Dermatology 🧖🏽♀️ Flashcards
MLA conditions and preperation
Erythema multiforme
Hypersensitivity reaction that is most commonly triggered by infections.
It may be divided into minor and major forms.
Typically appears like target lesions on the skin.
Features of Erythema multiforme
-target lesions
-initially seen on the back of the hands / feet before spreading to the torso
-upper limbs are more commonly affected than the lower limbs
-pruritus is occasionally seen and is usually mild
Causes of erythema multiforme
-viruses: herpes simplex virus (the most common cause), Orf (Parapox virus)
-idiopathic
-bacteria: Mycoplasma, Streptococcus
-drugs: penicillin, sulphonamides, -carbamazepine, allopurinol, NSAIDs, oral -contraceptive pill, nevirapine
-connective tissue disease e.g. Systemic lupus -erythematosus
-sarcoidosis
-malignancy
Erythema multiforme major
The more severe form, erythema multiforme major is associated with mucosal involvement.
Who gets erythema multiforme commonly
most common in young adults (aged 20–40 years) with a modest predominance in males. There is no association with race.
HLA-DQB1*0301 allele associated with herpes
Medications which may trigger erythema multiforme (4)
Antibiotics (including erythromycin, nitrofurantoin, penicillins, sulfonamides, and tetracyclines)
Anti-epileptics
Non-steroidal anti-inflammatory drugs
Vaccinations (most common cause in infants).
Conditions associated with erythema multiforme
Inflammatory bowel disease
Hepatitis C
Leukaemia
Lymphoma
Solid organ cancer malignancy.
Clinical features of ertythema multiforme
fatigue,
malaise,
myalgia,
or fever.
These likely represent the course of precipitating illness rather than true prodrome.
Serious complications of erythema multiforme
Keratitis
Conjunctival scarring
Uveitis
Permanent visual impairment.
What tests should be carried out if erythema multiforme is suspected
Complete blood examination
Liver functions tests
ESR
Serological testing for infectious causes
Chest x-ray.
Skin biopsy with histopathology and direct immunofluorescence
Treatment of erythema multiforme
- self limiting condition
- cease medication which causes
- prednisone for mucosal disease
- antiviral therapy aciclovir
Erythema nodosum
inflammatory disorder affecting subcutaneous fat. It most commonly presents as bilateral tender red nodules on the anterior shins
Who gets erythema nodosum
Erythema nodosum can occur in all ethnicities, sexes, and ages, but is most common in women between the ages of 25 and 40
It is 3–6 times more common in women than in men except before puberty when the incidence is the same in both sexes
Infective causes of erythema nodosum? (6)
- hypersensitivity reaction of unknown cause in 55%
-usually associated with drugs, infection or malignancy
Throat infections (streptococcal disease or viral infection)
Primary tuberculosis (TB), a rare cause in New Zealand
Yersinia infection; this causes diarrhoea and abdominal pain
Chlamydia infection
Fungal infection: histoplasmosis, coccidioidomycosis
Parasitic infection: amoebiasis, giardiasis
Viral and bacteria diseases which are associated with erythema nodosum
-HSV
- viral hepatitis
-HIV
- campylobacter infection
- Salmonella infection
Drugs which cause erythema nodosum (8) SHTEN
Sulfonamide
Hormonal
Tetracycline
ACE inhibitors
NSAIDs
Oral contraceptive
Non-steroidal anti-inflammatory drugs
Bromide
Salicylate
Iodide
Gold salt
Inflammatory diseases which cause erythema nodosum
Inflammatory bowel disease (ulcerative colitis or Crohn disease)
Sarcoidosis (11–-25%); X-ray shows bilateral hilar adenopathy in Löfgren syndrome
Malignancy
Lymphoma
Leukaemia
Behçet disease
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Pregnancy
Investigations for erythema nodosum
Complete blood count with differential, C-reactive protein levels (infectious and inflammatory causes)
Chest X-ray (tuberculosis and sarcoidosis)
Throat swab and anti-streptolysin O and streptodornase serology (streptococcal infection)
Viral serology (preferably two samples at four-week intervals)
Stool culture and evaluation for ova and parasites in patients with gastrointestinal symptoms
Mantoux test or QuantiFERON gold (tests for TB).
Deep incisional or excisional skin biopsy.
Septal Panniculitis
Various forms of scleroderma
Medium vessel vasculitis, for example, due to polyarteritis nodosa in which there are tender subcutaneous nodules associated with ulceration, necrosis, livedo racemosa, fever, joint pain, myalgia, and peripheral neuropathy
Necrobiosis lipoidica
Eosinophilic panniculitis
Rheumatoid nodule.
Guttate psoriasis
Distinct variant of psoriasis that is classically triggered by streptococcal infection (pharyngitis or perianal)
More common in Childern and adolescents
Features of guttate psoriasis
Tear drop papules on the trunk and limbs
gutta is Latin for drop
pink, scaly patches or plques of psoriasis
tends to be acute onset over days
Typically triggered by Streptococcal infection
What is the managment of guttate psoriasis
most cases resolve spontaneously within 2-3 months
there is no firm evidence to support the use of antibiotics to eradicate streptococcal infection
topical agents as per psoriasis
UVB phototherapy
tonsillectomy may be necessary with recurrent episodes
Prodome (guttate vs Pityriasis rosea)
Many patients report recent respiratory tract infections but this is not common in questions
Appearance (Guttate vs Pityriasis rosea)
‘Tear drop’, scaly papules on the trunk and limbs
Herald patch followed 1-2 weeks later by multiple erythematous, slightly raised oval lesions with a fine scale confined to the outer aspects of the lesions.
May follow a characteristic distribution with the longitudinal diameters of the oval lesions running parallel to the line of Langer. This may produce a ‘fir-tree’ appearance