There are many causes of children’s rashes (Tables 27.1 and 27.2). The papular rash scabies is described in Chapter 21. The scaly rashes atopic eczema and psoriasis (Figures 27.1 and 27.2) are described in Chapters 12 and 13. Urticaria is described in Chapter 32. For the blistering rashes, bullous impetigo see Chapter 18 and epidermolysis bullosa see Chapter 46.

Warning

A febrile child with a non-blanching petechial and/or purpuric rash should be treated promptly with systemic antibiotics for presumed meningococcal septicaemia.

Macular (± Papular) Rash

Measles presents as an erythematous maculopapular rash starting on the face, spreads to the trunk and fades over a few days. Koplik’s spots (transient clusters of white papules with red halo) on the buccal mucosa, fever, cough and lymphadenopathy occur. Incidence of measles in the UK has risen because of some children missing their measles, mumps and rubella (MMR) vaccination. Treatment is symptomatic with monitoring for complications (e.g. pneumonia). Diagnosis is clinical but viral DNA may be identified on blood culture.

Papular Rash

Molluscum contagiosum (Figure 27.3) is a common poxvirus infection. Skin-coloured papules with central umbilication develop on the trunk, face or limbs. Lesions are self-limiting but treatments include cryotherapy, curettage or topical 5% imiquimod cream.

Papular–Vesicular Rash

Chickenpox is a highly contagious airborne disease caused by varicella zoster virus. Patients present with general malaise, fever and an itchy papular–vesicular rash on the head and trunk; lesions heal over a week with or without scarring. Diagnosis is usually clinical. Treatment is symptomatic with monitoring for complications (e.g. pneumonia); antiviral treatment (e.g. aciclovir) started within 48 hours of the rash onset may decrease the disease severity. Reactivation of the varicella zoster virus causes shingles (herpes zoster).