.
Eccrine glands are found deep in the dermis. They produce sweat, a weak solution of water, salt and waste products, which is excreted into a coiled duct that opens directly onto the skin surface. They are most dense on palms, soles, armpits and forehead. Excessive sweating is known ashyperhidrosis.
Elastin is the protein making up thin elastic fibres. These are produced by fibroblasts. They return deformed skin to its resting position.
The epidermis is the outer epithelial layer of the skin, and is mainly composed of keratinocytes.
Epithelium is a tissue composed of packed cells that line a body surface internally (e.g. mouth) or externally (e.g. skin).
Erosion is caused by loss of the surface (epidermis) of a skin lesion; it is a shallow moist or crusted lesion.
Erythema is the name given to red skin due to increased blood supply and may be applied to any red coloured dermatosis.
Erythroderma occurs when a skin condition affects the whole body or nearly the whole body, which is red all over.
Dark-coloured adherent crust of dead tissue found on some ulcers.
An excoriation is a scratch mark or surface injury penetrating the dermis. It may be linear or a picked scratch (prurigo). Excoriations may occur in the absence of a primary dermatosis.
Exfoliation refers to peeling skin.
Extensor distribution of a dermatosis involves the extensor surfaces of limbs, i.e. the outer arm or the front of the leg, as is often the case with psoriasis.
A felon is an abscess in the pulp of any digit.
Fibroblasts are cells found in the dermis that produce collagen, elastin, ground substance and fibronectin (a glycoprotein).
Filiform means thread-like as in ‘filiform wart’.
A fissure is a thin crack within epidermis or epithelium, and is due to excessive dryness.
Flexural distribution of a dermatosis involves the flexures, i.e. the body folds. This is also known as intertriginous distribution.
Follicular distribution of a dermatosis refers to individual lesions arisin from hair follicles, e.g. acne. These may be grouped into confluent plaques.
Refers to a large malignant tumour that is erupting like a mushroom or fungus.
Description of scale in which is is bran-like or powdery.
The granular layer of the epidermis (stratum granulosum) is characterised by flattened cells filled with dark granules containing keratohyaline protein.
Granulation tissue is a made of a mass of new capillaries and fibrous tissue in a healing wound.
A granuloma is a histological (pathological) term refering to chronic inflammation in which there are several types of inflammatory cells including giant cells. Granulomas form in response to foreign bodies, certain infections (tuberculosis, leprosy) and inflammatory skin diseases (granuloma annulare [illustrated], granuloma faciale, sarcoidosis).
Ground substance is the gel component of the dermis. It contains hyaluronic acid, dermatan sulphate, & chondroitin-6-sulphate (these are anionic polysaccharides or glycosaminoglycans).
A rash that appears to be whirling in a circle.
A specialised epidermal product of the pilosebaceous structure. Terminal hair is found on the scalp and vellus hair on body surface (short, thin, light coloured).
The hair cycle has a growth phase (anagen) when the hair has a pointed tip, which lasts several years; a short involutional phase (catagen); and a resting phase with clubbed or bulbous tip (telogen), which lasts for several months.
Hemidesmosomes are the structures that stick basal keratinocytes tightly to the dermis via the basement membrane.
A herpetiform eruption means it looks like a herpes infection, with grouped umbilicated vesicles.
The horny layer of the epidermis (stratum corneum) consists of stacks of dead cells without nuclei make up the dry or keratinised stratum corneum. The top layer of cells loosens and falls off.
Hyperkeratosis or scaling is an increase in the dead cells on the surface of the skin (stratum corneum).
Hyperpigmentation may be due to hypermelanosis or haemosiderin deposits that result in skin colour that is darker than normal.
Hyperplasia is the enlargement of a tissue by an increase in cell numbers.
Some component of the skin such as a scar is enlarged or has grown excessively.
Hypopigmentation refers to skin colour that is paler than normal.
