Mucocutaneous disease Flashcards
What is a macule / macular lesion (3)
Circumscribed flat lesion
Not elevated
Not palpable
What is a papule / papular lesion (3)
Circumscribed raised lesion
Raised
Palpable
What is a blister? (2)
A fluid filled sac within or below epithelium
What is a vesicle + example (3)
A small blister <5mm diameter
e.g. Herpes simpex vesicles
What is a bulla + example (3)
A large blister >5mm diameter
E.g. pemphigus/ pemphgoid
Describe erosive lesions (3)
Marked thinning / partial loss of epithelium But with a thin epithelial covering of the connective tissue Usually looks red and is very sensitive
Describe an ulcerative lesion (3)
Localised loss of entire thickness of epithelium Exposes underlying connective tissue Usually painful
What are the autoimmune bullous diseases and what type of hypersensitivity are they? (4)
Pemphigus
Pemphigoid
Dermatitis herpetiformis
-type II hypersensitivity
Types of mucocutaneous disease (4)
Autoimmune bullous disease
Epidermolysis bullosa congeita (congital anomaly)
Erythema multiforme (type III/ IV hypersensitivity)
Oral luchen planus and lichenoid reactions (type IV hypersensitivity)
Types of autoimmune bullous disease (3)
Pemphigus
Pemphigoid
Dermatitis herpetiformis
Features of autoimmune bullous disease (3)
Organ specific
Antibody-mediated (type II hypersensitivity)
Autoimmune diseases
Epidemiology of pemphigus (3)
Incidence 0.5-3.2 per 100,000
Main age group: 40-60 years
Male to female ratio = 1:1
What is pemphigus (1)
Organ specific autoimmune disease targeting skin and oral mucosa
Oral features of pemphigus (4)
Mouth involved in most cases, and is the only site involved in over half of cases
Palate, buccal mucosa and gingivae are most commonly affected
Bullae are short lived in mouth and on the skin
Large shallow non-healing ulcers are typical
Nikolsky’s sign (2)
Used in diagnosis of pemphigus
Top layers of skin slip away from lower layers when rubbed
Pathogenesis of pemphigus (3)
Circulating autoantibodies against building proteins that keep epithelial cells together
Binding protein - part of desmosomal complex, usually desmoglein3 (sometimes desmoglein 1 as well)
Autoantibody binds to desmoglein3 leading to epithelial cells separation (acantholysis) and formation of an intra-epithelial bulla
Cells in pemphigus (1)
Tzank cells
Investigations for pemphigus (5)
Biopsy of para-lesional and / or normal tissue
Send tissue to lab fresh or frozen (do not fix)
Routine histology
Direct immunofluorescence staining: used to detect whether autoantibodies are present in the patient’s tissue
Also send blood sample for indirect immunofluorescence, used to detect circulating autoantibodies
Immunofluorescence - pemphigus (2) **
Positive direct immunofluorescent staining of keratinocytes (fish net
pattern)
Autoantibodies (IgG) target Desmoglein 3 in the desmosomes that join keratinocytes