Uriticaria

- Pruritic round pink to flesh colored plaques of varying sizes

- More common in patients with atopy

- Can be triggered by medications, foods, and allergens

Fixed drug eruption

- Solitary, round, well demarcated, bright red to dusky erythemic macules or plaques

- Can form bullous lesions

- Typically blister, crust or desquamate

- Associated with pruritis and burning

- Continue to reoccur in same place with subsequent exposure

- Genitalia and perianal areas are most common

- Can be generalized

Stevens-Johnson syndrome

- Atypical erthemic, dusky red target lesions

- or macular pruritic lesions

- associated with skin tenderness and burning

- Lesions coalesce

- Erosions and bullous lesions may be present on mucosal surfaces

- Central face, trunk, and proximal extremities

- Mucocutaneous

- Eye involvement possible

Erythema multiforme

- Classically, erythemic, dusky red target lesions

- Erythemic macules, papules, lesions resembling urticarial, vesicles, and bullae are also common

- Pruritis and burning sensation

- Bullous lesions and erosions found in the oral area

- Symmetric on distal extremities

- palmar and plantar surface

- Erythemic, pruritic, urticarial like papules that coalesce into plaques, eventually forming bullous lesions

- Once ruptured, an eroded base is left behind that will crust

- Nikolsky sign negative

- Typically seen in adults over age 60

- Skin folds, flexural surfaces, dependent areas

- Can be generalized