The skin is often referred to as the largest body organ and serves as the main protective barrier against damage to internal tissues from trauma, ultraviolet light, temperature, toxins and bacteria. The skin is also responsible for sensory perception, temperature regulation, production of vitamin D and excretion of waste products. In addition to preventing harmful substances from entering the body, it also controls the loss of vital substances from the body. It is therefore important that the skin remains intact to allow the body to perform these essential functions.
The skin contains a number of accessory organs which assist in its protective role. It consists of two main layers: the epidermis, or outer layer, and the dermis, which lies beneath the epidermis.The thickness of the skin varies depending on the site, with thicker skin being present on areas of the body that experience friction or wear and tear, such as the soles of the feet and palms of the hand. The skin is supported by a layer of fatty tissue, sometimes known as the hypodermis. This fatty area helps to act as a cushion to protect the body and is also important for insulation.
Common skin conditions in children
Varicella zoster virus causes chickenpox and shingles. Chickenpox commonly occurs in childhood. By the age of 10 years most children, particularly in urban communities, will have been infected. Primary infection confers long-term immunity but the virus remains dormant in the dorsal root ganglion to be reactivated as shingles.
The incubation period is 13−17 days. The patient may be feverish before developing a rash which will start with pink macules. These quickly develop into papules, tense vesicles, pustules then crusts. The condition is communicable from five days before the rash develops until around six days after. The spots can be very itchy and secondary infection may lead to pock-like scarring
Atopy means an inherited predisposition to eczema, asthma or hay fever and atopic individuals may have one or all of these conditions. Eczema usually begins between 3 and 12 months. The condition tends to be long term, but it will clear by puberty in 90% of individuals.
In an acute reaction, the skin displays the signs of inflammation: heat, erythema and swelling. Pain is not usually present but itching is severe. The skin lesions are not sharply demarcated but merge with the surrounding skin. There may be vesicles or bullae which rupture with oozing of clear fluid. The lesions may be localised, particularly to the flexures, or widespread. In Asian or Afro-Caribbean skin, lesions are more commonly seen on the extensor surfaces.
This is a form of vasculitis (inflammation of the small blood vessels) in the skin and various other tissues in the body. It may also be referred to as anaphylactoid purpura. The precise cause is unknown. Three-quarters of cases are preceded by an upper respiratory tract infection, mostly caused by ß haemolytic streptococci. Several other associations have been reported including drugs, food and various infections.
The rash consists of erythematous and purpuric macules and papules together with vesicles and pustules. It should be considered in any child with purpura and a normal platelet count. It may follow a streptococcal throat infection. There may be associated arthralgia and abdominal pain. There may also be renal involvement
A superficial infection of the epidermis caused by Staphlococcus aureus, a group A beta-haemolitic streptococcus or a mixture of both. Entrance is gained through broken skin such as cuts and grazes. The condition is highly contagious.
Typically starts as vesicles which rapidly break down to form honeycoloured crusts; less commonly, there may be just a glazed erythema. Sites usually involved are the face and neck but it can spread extensively over the body.
Secondary infection, most commonly with Staphlococcus aureus or streptococcal isolates, can occur in the broken skin caused by scratching in atopic eczema.
It is important to establish if the patient has a history of atopic eczema. The diagnosis is made by the history of the preceding erythema and rash. The skin may be weeping with papules and crusts and be rapidly worsening despite using standard treatment for eczema.
Miliaria (sweat rash) arises from obstruction of the sweat glands. It is most commonly found in hot, humid conditions.
Typically, folliculitis develops in the skin folds and on the body, especially in areas of friction from clothing. In infants, lesions commonly appear on the neck, groins and axillae but can also appear on the face and elsewhere. In contrast to acne and other forms of folliculitis, miliaria spots do not arise around hair follicles.
- Miliaria crystalline is caused by obstruction of the sweat ducts and appears as tiny superficial clear blisters.
- Miliaria rubra (prickly heat) occurs deeper in the epidermis and results in itchy red plaques. Miliaria profunda results from sweat leaking into the dermis causing deep, intense, uncomfortable, prickling red lumps.
- Miliaria pustulosa describes pustules due to inflammation and bacterial infection
Measles is a highly contagious disease caused by the RNA morbillivirus. Immunisation can prevent measles but the disease is becoming more common with reduced uptake of vaccination.
After an incubation period of around 10 days, the child becomes miserable with symptoms similar to a common cold, including: a high fever; runny nose; conjunctivitis; photophobia; brassy cough; and inflamed tonsils. Koplik spots on the buccal mucosa are diagnostic at this stage (these look like grains of salt on a red base). Around day 4, a red macular rash will appear behind the ears and spread to the face, trunk and limbs. The macules may become papules which join together and become confluent. It lasts up to 10 days and leaves brown staining and some scaling.
The common type of nappy rash is an irritant contact dermatitis, caused by urine and faeces being held next to the skin under occlusion. Bacteria in the faeces break down the urea in the urine into ammonia which irritates the skin.
The rash will be patchy and tends to involve the skin in contact with the nappy (buttocks, genitalia, thighs); the skin folds may be spared. Only erythema is present in mild cases, but erosion or even ulceration can occur in severe cases. The affected area is sore and cleaning or bathing causes much discomfort.
Rubella (German measles)
Rubella, caused by a rubivirus, is a common viral illness in children. It is spread by inhalation of infected droplets.
After an incubation period of 14−21 days, a macular rash begins on the face and neck. It spreads down the body in 24−48 hours then clears from the face downwards in 2−3 days. It is associated with enlarged occipital and posterior cervical lymph nodes and, occasionally, an arthritis. The child is infectious from 3−5 days after the rash appears.