Rash

Polymorphic light eruption is a common photosensitivity disorder which particularly affects young females. The skin shows 'hardening', such that areas frequently exposed to the sun, such as the face and hands, may not be affected whilst newly exposed sites are most severely affected. The rash often develops after a few days of sun exposure and is most severe at the beginning of the summer and improves at the end of the summer as the skin 'hardens'.

Systemic lupus erythematosus is a photoaggravated disorder in which the face is usually affected.

Photoallergic contact dermatitis can occur due to sunscreen allergy. A rash would appear at all sites where sunscreen had been applied and subsequently exposed to the sun.

Scabies is not photoaggavated.

Patients with xeroderma pigmentosum describe easy burning after minimal sun exposure. They subsequently develop freckling, chronic solar damage and skin tumours.

Chickenpox, which is clearly very much the more common disease, causes a rash which crops, is typically central, and does not affect the hands and feet.

Smallpox rash is more distal and causes deep lesions which leave scars (typically on the face).