A to Z of skin diseases

ACNE Acne is a very common skin condition characterised by comedones (blackheads and whiteheads) and pus-filled spots (pustules). It usually starts at puberty and varies in severity from a few spots on the face, back and chest, which most adolescents will have at some time, to a more serious problem that may be embarrassing, sap self-confidence and cause scarring. For the majority it tends to resolve by the late teens or early twenties but can persist for longer in some people. Acne can develop for the first time in people in their late twenties or even the thirties. It occasionally occurs in young children.

ALOPECIA AREATA Alopecia is a general term for hair loss. Alopecia areata is a specific, common cause of hair loss that can occur at any age. It usually causes small, coin-sized, round patches of baldness on the scalp, although hair elsewhere such as the beard, eyebrows, eyelashes, body and limbs can be affected. Occasionally it can involve the whole scalp (alopecia totalis) or even the entire body and scalp (alopecia universalis). It is not possible to predict how much hair will be lost. Regrowth of hair in typical alopecia areata is usual over a period of months or sometimes years, but cannot be guaranteed. The hair sometimes regrows white, at least in the first instance. Further hair loss is not uncommon. In alopecia totalis and alopecia universalis, the likelihood of total regrowth is less.

BASAL CELL CARCINOMA A basal cell carcinoma (BCC) is a type of skin cancer. There are two main types of skin cancer: melanoma and non-melanoma skin cancer. BBC is a non-melanoma skin cancer, and is the most common type (> 80%) of all skin cancer (skin cancer incidence is < 1%) in the UK. BCC are sometimes referred to as ‘rodent ulcers’.

BOWEN'S DISEASE Bowen’s disease is also known as intraepidermal squamous cell carcinoma, and is a growth of cancerous cells that is confined to the outer layer of the skin. It is not a serious condition, and its importance rests on the fact that, occasionally, it can progress into an invasive skin cancer (squamous cell carcinoma). For this reason, dermatologists usually treat, or at least keep an eye on, Bowen's disease.

CONGENITAL ERYTHROPOIETIC PORPHYRIA The porphyrias are a group of diseases caused by abnormalities in the production by the body of chemicals called porphyrins. Porphyrins are very important as they form haemoglobin that carries oxygen around the body in the red blood cells. The production of haemoglobin involves a chain of reactions in which one porphyrin is converted to another, and the porphyrias are diseases that result from genetic abnormalities in this process. If there is a block in the chain of reactions, there will be a build-up in the body of a particular porphyrin (which depends on where the block occurs), and porphyrins in high concentration are damaging to tissues. The problems caused by the different porphyrias relate to the particular porphyrin that accumulates.

Contact Dermatitis The words ‘dermatitis’ and ‘eczema’ are interchangeable and mean the same thing. Contact dermatitis, therefore, is the same thing as contact eczema. For simplicity we will stick to the word ‘dermatitis’ in this leaflet.

Darier's Disease It is a rare inherited skin condition, in which the skin in certain areas develops large numbers of small brownish warty bumps.

Eczema (Atopic Eczema) It is a rare inherited skin condition, in which the skin in certain areas develops large numbers of small brownish warty bumps.

Epidermolysis Bullosa Simplex Epidermolysis bullosa (EB) simplex is a rare inherited skin disorder which causes blistering. In the most common form, blisters tend to be confined to the palms and soles, although occasionally they arise in the mouth, and are most troublesome during warm weather. The more severe form is called EB simplex Dowling-Meara and those affected have more widespread blistering which does not vary according to the time of year. EB simplex is different from the junctional and dystrophic forms of EB, and if you have EB simplex you will not go on to develop these other types of EB.

Fungal infection of the nails Fungal infections of the nails are also known as onychomycosis, as tinea unguium, and as ringworm of the nails. The fungi in question are usually those that cause athlete’s foot – a common infection of the skin of the feet. In athlete’s foot the fungi live in the keratin that makes up the outer layer of the skin, but they can also invade the hard keratin of which nails are made. When this happens, the result is a fungal infection of a nail.

Hailey-Hailey disease Hailey-Hailey disease is also known as familial benign chronic pemphigus. It is a rare inherited skin condition, in which red scaly areas or small blisters appear at sites of friction.

