How are skin rashes described?

Skin rashes can be described in the following way:

• Redness of the skin (called eritema).

• Flat abnormally coloured areas of skin (called macules). Macules are often either red, dark red or purple, brown or white.

• Solid raised areas which are up to half a centimetre across (called papules).

• Solid raised areas which are more than half a centimetre across (called nodules).

• Areas of red raised skin (called plaques) e scales, which have a flaky silvery-white appearance.

• Reddish-purple lesions which do not fade with pressure (called purpura):
  

  • If less than one centimetre across then these are called petechiae.

  • If more than one centimetre across then they are called ecchymoses.

• Blisters: these are swellings of the skin containing fluid:

  • If a blister is less than half a centimetre across then it is called a vesicle. If filled with yellow fluid (pus) then it is called a pustule.

  • If a blister is larger than half a centimetre across it is called a bulla (plural is bullae).

Skin disorders that can cause itching include (please click the links to separate leaflets which provide further information):

• Pele seca.

• Eczema.

• Dermatite de contato.

• Urticaria.

• Líquen plano.

• Psoríase.

• Foliculite.

• Prickly heat/heat rash.

Please click the links to separate leaflets which provide further information:

Red (erythema) but not scaly skin rash

• A skin infection called celulite.

• An allergic reaction called urticária.

• Reaction to a medicine you are taking.

• Queimaduras.

• Erupções virais - eg, sarampo ou rubéola (sarampo alemão).

• Vasculitis. This is a condition involving inflammation of blood vessels, which may occur with various illnesses, including artrite reumatoide.

• Eritema nodoso. This is a condition which causes red rounded lumps (nodules), most commonly on the shins.

• Redness on the palms of your hands may be caused by liver disease, pregnancy or an glândula tireoide hiperativa (hipertireoidismo).

• A red rash may occasionally be due to an inflammatory condition called lúpus eritematoso sistêmico, especially if it is on the cheeks.

Red (erythema) and scaly skin rash

• Psoríase. This is a condition where there is inflammation of the skin.

• Eczema. This is sometimes called dermatitis and also involves inflammation of the skin. It may be caused by an allergy and is then called atopic dermatitis/eczema. This may happen in response to some plants - eg, poison oak or ivy.

• Dermatite seborreica (in adults). This is a type of skin rash sometimes called seborrhoeic eczema. In babies it is known as cradle cap.

• Fungal (or 'yeast') skin infection, such as pé de atleta, groin infection (tinea cruris), ringworm, scalp ringworm or infection with candida.

• Pitiríase rósea. This condition is described as 'self-limiting' and the rash will clear itself naturally.

• Pitiríase versicolor. This is a rash which is caused by a yeast-like germ.

• Lúpus eritematoso.

• Líquen plano. This condition mainly affects the skin and causes an itchy rash.

Macules

• Red macules may be due to a reaction to a medicine or a viral rash - such as sarampo ou rubéola - as well as other causes.

• A brown macule may be a mole but check with your doctor if a mole changes or you are concerned it might be a melanoma.

• A white macule may be due to a condition which causes pale patches of skin (called vitiligo) or a skin complaint with flaky discoloured areas (called pitiríase versicolor).

• If a macule is dark red or purple and does not fade when you put pressure on it then it is a purpura (see below) and you need to see a doctor urgently. This is because it could be a sign of meningite or blood infection (septicemia).

Papules

• Common causes of papules include cicatrizes de acne, viral wart, seborrhoeic wart, molusco contagioso, sarna, picadas de insetos and skin tags.

• Other causes include psoríase.

Purpura and petechiae

• These are dark red or purple and don't fade when you press them. You need to see a doctor urgently because there may be a serious cause that needs urgent treatment, such as infecção meningocócica.

• However, common causes include injury to the skin or repeated coughing. More serious common causes include liver disease such as cirrose.

• Less common causes include vasculitis (eg, Púrpura de Henoch-Schönlein) or a low level of platelets in your blood (eg, púrpura trombocitopênica trombótica).

Vasculite

© James Heilman, MD, CC BY-SA 3.0, via Wikimedia Commons

Nodules

• Common causes of a nodule include a sebaceous cyst, lipoma, câncer de pele, or a wart.

• Other causes include rheumatoid nodules (associated with artrite reumatoide) and Heberden's nodes (associated with osteoartrite).

Blisters

• Skin inflammation, including reactions to medicines, dermatite de contato, eczema. Eczema on your legs may be caused by varicose veins (eczema varicoso).

• Diseases of your immune system - eg, pemphigoide bolhosa.

• Viral infections - eg, catapora, doença mão-pé-boca.

• Skin infection: a germ (bacterial) infection with impetigo or viral infection with herpes simplex (herpes labial ou herpes genital) or with herpes zoster (shingles).

• Rarer causes include pênfigo e pemphigoid.

Pustules

• Skin infection by a virus (eg, herpes labial due to herpes simplex virus) or bacterial germs (impetigo).

• Inflammation - eg psoríase.

• Pustular skin reaction to medicine you are taking.

• Pustules on your face may be acne or rosacea.

Úlceras

Ulcers may be due to venous leg ulcers, úlceras de pressão, diabetes skin ulcers ou cancerous (malignant) skin ulcers.

This leaflet is a guide but if you have any concerns, you must telephone or see your GP, especially if:

• The rash doesn't quickly disappear.

• Você se sente mal.

• The rash does not fade with pressure (the best way to test this is to press a glass gently against the rash to see if it fades).

• You are not sure what has caused the rash or have any other concerns.