Erythema Multiforme

Question 1

Define erythema multiforme.

Answer 1

Erythema multiforme (EM) is typically an acute, self-limiting but often relapsing, mucocutaneous inflammatory condition. It is a hypersensitivity reaction associated with certain infections, vaccinations, and, less commonly, medications.

Question 2

Explain the aetiology/risk factors of erythema multiforme.

Answer 2

Prior occurrence
Herpes simplex virus (HSV) infection
Mycoplasma pneumonia

Question 3

Summarise the epidemiology of erythema multiforme.

Answer 3

The incidence of EM is not known, although it is considered to be relatively common. Peak incidence occurs in the second and third decades, and it rarely occurs in patients under 3 or over 50 years of age.

Question 4

Recognise the presenting symptoms of erythema multiforme. Recognise the signs of erythema multiforme on physical examination.

Answer 4

Target lesions of the extremities
Recurrent disease
Mucosal erosions
Rapid onset of lesions
Self-limiting course
Clustered vesicles on an erythematous base
Rhonchi, rales, and/or wheezes

Question 5

Identify appropriate investigations for erythema multiforme and interpret the results.

Answer 5

FBC
Serum electrolytes
Herpes simplex virus (HSV) serology
Rapid PCR
Cold-haemagglutination serology
M pneumoniae titres
CXR