Skin rashes

Question 1

What is erythema multiforme?

Answer 1

Skin eruption characterized by target lesions (maculopapular), due to immune complex deposition in the superficial microvasculature of the skin and oral mucous membrane

Regarded as distinct from Steven Johnson syndrome/ Toxic epidermal necrolysis

Question 2

What are triggers for erythema multiforme?

Answer 2

Infections 90% cases -

• common - HSV, mycoplasma
• uncommon - VZV, parapoxvirus, adenovirus, HIV, CMV, hepatitis viruses

Many drugs have been implicated

Question 3

What is treatment of erythema multiforme?

Answer 3

Antihistamine/ topical corticosteroids for itch

Admission for supportive care

Recurrent erythma multiforme - aciclovir for 6 months

Dapsone/ azathioprine has been trialled for suppression

Usually resolves over 2-3 weeks

Question 4

What is erythema nodosum?

Answer 4

a type of panniculitis, an inflammatory disorder affecting subcutaneous fat. Hyper

It presents as tender red nodules on the anterior shins. Less commonly, they affect the thighs and forearm

Question 5

Who gets erythema nodosum?

Answer 5

Can occur in any sex/ age

Usually female 25-40

Question 6

What are infectious causes of erythema nodosum?

Answer 6

HSV
Hepatitis viruses
HIV

Streptococcal
TB
Chlamydia
Salmonella
Cambylobacter
Yersinia enterocolitica

Histoplasma

Streptococcal most common cause in children
Sarcoidosis most common cause in adults

Question 7

What are non-infectious causes of erythema nodosum?

Drugs
Inflammatory

Answer 7

Pregnancy

Sulfonamide
Amoxicillin
OCP
NSAIDs

IBD
Sarcoidosis (most common cause in adults)
Malignancy
Lympmha
Leukaemia
Behcets

Question 8

What are clinical features or erythema nodosum?

Answer 8

Bilateral erythematous subcutaneous nodules

Joint pain

Fever

Question 9

What investigations are required for erythema nodosum from infection point of view?

Answer 9

HSV viral swab - cold sore/ genital herpes

HIV/ HBV/ HCV

ASO - streptococcal
Throat swab - streptococcal

CXR - TB
IGRA - TB

Stool culture - campylobacter, salmonella, Yersinia entercolitica

Urine - chlamydia

Biopsy of lesion

Question 10

What is management of erythema nodosum?

Answer 10

Analgesia/ NSAIDS

Corticosteroids - if infection/ malignancy excluded

Usually resolves without any complications

Question 11

What are investigations for erythema multiforme?

Answer 11

HSV - viral swab cold sore/ genital lesion (90% cases)

HIV/ HBV/ HCV

Mycoplasma (2nd most common cause)