Erythema Nodosum is a probable high yield question on KFP as dermatology is something that lends itself to this format, with picture -> direct questions.
Betty is a 25 year old girl who presents with a sore throat and painful lumps on shins as seen below, that have continues for 10 days. She also has fevers, malaise, joint pain.
What is the most likely diagnosis?
What is the likely cause of this diagnosis?
What investigations would you perform?
What treatment would you institute?
Causes of erythema nodosum
- Pregnancy – second trimester
- Strep throat infection
- Bacterial infections,TB, Yersinia, Chlamydia, histoplasmosis, leprosy, Hep B, Mycoplasma pneumonia,
- IBD – Crohns or UC
- Sarcoidosis
- Drugs – sulphonamides, COCP
- Malignancies – lymphoma and leukaemia
Investigation in Erythema Nodosum
- Throat swab for strep – first test
- ASOT
- FBC
- ESR
- UEC
- LFT
- CXR and ACE – Sarcoidosis, TB, hilar lymphadenopathy
- Stool for Yarsinia, salmonella, campylobacter
- Biopsy usually not needed but if done deep and include fat
- QFG – TB
Treatment of Erythma Nodosum
- Treat infection if cause
- Bed rest
- Leg elevation
- NSAIDS – no other drugs normally needed
- If symptoms severe then Pred 25mg daily 2 weeks then taper – use with caution and only if non infective cause
- Compression bandages
- TED stockings
- Oral potassium iodide for difficult cases