Iatrogenic illness is caused by a doctor's actions, for example a rash due to prescription of a medicine.
Immune cells found in the skin include Langerhans cells in the epidermis. Dermal immune cells are composed of lymphocytes, neutrophils, monocytes (histiocytes & activated macrophages) and mast cells. They are most often found around blood vessels. Immune cells are recruited in great numbers to heal wounds and fight infection. Many skin diseases are characterised by specific patterns of these cells.
Induration is skin that feels hard and thickened.
Infarcts are due to interrupted blood supply and result in black areas of necrotic (dead) tissue or dry gangrene.
The isomorphic or Koebner phenomenon refers to the tendency of several skin conditions to affect areas subjected to injury.
The protein produced by keratinocytes, forming the bulk of epidermis, hair and nails.
Keratinocytes are the cells that make up the ‘brick wall’ of the epidermis. They produce a protein called keratin.
The Koebner or isomorphic phenomenon refers to the tendency of several skin conditions to affect areas subjected to injury. Koebnerised lesions are often linear in shape. The illustration is of koebnerised psoriasis.
Langerhans cells are dendritic cells that present antigens to the immune system. They are found in the prickle cell layer of the epidermis.
A lesion is any single area of altered skin. It may be solitary or multiple.
Leukoderma means white skin. Also known as achromia.
Lichenification is caused by chronic rubbing, which results in palpably thickened skin with increased skin markings and lichenoid scale. It occurs in chronic atopic eczema and lichen simplex.
A lichenoid skin eruption is one that resembles lichen planus. It usually has a tight adherent scale. This term also refers to a particular pattern of inflammation seen on histology (pathological examination).
A linear shape to a lesion often occurs for some external reason such as scratching. Also striate.
Lipocytes or adipose cells are groups of fat cells forming yellow lobules in subcutaneous tissue.
Maceration describes moist peeling skin.
A macule is a small area of colour change, often defined as less than 1.5 cm diameter. The surface is smooth.
Melanin is the brown coloured protein made by melanocytes.
Pigment cells normally found in the basal layer of the epidermis. They produce a protein called melanin that protects the skin from damage due to ultraviolet radiation. Benign melanocytic tumours are often called moles. Cancerous melanocytic tumours are called malignant melanoma.
Merkel cells are sensory cells found in the epidermis. Their exact function is uncertain. The Merkel cell carcinoma is a rare form of skin cancer.
Metaplasia is a condition where one type of cell transforms into another type of cell, because of a changed environment.
Morphology is the form or structure of an individual skin lesion
The mucosa or mucous membrane is a moist lining of internal areas that opens onto the skin surface, e.g. mouth, nose, eyes, genital tissues.
The nail plate is composed of horny cells containing keratin and is produced by nail matrix. Fingernails grow 0.1mm per day; toenails 0.03mm per day.
Nikolsky sign is positive when slight rubbing of the skin results in exfoliation of the skin's outermost layer.
A nodule is an enlargement of a papule in three dimensions (height, width, length). It is a solid lesion more than 1 cm in diameter.
Round (coin-shaped) lesions. Also known as discoid.
Oedema refers to tissue swelling (American spelling ‘edema’)
The papillary dermis is the upper portion of the dermis just beneath the epidermis. It is characterised by thin haphazardly arranged collagen fibres, thin elastic fibres and ground substance.
Papules are small palpable lesions. The usual definition is that they are less than 1 cm diameter. They are raised above the skin surface, and may besolitary or multiple.
A patch refers to a large area of colour change, with smooth surface.
The isomorphic phenomenon resulting in ulceration i.e. ulcers appearing at the sites of minor trauma such as venepuncture (blood test).
Pedunculated means a lesion has a peduncle or is on a stalk.
Perioral distribution means the dermatosis is around the mouth. Also ‘periocular’, ‘perianal’ and so forth.
Petechiae are small red, purple or brown spots - a form of purpura.