Herpes Simplex Herpes simplex is an infection of the skin with the herpes simplex virus. This can be caught from another person after direct skin-to-skin contact, mouth contact, or sexual contact. The first time the virus is caught, it does not always show up on the skin, but can lie dormant within special parts of the sensory nerves (the sensory nerve ganglia). Later in life, the virus can become active again and appear as herpes simplex on the skin. The commonest areas to be affected by herpes simplex are the lips (as cold sores) and the genital area (as genital herpes).

Hidradenitis Suppurativa Hidradenitis suppurativa is a chronic and stubborn disease centred on inflammation of the large specialised sweat glands (apocrine glands) that are found mainly in the armpits and groins. These areas show a distinctive mixture of boil-like lumps, areas leaking pus, and scarring.

Hirsutism Hirsutism is the term used when a woman grows too much body or facial hair in a pattern seen normally occurring only in men.

Ichthyosis Ichthyosis is the term used to describe continual and widespread scaling of the skin. It may be inherited (genetic) or acquired during life. The inherited forms are rare, generally present from infancy, and are usually lifelong conditions. Acquired ichthyosis can develop at any age due to a number of medical problems, such as kidney disease.

Impetigo Impetigo is a bacterial infection of the surface of the skin. In the it is the most common skin infection seen in young children.

Keloids When a wound heals, it leaves a scar. A keloid is a special type of scar: one that grows too much and can even become larger than the original wound. It is not uncommon for surgical or injury scars to become a little lumpy (hypertrophic). A keloid differs from these in several ways: A keloid can come up after very minor skin damage, such as an acne spot, or even if there has been no obvious damage to the skin at all. It can spread outside the original area of skin damage. It may last for many years.

Keratosis pilaris Keratosis pilaris is a very common and completely harmless skin condition. In the population as a whole, keratosis pilaris may affect as many as one person in three. Its name gives some idea of what it is; ‘keratosis’ means that there is too much keratin, which makes up the tough horny outer layer of the skin, while ‘pilaris’ comes from the Latin for hair (pilus). In keratosis pilaris, many small (1 to 2 mm across) horny plugs can be seen blocking the hair follicles on the upper and outer parts of the arms and thighs. This can look like goose bumps, but feels slightly rough.

Lichen Planus Lichen planus is a fairly common, itchy, non-infectious type of rash that usually occurs in adults. Doctors use the word ‘lichen’ to mean small bumps on the skin. ‘Planus’ means ‘flat’, and tells us that the small itchy bumps that make up the rash of lichen planus have shiny flat tops.

Melasma Melasma, also called ‘chloasma’, is a common skin condition of adults in which light to dark brown or greyish pigmentation develops, mainly on the face. The name comes from melas, the Greek word for black. Although it can affect both genders and any race, it is more common in women and people with darker skin-types who live in sunny climates. Melasma usually becomes more noticeable in the summer and improves during the winter months. It is not an infection, it is not contagious and it is not due to an allergy. Also, it is not cancerous and will not change into skin cancer.

Pemphigus vulgaris Pemphigus vulgaris is a rare autoimmune disease that causes severe blistering of the skin and of the mucous membranes lining the mouth, nose, throat and genitals. The blisters have thin roofs and break easily to leave raw areas (erosions) that can be extensive and painful. Pemphigus does not go away by itself, and always needs treatment by a specialist.

Plantar Warts (Verrucas) Warts are localised thickenings of the skin, and the term ‘plantar warts’ is used for those that occur on the soles of the feet (the ‘plantar’ surface). They are also known as verrucas.

Psoriasis Psoriasis is a common skin problem affecting about 2% of the population. It occurs equally in men and women, at any age, and tends to come and go unpredictably. It is not infectious, and does not scar the skin.

Rosacea Rosacea is a common rash, found on the central part of the face, usually of a middle-aged person. A tendency to flush easily is followed by persistent redness on the cheeks, chin, forehead and nose, and by crops of small inflamed red bumps and pus spots.

Scabies Scabies is a common and very itchy skin condition caused by human scabies mites. It can affect people of any age but is most common in the young and the elderly.

Shingles Shingles (also known as herpes zoster) is a painful blistering rash caused by the same virus that causes chickenpox (the varicella zoster virus).

Vitiligo Vitiligo is a condition in which areas of skin lose their normal pigment and so become white. It is common, and affects about 1% of the world’s population.