Histopath Flashcards
Where can the stratum lucidum be found?
Palms and soles
What are the 6 types of inflammatory reaction patterns of the skin?
- Vesiculobullous
- Spongiotic
- Psoriasiform
- Lichenoid
- Vasculitic
- Granulomatous
Describe the underlying pathophysiology of bullous pemphigoid
It is an autoimmune reaction. Anti-hemidesmosomes IgG antibodies and complement attack the stratum basale which causes the whole layer to lift up and attracts eosinophils which release elastase and cause further damage. Fluid builds up and whole epidermis lifts up, forming a tense bulla
How do you diagnose bullous pemphigoid?
Immunofluorescence IgG and C3
You’ll see a band along the basement membrane
Describe the underlying pathophysiology of pemphigus vulgaris
Anti-desmosome antibodies (IgG) attack the connections between keratinocytes and thus the keratinocytes start to free float and fluid collects intraepidermally.
Can use immunofluorescence to demonstrate IgG around the individual keratinocytes
Type 2 hypersensitivity
Describe the underlying pathophysiology of pemphigus foliaceus
Antibodies (IgG related) against the connections in the stratum corneum and hence it comes away. You don’t see bullae in this condition as they are so thin that they tear away after a shor tperiod of time, leaving an excoriated area.
Use immunofluorescence for diagnosis
What is the inflammatory rection pattern seen in eczema called?
Spongiotic - this means that there is oedema/fluid between the keratinocytes
Describe the long term skin changes in eczema
Epidermis starts to get thicker over time - lichenification
Name the inflammatory reaction pattern seen in psoriasis
Psoriasiform
Auspitz’s sign
Seen in psoriasis
Pin point bleeding upon removal of the silvery plaques.
Due to the fact that the epidermis is thinner and corresponds to the tips of the dermal papillae and vessels which are dilated and more prominent.
Koebner phenomenon
Appearance of skin lesions along lines of trauma
Psoriasis
What is the normal transit time from stem cell to keratinocyte and what is it in psoriasis?
Normal - 56 days
Psoriasis - 7 days
Which layer of the epidermis do you lose in psoriasis?
Granulosum
However, epidermis thickens due to high proliferation rate
Munro’s microabscesses
Accumulation of neutrophils within the stratum corneum in psoriasis (cardinal sign)
Useful as it contrasts the eosinophils you see in eczema
Describe the symptoms of lichen planus
Itchy, purpley, red, patches/plaques in the extensor surfaces and distal surfaces
Classic white lines in the mouth - Wickham striae
Wickham striae
Classic white lines in the mouth seen in lichen planus
Describe the underlying pathophysiology of lichen planus
T lymphocytes attack the basal layer of keratinocytes in the epithelium. You can’t see where the epidermis stops and dermis starts as the bottom layer goes through apoptosis. You get a classic band-like inflammation underneat
What is a seborrhoeic keratosis?
One of the commonest benign lesions
Look cauliflowerish, pigmented and all over the place in the elderly
Completely harmless as it is due to keratinocytes proliferating in an orderly manner.
Histologically you may see large windows called keratin horn cysts
Describe the pathophysiology of sebaceous cysts
Epidermis is invaginated and got caught up within the dermis and it produces the keratin
Describe features of a basal cell carcinoma
Central ulceration
Raised pearly rim around the edge
Nicknamed rodent ulcer as it tends to burrow away into the nooks and crannies of the face
Rarely metastasises
Bowen’s Disease
Precancer (SCC)
Basically full thickness dysplasia but has not broken through the basement membrane
What is perineural invasion?
This is when the tumour wraps around a nerve
What causes naevi?
Melanocytes proliferate and acumulate
Describe the 3 types of naevi
1) Junctional - melanocytes in epidermis (younger population)
2) Compound - melanocytes in epidermis and dermis
3) Intradermal -melanocytes in dermis
Intradermal more common as you get older as melanocytes tend to migrate downwards as you get older
What is pagetoid spread?
This is when there is an upward migration of melanocytes which shouldn’t happen (should be migrating downwards and become smaller). This indicates lack of maturity as the size of melanocytes are uniform throughout
When is pagetoid spread normal?
In pregnancy (not a melenoma)