The pilosebaceous structures contain hair and sebaceous glands (oil glands).
Pityriasis refers to a skin condition with a bran-like powdery scale.
A plaque is a palpable flat lesion usually greater than 1 cm diameter. Most plaques are elevated, but a plaque can also be a thickened area without being visibly raised above the skin surface. They may have well-defined or ill-defined borders. The name 'plaque' is derived from the French word for plate.http://grovemark.com/index.php/admin/cms_page/edit/page_id/15/key/96127555fb41c7c862e9d93aa413343d/
Poikiloderma is skin with a variegated appearance, usually mixed pallor, telangiectasia & pigmentation.
A polygonal skin lesion means it has a non-geometric shape.
A polymorphic eruption means the lesions may have varied shapes.
The prickle cell layer of the epidermis (stratum spinosum or spinous cell layer) is so-called because prominent adherence plates (desmosomes) look spiny. The keratinocytes become increasingly flat as they mature and move upwards towards the skin surface.
Purpura is bleeding into the skin. This may be as petechiae or ecchymoses. Purpura does not blanch with pressure (diascopy).
A pustule is a collection of pus. It is filled with neutrophils, and may be white, or yellow. Not all pustules are infected.
A rash is a widespread eruption of lesions.
The reticular dermis is the lower portion of the dermis. It is composed of coarse elastic fibres and thick collagen bundles parallel to the skin surface.
Scaling or hyperkeratosis is an increase in the dead cells on the surface of the skin (stratum corneum). Scale can be described as furfuraceous or pityriasiform (bran-like), psoriasiform (psoriasis-like), hyperkeratotic (thick), adherent or minimal.
Hardened scar-like or indurated tissue as in localised scleroderma.
Sebaceous glands produce an oily substance known as sebum. They are most concentrated on scalp & face where circulating androgens induce increased secretion at puberty. They mostly open into the outer portion of hair follicle and directly onto skin surface on breast and genitals.
A serpignous lesion is in the shape of a snake or serpent.
Sessile skin lesions appear to be stuck directly onto the skin surface without a stalk.
Squamous cells are flat epithelial cells found on the skin surface. The structure of skin is described as a stratified squamous epithelium, referring to the way the cells are built up in layers.
The horny layer consisting of stacks of dead cells without nuclei make up the dry or keratinised stratum corneum. The top layer of cells loosens and falls off.
This is the granular layer of the epidermis is characterised by flattened cells filled with dark granules containing keratohyaline protein.
This is the prickle cell layer of the epidermis, which contains increasingly flat keratinocytes that arise as the epidermal cells mature and move upwards towards the skin surface. They are also called spinous cells.
Subcutaneous tissue or subcutis is the bottom layer of he skin and is composed of fat cells (adipose cells or lipocytes), connective tissue, blood vessels and nerves.
Concentric rings like a dartboard. Also known as iris lesion.
Telangiectasia is the name given to prominent cutaneous blood vessels. They are red or purple in colour.
Telogen is the resting phase of the hair cycle. Telogen hairs have a clubbed or bulbous tip and last for several months before falling out (shedding).
An ulcer is full thickness loss of epidermis or epithelium and dermis and may involve subcutaneous tissue. An ulcer heals with a scar. It may be covered with an eschar.
Umbilicated papules or vesicles have a central dell, such as is seen with molluscum contagiosum or herpes simplex infections.
Venulectasia is the name given to prominent venules, blue in colour and often on the lower legs.
Verrucous means wart-like, ie. thickened and scaly.
Vesicles are small fluid-filled blisters less than 1cm in diameter. They may be single or multiple. The fluid may be clear or blood-stained.
A weal, also spelled ‘wheal’ is an oedematous papule or plaque caused by swelling in the dermis. Wealing indicates urticaria or an urticaria-like condition.
Wood lamp emits long wavelength UVA used to examine the skin pigmentary changes and fluorescent infections such as cat ringworm.