Erythema Flashcards
What causes erythema ab igne?
over exposure to infrared radiation.
A typical history would be an elderly women who always sits next to an open fire.
Features of erythema ab igne
- reticulated, erythematous patches with hyperpigmentation and telangiectasia.
Typical patient presenting with erythema ab igne
- elderly women who always sits next to an open fire.
What may develop if the cause of erythema ab igne is not removed?
May develop SCC
What is erythema multiforme?
- hypersensitivity reaction
- most commonly triggered by infections
Features of erythema multiforme
- target lesions
- initially seen on the back of the hands / feet before spreading to the torso
- upper limbs > lower limbs
- pruritus usually mild
Causes of erythema multiforme
- Viral - herpes simplex virus
- idiopathic
- bacteria: Mycoplasma, Strep
- Drugs: penicillin, sulphonamides, carbamazepine, allopurinol, NSAIDs, oral contraceptive pill,
- Connective tissue disease e.g. SLE
- Sarcoidosis
- Malignancy
What feature changes a diagnosis to erythema multiforme MAJOR?
Mucosal involvement
What is erythema nodosum?
- inflammation of subcutaneous fat
Features of erythema nodosum
- tender, erythematous, nodules
- MAINLY shins
- may also occur elsewhere (e.g. forearms, thighs)
How long does it normally take erythema nodosum to resolve? Do the lesions scar?
6 weeks
no scarring
Causes of erythema nodosum
infection
- strep, TB
systemic disease
- sarcoid, IBD, Behcet’s
malignancy/lymphoma
drugs
- penicillins, sulphonamides, COCP
Pregnancy
Features of erythrasma
- asymptomatic
- flat, slightly scaly, pink or brown rash
- usually found in the groin or axillae
What causes erythrasma
-overgrowth of the diphtheroid Corynebacterium minutissimum
What investigation findings can help diagnose erythrasma?
Examination with Wood’s light
= coral-red fluorescence.
Treatment of erythrasma
- Topical miconazole or antibacterial
- Oral erythromycin if extensive infection
What is the meaning of erythroderma?
When 95% skin involved in a rash
Causes of erythroderma
eczema
psoriasis
drugs e.g. gold
lymphomas, leukaemias
idiopathic
Nickname for erythroderma
“Red Man” syndrome
What can cause acute erythrodermic psoriasis? How should these patients be managed?
withdrawal of systemic steroids.
*admit to hospital
