Pathology Flashcards
What are the four main inflammatory skin patterns?
Give an example of each.
- Spongiotic - intraepidermal oedema e.g. eczema (see Dr Brown’s eczema lecture)
- Psoriasiform - elongation of the rete ridges e.g. psoriasis
- Lichenoid - basal layer damage e.g. lichen planus and lupus
- Vesiculobullous-blistering e.g. pemphigoid, pemphigus and dermatitis herpetiformis
What are the two main pathological problems in psoriasis?
Acanthosis of the epidermis
Parakeratosis (nuclei persist in the surface keratin)
What is the Koebner phenomenon?
New lesions of psoriasis arise at sites of trauma
What is the genetic influence in psoriasis?
Unclear - associated with specific HLA types
Which inflammatory cells are there in psoriasis?
No infection, but neutrophils gather in the epidermis, suggests that complement is activated in psoriasis which draws the neutrophils.
What is the problem in erythrodermic psoriasis?
Patients die from oozing fluid from the skin which causes metabolic problems
What is psoriasiform?
Histology – the ridges are elongated and fused; often become clubbed at the base – known as psoriasiform. May also get neutrophils in the corneal layer.
Which layer of the skin is affected in lichenoid disorders?
Basal layer of epidermis
What is the main clinical feature in lichen disorders?
Itchy flat topped violaceous papules
- Irregular sawtooth acanthosis
- Hypergranulosis and orthohyperkeratosis
- Band-like upper dermal infiltrate of lymphocytes
- Basal damage with formation of cytoid bodies
Which disease is this?
Lichenoid disorder
Immunobullous disorders
- Main clinical feature?
- Give three examples
Blisters
- Pemphigus
- Bullous pemphigoid
- Dermatitis herpetiformis
Pemphigus
- What type of disease?
- Epidemiology?
- Histology?
- Severity?
- Treatment?
- Types?
- Most common type?
- Rare autoimmune bullous disease
- Sex incidence is equal, usually middle -age
- Loss of integrity of epidermal cell adhesion
- Variable severity - occasionally fatal
- Responds to steroids
- Pemphigus has four distinct types which are separable clinically and histologically.
The most common is pemphigus vulgaris.
Pemphigus vulgaris
- Which antibody?
- What forms on cell surface?
- Disruption of which structures?
- End result?
- IgG auto-antibodies made against desmoglein 3
- Immune complexes form on cell surface
- Disruption of desmosomes
- End result is ACANTHOLYSIS
Pemphigus vulgaris
- Which areas of the body are affected?
Scalp, face, axillae, groin, trunk. It may affect mucosa e.g. mouth, resp.tract. Extensive mucosal involvement may be fatal. It produces fluid filled blisters which rupture to form shallow erosions.
What pathology is common to ass variants of pemphigus?
Acantholysis = lysis of intercellular adhesion sites
What causes the bulla is pemphigus vulgaris?
Basal cells stick onto the basement layer, but above this they fall apart, causing a bulla
What test is used for pemphigus vulgaris and what does it show?
An anti-IgG antibody with a fluorescent tag locates bits of IgG in the skin. When UV light is shone on the skin, IgG shows up
Bullous pemphigoid
- Which layer of skin is affected
- Immunology?
- Clinical sign?
- Pathology difference from PV?
Bullous is SUB EPIDERMAL, and attacks the hemidesmosomes. Complement is activated between basal layer cells and basement membrane – epidermis floats off, causing a blister.
There is no evidence of acantholysis.
What is the pathophysiology of bullous pemphigoid?
Circulating antibodies (IgG) react with a major and/or minor antigen of the hemidesmosomes anchoring basal cells to basement membrane. The result is local complement activation and tissue damage.
What does immunofluorescence show in bullous pemphigoid?
What do older lesions show?
Immunofluorescence shows linear IgG + complement deposited around the BM.
Older lesions of pemphigoid show re-epithelialisation of their floor, mimicking pemphigus vulgaris.
Dermatitis herpetiformis
- What type of disease
- Associated with which disease?
- Genetics?
- Clinical signs?
- Hallmark feature?
- Autoimmune bullous disease
- Strong association with coeliac disease
- Associated with HLA-DQ2 haplotype
- Intensely itchy lesions-symmetrical
- Elbows, knees and buttocks-often excoriated
- Hallmark is papillary dermal microabscesses
Which antibody is dermatitis herpetiformis associated with?
IgA
Describe the pathology of acne
- Androgens at puberty
- Androgen sensitivity of sebaceous glands
- Keratin plugging of pilosebaceous units
- Infection with anaerobic bacterium corynebacterium acnes
