Erythema Nodosum Flashcards
1
Q
A
2
Q
How long does erythema nodosum usually last for?
A
6 weeks
3
Q
What is the pathophysiology of Erythema nodosum?
A
An inflammation of subcutaneous fat
4
Q
The lesions scar?
A
No they don’t.
5
Q
Where does it usually occur?
A
Shins (but can occur on thighs and forearms)
6
Q
What can cause erythema nodosum?
A
- Infection: streptococci, TB, brucellosis
- Systemic disease: sarcoidosis, inflammatory bowel disease, Behcet’s
- Malignancy/lymphoma
- Drugs: penicillins, sulphonamides, combined oral contraceptive pill, aspirin, codeine.
- Pregnancy
7
Q
A lady presents with erythema nodosum, which test is the best to order?
A
All these tests may have a place but a chest x-ray is important as it helps exclude sarcoidosis and tuberculosis, two important cause of EN.
8
Q
What investigations should be done for EN?
A
-
First test - A throat swab for streptococcus (although it may well be negative, even with streptococcal disease.)
- Anti-streptococcal O (ASO) titre may be more helpful,
- Serum anti-deoxyribonuclease B (AntiDNAseB) antibodies and anti-hyaluronidase levels are more sensitive than ASO titre in cases of recent serious streptococcal skin infection.
-
Bloods
- FBC and ESR
- Sarcoidosis - calcium and angiotensin-converting enzyme (ACE).
- Cultures and Blood film.
- Stool specimen - Y. enterocolitica, Salmonella spp. & Campylobacter spp.
- CXR - bilateral hilar lymphadenopathy (BHL) in sarcoidosis, unilateral or asymmetrical adenopathy in malignancy, or evidence of pulmonary tuberculosis.
- Intradermal skin tests & Excisional biopsy may be helpful where the diagnosis is in doubt.
9
Q
Which drug is most likely to cause EN?
- Ciprofloxacin
- Co-trimoxazole
- Ketoconazole
- Metronidazole
- Trimethoprim
A
- Co-trimoxazole - because it has trimethoprim AND sulfamethoxazole which is a sulphonamide. Sulphonamides are well known to cause EN.
