Mucocutaneous - Vesiculo-bullous disease Flashcards
Macule (macular lesion) features?
Circumscribed flat lesion
Not elevated
Not palpable
Papule (papular lesion) features?
Circumscribed raised lesion
Raised
Palpable
Blister
Fluid filled sac within or below epithelium
Vesicle
Small blister less than 5mm
e.g. herpes simplex virus
Bulla
Large blister more than 5mm diameter
e.g. pemphigus/pemphigoid
Erosion
Marked thinning/partial loss of epithelium
But with a thin epithelial covering of the CT
Usually looks red and is v sensitive
Ulcer
Localised loss of entire thickness of epithelium
Exposes underlying CT
Usually painful
Examples of mucocutaneous disease?
Autoimmune bullous disease - Pemphigus - Pemphigoid - Dermatitis herpetiformis = Type II hypersensitivity
Epidermolysis bullosa congenita = congenital anomaly
Erythema multiforme = type III/IV
Oral lichen planus and lichenoid reactions = type IV
Autoimmune bullous diseases features?
Organ specific
Antibody mediated Type II hypersensitivity
Autoimmune disease
Pemphigus epidemiology?
Incidence 0.5-3.2 per 100,000
40-60 yrs old
1:1 M:F
Organ specific autoimmune disease targeting skin and oral mucosa
Oral features of pemphigus?
Mouth involved in most cases, only site involved in over half of cases
Palate, buccal mucosa and gingivae - most commonly affected
Bullae - short lived in mouth and on skin
Large shallow non healing ulcers are typical
Pathogenesis of pemphigus?
Circulating autoantibodies against binding proteins that keep epithelial cells together (desmosomes). Binding protein- part of the desmosomal complex, usually desmoglein3 (sometimes desmoglein 1 as well). Autoantibody binds to desmoglein3- acantholysis and formation of an intra-epithelial bulla.
Pemphigus histology?
Parakeratinised SS epi
CT under it
Bullae either side has epithelium = intraepithelial bullae
Rounded cells in vesicle fluid = sank cells
Pemphigus investigations?
Biopsy of para-lesional and/or normal tissue
Send tissue to lab fresh
Routine histology - separate biopsy or part of fresh specimen
Direct immunofluorescence staining - used to detect whether autoantibodies are present in the patient’s tissue
Pemphigus immunofluorescence
Positive direct immunofluorescent staining in epithelial cells (fish net pattern)
Autoantibodies (IgG) target desmoglein 3 in the desmosomes that join keratinocytes
Direct immunofluorescence - how does it work?
If pt has pemphigus the autoantibodies are present in the sample
Add in fluorescent labelled anti-human IgG to attach to the autoantibody
When are blood samples needed to investigate pemphigus?
Circulating desmoglein levels
For indirect immunofluorescence
Used to detect circulating autoantibodies
Not used routinely any more