Childhood rashes are cutaneous eruptions of acute onset. Clinically, they may be categorised as maculopapular, pustular, vesiculobullous, diffuse/erythematous, or petechial/purpuric in nature. However, in many aetiologies these forms may co-exist or evolve from one form to another.
Initial considerations in evaluating a rash in children include its morphology, duration, and distribution. Age, gender, family history, medications, known allergies, and exposures are also of primary importance.
Generally, rash in the absence of fever or systemic symptoms is not urgent. When fever or signs of illness are present, urgent evaluation and treatment must be considered. The differential diagnosis is extensive, ranging from self-limiting conditions (e.g., scabies) to life-threatening illnesses such as meningococcal septicaemia.
Several systemic conditions with a serious clinical course may have a rash as a component and should be assessed urgently if suspected.
Macule: a flat skin lesion <1 cm in greatest diameter. When a macular lesion extends beyond 1 cm, the appropriate term is a patch.
Papule: a raised bump <1 cm in diameter. When papular lesions are >1 cm in size, the appropriate term is a plaque (palpable lesions elevated above the skin surface) or a nodule (a larger, firm papule with a significant vertical dimension).
Pustule: a raised blister containing purulent fluid.
Vesicle: a papule containing clear, serous fluid.
Bulla: a larger vesicle >1 cm.
Urticaria: a wheal or hive.
Morbilliform eruption: rash that resembles that of measles.
Petechiae: small haemorrhages of skin capillaries.
Purpura: larger areas of bleeding into the skin.
Erythema marginatum: a fleeting pink rash typically involving the trunk and proximal extremities.
Erythema nodosum: a hypersensitivity reaction involving the subcutaneous fat, presenting as red, tender nodules most commonly over shins, calves, and buttocks.
Target lesions: annular erythematous rings with an outer erythematous zone and central blistering sandwiching a zone of normal skin tone.
Targetoid lesions: similar to target lesions but without central blistering.
- Roseola infantum (sixth disease)
- Erythema infectiosum (fifth disease)
- Epstein-Barr virus infection
- Atopic dermatitis
- Seborrhoeic dermatitis
- Irritant contact dermatitis
- Pityriasis rosea
- Tinea corporis
- Insect bites or stings
- Child abuse
- Cutaneous candidiasis
- Cutaneous herpes simplex
- Molluscum contagiosum
- Rubeola (measles)
- Cytomegalovirus infection
- Hepatitis B
- Hepatitis C
- HIV seroconversion
- Rubella (German measles)
- Hand-foot-and-mouth disease
- Allergic contact dermatitis
- Rocky Mountain spotted fever
- Lyme disease
- Simple drug eruption
- Stevens-Johnson syndrome/toxic epidermal necrolysis
- Drug reaction with eosinophilia and systemic symptoms (DRESS)
- Erythema multiforme
- Systemic hypersensitivity syndrome
- Scarlet fever
- Staphylococcal scalded skin syndrome
- Toxic shock syndrome
- Bacterial endocarditis
- Food allergy
- Idiopathic thrombocytopenic purpura
- Kawasaki disease
- Juvenile arthritis
- Henoch-Schonlein purpura
- Systemic lupus erythematosus
- Rheumatic fever