Erythema Nodosum

Question 1

What is erythema nodosum?

Answer 1

panniculitis (inflammation of subcut fat tissue) presenting as red or violet subcutaneous nodules

Question 2

Describe the pathophysiology of erythema nodosum

Answer 2

Delayed hypersensitivity reaction to antigens associated with various infectious agents, drugs + diseases

Question 3

What acronym lists the causes of erythema nodosum?

Answer 3

Leprosy, Lymphoma, Leukaemia
OCP + Pregnancy
Sarcoidosis, Sulphonamides, Pencillins
TB, Toxoplasmosis
Bechets
UC + Crohn's
Salmonella, Yersinia, Strep
Histoplasmosis

Question 4

Describe the epidemiology of erythema nodosum

Answer 4

Usually affects YOUNG ADULTS

F > M

Question 5

List 5 signs and symptoms of erythema nodosum

Answer 5

Tender red or violet dome-shaped nodules bilaterally on both shins (+/- thighs or forearms)
Fatigue
Fever
Arthralgia
Signs + symptoms of underlying CAUSE e.g. GI sx

Question 6

What investigations are used in erythema nodosum?

Answer 6

Bloods 
Anti-streptolysin-O titres (streptococcal infection) 
FBC/CRP/ESR (infection/ inflammation)
U+Es  
Serum ACE (raised in sarcoidosis) 
Throat swab + cultures  
Mantoux test: for TB  
CXR: check for bilateral hilar lymphadenopathy or other evidence of TB, sarcoidosis or fungal infections

Question 7

Describe the nodules in erythema nodosum

Answer 7

Erythematous
Firm
Deep nodules or plaques
Painful on palpation
Mainly localized on extensor surfaces of the legs