Medicine in pictures: Mystery childhood rashes

While some childhood viral exanthems are characteristic, others may elude exact diagnosis

Childhood viral infections may cause specific patterns of exanthems that enable a clinical diagnosis of the causative virus.

Examples include chickenpox, herpes zoster, herpes simplex variants, erythema infectiosum, mollusca, and hand, foot and mouth disease.

Many viral infections, however, cause a non-specific, non-diagnostic pattern.

In these cases, the same pattern of exanthem may be caused by different viruses or, conversely, the same virus may produce different patterns of exanthem.

Viruses in this category include enteroviruses (the most common cause in Australian children), adenoviruses, hepatitis A and B, Epstein—Barr virus, cytomegalovirus, and human herpes viruses 6 and 7.

Common non-specific viral exanthem patterns include the following:

Macular exanthems

These are usually very widespread and are difficult to differentiate from drug allergies