Pityriasis alba: A common, benign condition in children characterized by small, round, hypo-pigmented patches on the face, often accompanied by a fine scale. It's more noticeable in children with darker skin and is exacerbated by sun exposure, which fits the description of a rash on exposed areas.

Contact dermatitis: This could be due to an allergic reaction or irritant exposure to substances like plants, soap, or sunscreen on the skin. It presents as red, itchy, and sometimes blistered skin.
Erythema multiforme: Although it can be associated with systemic symptoms, a mild form might present with only skin manifestations. It's characterized by target lesions and can be triggered by infections or medications.
Viral exanthems (e.g., roseola, fifth disease): While these conditions often come with systemic symptoms, mild cases might not. They cause rashes that can appear on exposed areas among other places.

Meningococcemia: Although rare, this condition is life-threatening and can present with a petechial or purpuric rash that might initially appear on exposed areas. It's crucial to consider this diagnosis, especially if there's any suspicion of systemic infection.
Rocky Mountain spotted fever: This tick-borne illness can cause a rash on the wrists, ankles, palms, and soles, which might initially appear on exposed areas. It's critical to identify and treat promptly due to its potential severity.

Leukocytoclastic vasculitis: A condition characterized by inflammation of the blood vessels, which can cause a purpuric rash. It's less common in children and might require specific diagnostic tests.
Kawasaki disease: While it typically presents with systemic symptoms, early stages might not. It's characterized by fever, rash, swelling of hands and feet, and other specific criteria. The rash can appear on exposed areas among others.