Rash is a common complaint, particularly during infancy. Most rashes are not serious.
Etiology of Rash in Infants and Young Children
Rashes can be caused by infection (viral, fungal, or bacterial), contact with irritants, atopy, drug hypersensitivity, other allergic reactions, inflammatory conditions, or vasculitides ( see Table: Some Causes of Rash in Infants and Children).
The photo shows lesions of molluscum contagiosum. Lesions are typically 1 to 5 mm, solitary or grouped, firm, painless papules. They are pearly to pink in color, dome shaped, and may be umbilicated.
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This photo shows very severe lesions on the face of a child with HIV infection. Giant molluscum indicates advanced immunodeficiency.
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This photo shows irritant diaper dermatitis (“W-dermatitis”).
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Image provided by Thomas Habif, MD.
This photo shows severe diaper dermatitis due to neglect.
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Erythema multiforme is characterized by target or iris lesions, which are annular lesions with a violaceous center and pink halo separated by a pale ring.
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
This photo shows small, pearl-colored cysts commonly seen on the face of neonates.
SCIENCE PHOTO LIBRARY
This photo shows fluffy white exudate on the tongue of a child with HIV infection.
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Atopic dermatitis usually develops in infancy. In the acute phase, lesions appear on the face and then spread to the neck, scalp, and extremities.
Image provided by Thomas Habif, MD.
This photo shows allergic contact dermatitis on the forearm of a child after a temporary, black "henna" tattoo was applied.
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Skin manifestations of allergic contact dermatitis range from erythema through vesiculation to edema with bullae. Changes often occur in a pattern or distribution that suggests a specific exposure. In this image, linear streaking on an extremity suggests plant contact (eg, poison ivy or poison sumac).
Image provided by Thomas Habif, MD.
Overall, the most common causes of rash in infants and young children include
Diaper rash (with or without candidal infection)
Viral exanthem
Numerous viral infections cause rash. Some (eg, chickenpox and measles, both of which are currently uncommon because of vaccination but should be considered in unvaccinated children; erythema infectiosum) have a fairly typical appearance and clinical manifestation; others are nonspecific. Cutaneous drug reactions are usually self-limited maculopapular exanthems, but sometimes more serious reactions occur.
Uncommon but serious causes of rash include
Evaluation of Rash in Infants and Young Children
History
History of present illness focuses on the time course of illness, particularly the relationship between the rash and other symptoms.
Review of systems focuses on symptoms of causative disorders, including gastrointestinal symptoms (suggesting immunoglobulin A–associated vasculitis [formerly called Henoch-Schönlein purpura] or hemolytic-uremic syndrome), joint symptoms (suggesting immunoglobulin A–associated vasculitis or Lyme disease), headache or neurologic symptoms (suggesting meningitis or Lyme disease).
Past medical history should note any drugs recently used, particularly antibiotics and anticonvulsants. Family history of atopy is noted.
Physical examination
Examination begins with a review of vital signs, particularly to check for fever. Initial observation assesses the infant or child for signs of lethargy, irritability, or distress. A full physical examination is done, with particular attention to the characteristics of the skin lesions, including the presence of blistering, vesicles, petechiae, purpura, or urticaria and mucosal involvement. Children are evaluated for meningeal signs (neck stiffness, Kernig and Brudzinski signs), although these signs are often absent in children < 2 years.
Red flags
The following findings are of particular concern:
Blistering or skin sloughing
Diarrhea and/or abdominal pain
Fever and inconsolability or extreme irritability
Mucosal inflammation
Petechiae and/or purpura
Urticaria with respiratory distress
Interpretation of findings
Well-appearing children without systemic symptoms or signs are unlikely to have a dangerous disorder. The appearance of the rash typically narrows the differential diagnosis. The associated symptoms and signs help identify patients with a serious disorder and often suggest the diagnosis ( see Table: Some Causes of Rash in Infants and Children).
Bullae and/or sloughing suggest staphylococcal scalded skin syndrome or Stevens-Johnson syndrome and are considered dermatologic emergencies. Conjunctival inflammation may occur in Kawasaki disease, measles, staphylococcal scalded skin syndrome, and Stevens-Johnson syndrome. Any child presenting with fever and petechiae or purpura must be evaluated carefully for the possibility of meningococcemia. Bloody diarrhea with pallor and petechiae should raise concern about the possibility of hemolytic uremic syndrome. Fever for > 5 days with evidence of mucosal inflammation and rash should prompt consideration of and further evaluation for Kawasaki disease.
Testing
For most children, the history and physical examination are sufficient for diagnosis. Testing is targeted at potential life threats; it includes Gram stain and cultures of blood and cerebrospinal fluid for meningococcemia; complete blood count, renal function tests, and stool tests for hemolytic uremic syndrome).
Treatment of Rash in Infants and Young Children
Treatment of rash is directed at the cause (eg, antifungal cream for candidal infection).
Pruritus in infants and children can be lessened by oral antihistamines:
Some common adverse effects of antihistamines include dry mouth, drowsiness, dizziness, nausea and vomiting, restlessness or moodiness (in some children), urinary hesitancy, blurred vision, and confusion.
Key Points
Most rashes in children are benign.
For most rashes in infants and children, the history and physical examination are sufficient for diagnosis.
Children with rash due to serious illness typically have systemic manifestations of disease.