Erythema Flashcards
What is erythema nodusum?
Panniculitis (inflammation of subcutaneous fat tissue) presenting as red or violet subcutaneous nodules.
What is the aetiology of erythema nodusum? (x5)
- INFECTION: bacterial (streptococcus, TB, Yersinia, Chlamydia, leprosy), viral (EBV), fungal (histoplasmosis, blastomycosis), protozoal (toxoplasmosis)
- SYSTEMIC DISEASE: sarcoidosis, IBD, Behcet’s disease
- MALIGNANCY: leukaemia, Hodgkin’s disease
- DRUGS: sulphonamides, penicillin, OCP
- PREGNANCY
What is the pathophysiology of erythema nodusum?
Delayed hypersensitivity reaction to antigens associated with serum macrophage activation and immune complex deposition in the subcutaneous fat.
What is the epidemiology of erythema nodusum: Age? Gender?
Peak age between 20 and 30. Women 3 times more likely to be affected.
What are the signs and symptoms of erythema nodusum? (x4)
- Tender red/violet nodules most commonly bilaterally over the shins, and uncommonly on the thighs, upper extremities, buttocks and face
- Low-grade pyrexia
- Arthralgia
- Occasionally, nodules are associated with extravasated blood resulting in purpura
What are the investigations for erythema nodusum? (x4)
- BLOOD: anti-streptolysin-O titre (measures antibodies against streptococcus) at diagnosis and 2-4 weeks later to assess for preceding streptococcus infection, and other bloods to assess for aetiology
- THROAT SWAB/CULTURE: aetiology
- MANTOUX/HEAF SKIN TESTING: for TB
- CXR: look for hilar adenopathy for sarcoidosis (bilateral), TB and fungal causes (unilateral)
What is erythema multiforme?
Acute hypersensitivity reaction of the skin and mucous membranes.
What is the aetiology of erythema multiforme? (x6)
- DRUGS: sulphonamides, penicillin, OCP
- VACCINES
- INFECTION: viral (HSV, EBV, adenovirus), bacterial (Mycoplasma pneumoniae, Chlamydia), fungal (Histoplasmosis)
- INFLAMMATORY: rheumatoid arthritis, SLE, sarcoidosis, UC
- MALIGNANCY: lymphoma, leukaemia, myeloma
- RADIOTHERAPY
What is the pathophysiology of erythema multiforme? (x3 points)
Theories propose that the disease is a type IV hypersensitivity reaction based in the dermis with (1) degeneration of basal epidermal cells, (2) lymphocytic infiltrate around the blood vessels and underlying the basement membrane, and (3) variable immune complex deposition causing keratinocyte oedema and blistering.
What are the types of erythema multiforme? (x3)
- MINOR: skin lesions with acral (extremities; hands, fingers, toes) distribution without involvement of mucosal sites and involving less than 10% of total body surface
- MAJOR: skin lesions with acral distribution, plus involvement of at least 1 mucosal site and involving LESS than 10% of total body surface
- STEVENS-JOHNSON SYNDROME: atypical lesions that coalesce, resulting in epidermal blistering, necrosis, and sloughing (peeling of skin). Less than 10% of total body surface
What is the epidemiology of erythema multiforme: Age? Gender?
Peak incidence in children and young adults. More common in males.
What are the signs and symptoms of erythema multiforme?
- TARGET LESIONS: acral and symmetrical distribution. Three layers: outer erythematous zone and central blister sandwiching a zone of normal skin tone in between – see photo. Associated with itching or burning. NB: some lesions may lack the clearance zone of normal skin.
- Mucosal erosions, blisters and crusting: painful and tender
- Non-specific prodromal symptoms of URTI common
What is the disease course of erythema multiforme?
Commonly recurs and self-limiting
What are the additional signs and symptoms of Stevens-Johnson syndrome? (x2)
Systemic symptoms such as sore throat, cough, fever, headache, arthralgia, diarrhoea. Also associated with shock
What is the difference between pain and tenderness?
Tenderness is pain on palpation; pain is without touching.
