Vesiculobullous Lesions 2 Flashcards
What is bullous lichen planus?
Condition with many of the features of pemphigoid superimposed on lichenoid histological pattern
What is pemphigoid?
Sub epithelial antibody attack resulting in persistent thick walled blisters (can be clear or blood filled)
How does damage to epithelium occur in pemphigoid?
Antibodies cause separation of epithelium from connective tissue at basement membrane by targeting hemi-desmosomes
-> full thickness of epithelium is released with fluid and inflammatory exudate filling space
Where does the fluid in pemphigoid blisters come from?
Fluid comes from connective tissue
As a result of immunological damage- RBCs may go into fluid giving it blood filled appearance
What are the types of pemphigoid?
Bullous Pemphigoid - skin
Mucous Membrane Pemphigoid – all mucous membranes affected (eye, genital, oral)
Cicatritial Pemphigoid – subset of mucous membrane- presence of scarring (different epitopes on same antigen involved in generation of lesion)
How should a biopsy of pemphigoid be carried out?
Take from peri-lesional tissue to aid diagnosis
-> as it is impossible to guarantee that epithelium will remain attached to underlying mucosa (characteristic features should still be seen)
How does pemphigoid appear histologically?
Split at junction of epithelial and connective tissue due to damage of heme-desmosomes at BM
How is pemphigoid tested for?
DIF is best- immunofluorescent staining can be seen along BM (Linear basement membrane staining)
-> fluorescein tag is attached to antibody which binds to circulating pemphigoid antibody which binds to antigen in BM
Antibody to which stain is bound can be c3 (usually always involved), IgG, IgM and IgA
-> Disease may behave differently depending on antibody triggering issue
How does staining appear in dermatitis herpetiformis appear?
Granular deposits of C3 and IgA seen
-> non linear like pemphigoid
What condition is DH associated with?
Coeliac
What can scarring of mucosa due to pemphigoid result in?
Narrowing of oro-pharynx (can be invisible)
Symblepharon- scarring of conjunctiva can bind eye surface to eyelid (restricts eye movement- dipoplia)
-> checked regularly by optician/ophthalmologist to see if this is developing
Which other healthcare professionals are involved in managing pemphigoid (esp circatritial)
Ophthalmologist
Dermatologist
Oral physician
How is pemphigoid managed?
Immune suppressants to prevent antibody generation causing disease:
Steroids
IMD- azathioprine, mycophenolate, dapsone and biologics
How does damage in pemphigus occur?
Circulating antibody is formed against desmosome tissue which holds cells together (not hemidesmosomes)
-> these cells lose adhesion to each other as a result
Intraepithelial bullae form- there may only be a few layers of cells above or around lesion but fluid fills spaces causing drift (epithelium is initially thinned but is then completely lost)
What is the main difference between pemphigus and pemphigoid?
In pemphigus- intact bulla are rarely seen
-> presents as areas of surface loss and mucosal erosion
What areas are affected by pemphigus, what is the usual sequence?
Often presents orally first, can take up to 3 years for skin lesions to present
-> Skin also suffers from erosive loss of cell structure and widespread loss of epithelial covering (fluid loss and infection risk)
Which groups are more likely to suffer from pemphigus?
Over 50s
Females
Ashkenazi jew population
What are the histological features of pemphigus?
Loss of epithelium and shedding of epithelial layer
Supra-basal (split occurs above basement membrane)
Tzank cells are characteristic
What gives the basket weave appearance when immunofluorescence of pemphigoid is carried out?
Antibody attacks desmosomes which are present on many surfaces of epithelial cells giving immunofluorescent surrounding
-> different from linear BM staining in pemphigoid
What is the commonest form of pemphigus?
Vulgaris
Which antibodies are commonly identified in pemphigus vulgaris?
C3 and IgG
How does pemphigus present clinically?
Erosions rather than blisters (same in skin and mouth)
-> Intact bullae are rare- thin walled intra-epithelial blisters
Can affect any part of oral mucosa
Appears like desquamative gingivitis in mouth- loss of epithelial covering OR as area covered with fibrinous exudate
How is pemphigus managed?
High dose of steroids, biologics and immunosuppressants are required to stop erosions and loss of epithelial coverage
-> Biologics are preferred as other medicines put patient at risk of other diseases
Why must pemphigoid and pemphigus be managed by specialists?
They can be fatal
