Drug related

• Type I or Type IV hypersensitivity
• Eosinophils will be present

Photo-induced or photosensitive

• Reaction to UV light
• Well defined edge e.g. cut-off collar
• Patients often atopic
• Can also occur secondary to photosensitising drugs

Lichen simplex

• Chronic itchy skin disorder characterised by well demarcated, erythematous patches, and plaques of thickened leathery skin

Stasis (varicose) dermatitis

Aetiology

• This is eczema associated with chronic venous insufficiency (venous hypertension), usually affecting the gaiter area
• Increased hydrostatic pressure of the blood results in extravasion of RBCs

Clinical features

• Associated skin change include venous ulcers, lipodermatosclerosis, and hemasiderosis

Management