Histopathology 11 - Dermatopathology Flashcards
What’s happening here
this is skin of old pt. Epidermis is thinner, theres also less collagen in dermis. Hence their skin is a bit thinner when you feel them on the wards
Give an example of vesiculobullous inflammation?
Bullous pemphigoid- epidermis splitting from the BM. (see pic) Most common. cystic lesions on flexor surfaces eg elbow. Normally seen in the elderly
pemphigus vulgaris - bottom of epidermis splitting
pemphigus foliaceous - top layers of the epidermis splitting
pathophysiology of pemphigoid
IgG and C3 attack the basement membrane and destroy the adhesion molecules
How can you confirm the diagnosis of pemphigoid?
Immunofluorescence of fresh samples to show IgG and C3 at the dermoepidermal junction (basement membrane)
What causes pemphigus vulgaris?
Pemphigus antibody attacks proteins that holds the keratinocytes together in the stratum spinosum (a layer in the epidermis), causing “akantholysis”, which leads to formation of *suprabasilar bulla* (bullar above the basal layer of the epidermis)
In the picture below, you can see how the epiderims has been split in half. The bottom bit is still stuck to the BM but the top has come off
(Pemphigus foliaceous is the superficial form)
which condition is similar to bullous vulgaris but the splitting happens in the higher up layers of the epidermis?
pemphigoid foliaceous. Note the pic below that it is mainly the top layers of the epidermis that’s falling off
On which surfaces does psoriasis tend to present?
Extensor
On which surfaces does eczema tend to present?
Flexor (cubital fossa/ behind your knees)
What is the appearance of basal cell carcinomas?
Pearly white border
Central area of ulceration
why is it important to check for perineural invasion
because you need to be aware of it to resect it properly. If you leave perineural invasion then 2-3 years down the line it will come back.
What do pre-cancerous skin cells (Bowen’s disease) look like histologically?
- getting bigger
- Becoming pleiomorphic (cells exhibit many shapes)
- Hyperchromatic (nuclei are darker)
- Odd-looking mitotic figures (disordered growth): cells in the middle of mitosis but just looks weird
ie it is a full thickness dysplasia but localised in the epidermis and has not invaded past the BM yet.
What is the upward spread of melanocytes known as?
Pagetoid spread- this is not good and is a sign of malignant melanoma. Because melanocytes normally move down
When would mitotic figues in the skin not be alarming?
Pregnancy
The Breslow thickness is used to stage which skin cancer?
Malignant melanoma
*Distance between granular layer and bottom of the tumour*
*Number 1 prognostic indicator (staging mainly determined by Breslow thickness and ulceration)*
*If the melanoma is thick, we check for BRAF V600E mutation to see if it can be treated*
Which common skin cancer does not metastasise?
Basal cell carcinoma
Is diameter or thickness more important for malignant melanoma?
Thickness
Which patient group is most at risk of pemphigus foliaceus?
The elderly - but it’s rare
Which cells of the immune system are most involved in eczema?
T-cell mediated pathology
Eosinophils recruited to sites of inflammation
What’s going on here?
Keratin horns in the epidermis- keratinocytes producing keratin that’s trapped inside these cirles. This is characteristic of seborrheic keratosis
Which skin condition appears as a “pigmented cauliflower”?
Seborrhoeic keratosis
what is happening here
BCC
- Large islands of tumour invading to the dermis
- BCCs do NOT metastasise, they are locally invasive
- The cancer arises from the keratinocytes/ epithelial cells along the bottom of the epidermis
- These cells break through the basement membrane and go into the underlying submucosa/ dermis
- They can spread via the nerves and lymphovascular system or they can cause local infiltration
Describe the appearance of a sebaceous cyst?
Round, smooth surface, central punctum, non mobile
Sebaceous cyst is a bit of a misnomer because most of the time it is an epidermoid cyst because the epidermis is invaginated and trapped in the dermis. When entrapped they carry on producing a lot of keratin and can get infected which smells
What is the most common inflammatory reaction pattern?
Spongiotic - eczema is the most common example of spongiotic dermatitis. (this is a T cell mediated response, involving Eosinophil infiltrate)
this is when the gaps between the cells increases because there’s fluid. This makes the epidermis soggy hence the name ‘spongiosis’
what is this
benign junctional naevus
- junctional because it is a nest of melanocytes at the junction of the dermis and the epidermis
- normally there arent that many melanocytes but in this condition you get a whole group of them (nest)
what is happening here
this is a benign compound naevus. benign junctional naevus can sometimes progress into this. Compound = theres melanocytes in both dermis and epidermis. This is normal because melanocytes tend to move down as they mature so they can enter dermis
which condition is similar to bullous vulgaris but the splitting happens in the higher up layers of the epidermis?
pemphigoid foliaceous. Note the pic below that it is mainly the top layers of the epidermis that’s falling off
What’s happening here?
parakeratosis (nuclei in the stratum corneum due to rapid turnover and insufficient maturation of keratinocytes) and also loss of granular cell layer in the epidermis. These are all signs of psoriasis
what is happening here
Lichenoid reaction: (an example of this is lichen planus). A lot of lymphocytes in the dermis attacking the basement membrane (the purple layer is the lymphocytes).
Often the demarcation of BM is lost because the lymphocytes are attacking this
What is happening here
The white lines are called wickham striae which are signs of Lichen planus
what is happening here
Lichenoid reaction: (an example of this is lichen planus). A lot of lymphocytes in the dermis attacking the basement membrane (the purple layer is the lymphocytes).
Often the demarcation of BM is lost because the lymphocytes are attacking this
what is this and what does it suggest
pyoderma gangrenosum - normally associated with other systemic conditions eg IBD, SLE
