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, sex, 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. However, 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., roseola) to life-threatening illnesses such as meningococcal disease.
Several systemic conditions with a serious clinical course may have a rash as a component and should be assessed urgently if suspected (see Urgent considerations).
Macule: a flat area of colour change <1 cm in size (e.g., viral exanthem [such as measles and rubella], morbilliform drug eruption).
Patch: a large macule >1 cm in size (e.g., viral exanthem [such as measles and rubella], morbilliform drug eruption).
Papule: a raised area <1 cm in size (e.g., wart).
Nodule: a larger papule, >1 cm in size (e.g., nodular prurigo).
Plaque: a flat-topped raised area (a cross between a nodule and a patch; e.g., psoriasis).
Vesicle: a small fluid-filled lesion (blister) <0.5 cm in size (e.g., varicella, eczema herpeticum).
Bulla: a larger vesicle >0.5 cm (e.g., bullous impetigo).
Pustule: a pus-filled lesion (e.g., folliculitis).
Wheal: a transient raised papule or plaque caused by dermal oedema (e.g., urticaria).
Scale: flakes of stratum corneum (e.g., eczema, psoriasis).
Crust: dried serum, blood, or purulent exudate on the skin surface (e.g., impetigo).
Erosion: loss of epidermis, heals without scarring (e.g., Stevens-Johnson syndrome, toxic epidermal necrolysis).
Ulcer: loss of epidermis and dermis, heals with scarring (e.g., venous ulcer, pyoderma gangrenosum).
Excoriation: loss of epidermis following trauma such as scratching (e.g., pruritus).
Fissure: a split in the skin (e.g., angular cheilitis, palmoplantar keratoderma).
Lichenification: thickening of the skin with accentuation of skin markings (e.g., chronic eczema, lichen simplex chronicus).
Purpura: an area of colour change (red or purple) due to bleeding into the skin; does not blanch on pressure (e.g., vasculitis, disseminated intravascular coagulation).
Petechia: a pin-point purpuric lesion (e.g., vasculitis, disseminated intravascular coagulation).
Ecchymosis: a larger area of purpura (e.g., vasculitis, disseminated intravascular coagulation).
- Roseola infantum (sixth disease)
- Erythema infectiosum (fifth disease)
- Epstein-Barr virus (EBV) infection
- Atopic dermatitis
- Seborrhoeic dermatitis
- Irritant contact dermatitis
- Pityriasis rosea
- Tinea corporis
- Insect bites or stings
- Erythema toxicum neonatorum
- Child abuse
- Cutaneous candidiasis
- Cutaneous herpes simplex
- Molluscum contagiosum
- Measles (rubeola)
- Cytomegalovirus (CMV) infection
- Dengue fever
- 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
- Meningococcal disease
- Scarlet fever
- Staphylococcal scalded skin syndrome
- Toxic shock syndrome
- Bacterial endocarditis
- Food allergy
- Immune thrombocytopenia
- Kawasaki disease
- Juvenile arthritis
- Henoch-Schonlein purpura
- Systemic lupus erythematosus
- Rheumatic fever
- Miliaria crystallina
- Transient neonatal pustular melanosis
Professor Emeritus of Pediatrics and Dermatology
Indiana University School of Medicine
Riley Hospital for Children
PT declares that her spouse owns stocks in Eli Lilly and Company.
Clinical Professor of Dermatology
Columbia University College of Physicians and Surgeons
New York City
NS declares that she has no competing interests.
Professor in Pediatrics
Department of Pediatrics
National University Hospital
HVB declares that he has no competing interests.
Associate Professor of Pediatrics
West Virginia University School of Medicine
LN is an author of a reference cited in this topic.
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