Erythema Multiforme

Question 1

What is erythema multiforme?

Answer 1

A type 4 hypersensitivity reaction (can be triggered by HSV and drug reactions) which causes widespread oedema and fluid collection within the epithelium.
Results in blister formation
Mostly occurs in young adults

Question 2

What are the presenting signs and symptoms of EM?

Answer 2

Acute condition

Diffuse mucosal erythema, painful erosions and bullae affecting mainly the lips, bucal mucosa and labial mucosa.
Often haemorrhagic crusting of lips.
Lesions appear over 3-5 days and heal in 2-3 weeks without scarring

Skin lesions- target like appearance (symmetrical)

Question 3

What is the most common precipitar of EM?

Answer 3

HSV infection

Question 4

What is the pathogenesis of EM?

Answer 4

Immune complex mechanisms involving antigen antibody reactions that target small blood vessels in the skin or mucosa.

Question 5

What are the histology findings of EM?

Answer 5

Intercellular and intracellular oedema of the overlying epithelium, focal micro vesicle formation, generalised diffuse infiltrate

Question 6

How should recurrent EM be treated?

Answer 6

Antiviral therapy (6 month trial of aciclovir 400mg 2x daily) - to prevent recurrent HSV associated EM

Otherwise, symptomatic treatment