Erythema Nodosum

Question 1

What is erythema nodosum?

Answer 1

Inflammation of subcutaneous fat on the shins (panniculitis) causing tender, erythematous nodules and plaques on the anterior shins.

Caused by hypersensitivity reaction but in over half patients there is no identifiable causes.

Question 2

Triggers/underlying conditions associated with erythema nodosum

Answer 2

hypersensitivity reaction

infections:
- strep throat infection (pharyngitis)
- gastroenteritis
- mycoplasma pneumoniae
- TB
(pregnancy)

inflammatory:
- IBD
- sarcoidosis
- Behect’s disease

medication:
- COCP, NSAIDs
- antibioics (sulphonamides, penicillin)

malignancies:
lymphoma, leukaemia

Question 3

presentation of erythema nodosum

Answer 3

prodrome:
arthralgia (ankles, knees)
malaise
fever (1-3/52 before onset of rash)

rash:
red and inflamed subcutaneous nodules across both shins that are raised, painful and tender and can appear as bruises.
warm erythematous subcutaenous nodules and plaques
brightred then fades to a dusky blue / urple

Question 4

investigation for erythema nodosum

Answer 4

bedside:
- clinical diagnosis
- urine pregnancy test (hCG)

bloods:
- FBC, CRP, ESR
- MC+S (ASOT swab if strep infection)
- tuberculin skin test / interferon gamma release assay (IGRA) if TB

imaging:
- CXR if sarcoidosis, TB, mycoplasma, lymphoma

+ ACE, calcium (sarcoidosis)
+ serology: HSV, EBV, hep A/C, HIV
+ stool cultlure- ova, parasites
+ colonoscopy- IBD
+ excisional skin biopsy

Question 5

how is erythema nodosum managed?

Answer 5

investigate for cause
conservatively- rest, analgesia, steroids to settle inflammation
resolves in 6 weeks

Question 6

presentation of erythema nodosum

Answer 6

red and inflamed subcutaneous nodules across both shins that are raised, painful and tender and can appear as bruises.

Question 7

dermatitis herpetiformis

Answer 7

rash, intermitten diarhoea, anti-endomysial antibody, granular IgA deposits, mild anaemia

associated with coeliac disease

symptoms- intensely itchy papule or vesicles.

mx- gluten free diet

Question 8

pemphigus vulgaris

Answer 8

autoimmune disease. blistering and erosions on the skin / mucuous membranes.

IgG autoantibodies to desmolgein
??? (see pic on phone)

Question 9

bullous phemigoid

Answer 9

sub epidermal splitting
blisters are tense and less easily ruptured
mucous membranes not commonly involved