Red blanching (erythematous) rashes
Causes vary with age. Viral causes commonest in younger children. In older children, eczema, psoriasis, and drug reactions (e.g. reaction to am-picillin in glandular fever) predominate.
See b Plate 7. Culprits include:
• enteroviruses (coxsackie or echovirus);
• human herpes virus 6 (roseola infantum);
• parvovirus b19 (erythema infectiosum);
Usually associated with fever and widespread non-specific macular or mac-ular–papular erythematous rash. If child is significantly unwell, lethargic, or peripheral perfusion is reduced, admit and investigate (may be bacterial sepsis). Otherwise, simply reassure and advise symptomatic treatment.
Erythematous macular–papular rash commonest (e.g. to penicillins, cepha-losporins, anticonvulsants). Drugs may also cause:
• Urticaria (e.g. opiates, NSAIDs, penicillins, cephalosporins).
• Exfoliative dermatitis (e.g. sulphonamides, allopurinol, carbamazepine).
• Erythema multiforme or Stevens–Johnson syndrome/toxic epidermal necrolysis (e.g. anticonvulsants, antibiotics and allopurinol).
• Discontinue offending drug, may need prick or patch testing to identify.
• Symptomatic treatment (e.g. antihistamines or emollients for pruritus).
Conditions overlap. Erysipelas is superficial skin infection whereas cellulitis involves deeper subcutaneous tissues. Usually due to Strep. pyogenes or Staph. aureus; occasionally Haemophilus influenzae.
• Tender, warm, spreading, sharply marginated erythema +/– oedema.
• May also have ascending red streaks of lymphangitis.
• Regional lymphadenopathy, fever, malaise.
• Deeper infection may co-exist, e.g. osteomyelitis.
• Swab skin and blood culture.
• If erysipelas alone, IV penicillin (erythromycin if penicillin-allergic).
Cellulitis: raise affected part (e.g. limb); combination of IV penicillin and flucloxacillin. Consider cefotaxime instead of penicillin if child aged <5yrs and not immunized against Haemophilus.
Crops of pink truncal rings (lesions fade rap-idly, only to recur) caused by rheumatic fever. No treatment required.
Typically affects older children. Caused by immunological reaction to:
• Streptococcal infection.
• Mycoplasma infection.
• Idiopathic (30%).
Multiple discrete, large, red, hot, tender nodules on shins (occasionally thigh and forearms) appear over 10 days. Nodules resolve over 3–6wks, with colour changes similar to fading bruises. Fever, malaise, arthralgia, particularly of knees, may also occur.
Investigate for infection. Treat underlying disease; give analgesics.
Caused by excessive UV light exposure. Sun avoid-ance, skin covering, hats, and water-resistant high-factor sunscreens are preventative! Fair-skinned individuals, infants, and those with pre-existing hypopigmented disorders are at particular risk.
• Presentation: painful, tender erythema +/– blistering over exposed area. Resolves with skin peeling.
• topical calamine lotion;
• topical corticosteroids if severe.
• excessive friction between skin surfaces;
• obesity is a predisposing factor.
• moist, erythematous eruption typically affecting the groin, axillae, neck, submammary areas;
• s Candida infection common.
o treat inflammation and infection, e.g. topical antibiotic, topical antifungal and low potency topical steroid;
o improve general hygiene;
• expose to air.
Meningococcal disease, as well as other bacterial patho-gens, can present with an erythematous rash.