W9 - Skin pathology Flashcards
Describe what H&E staining stands for?
hematoxylin and eosin stain
What does each component of H&E stain and what colour does each give?
Haematoxylin => nuclei => BLUE
Eosin => cytoplasm => PINK
Describe the layers (3) of the skin
- Epidermis
BM
- Dermis
- Subcutaneous fat
Describe the layers (5) of the epidermis
- Stratum basale (deepest)
- stratum spinosum (thickest)
- Stratum granulosum
- Stratum lucidum
- Stratum corneum (outermost)
What type of epithelia is the epidermis?
Squamous cell epithelia - highly keratinised!
Which layer of the epidermis stains more blue on H&E - basale or corneum?
Basale - because the cells are stem cells, which are rapidly dividing and have more nuclei than the superficial cells
What does the spinosum in the stratum spinosum signifiy?
The cells here have spines that connect the keratinocytes together, forming intercellular bridges.
Which is the thickest layer of the epidermis?
Stratum spinosum, also known as the squamous cell layer
How long does it take cells to reach the stratum corneum from the stratum basale?
roughly 28 days
Where are the melanocytes usually seen?
within the stratum basale
Name 5 structures seen within the dermis layer
- Sweat glands
- Sebacous glands
- Hair follicles
- Blood vessels
- Nerve endings
Inflammatory skin reactions have been divided into 3 groups based on their patterns - name them.
Epidermis
Dermis
Subcutis
Name the 4 morphological patterns of inflammatory reactions affecting the EPIDERMIS
- Spongiotic
- Lichenoid
- Psorasiform
- Vesicuobullous
Name the most common examples (2) of spongiotic reactions
Eczema, dermatitis
Histological features (4) of spongiotic reactions?
- Spongiosis (intraepidermal oedema)
- Exocytosis of lymphocytes (T cells) into the epidermis
- Superficial perivascular lymphocytic infiltration (dermis)
- Vesicles containing APCs such as Langerhan cells and T cells
Name the most common example of lichenoid inflammation
Lichen planus
What sort of disease is lichen planus?
Autoimmune disorder causing raised purple-red flat blotches on your skin, white patches in your mouth and bald patches on your scalp
Histological features (5) of lichenoid inflammation
- Irregularly thickened epidermis
- Degenerative skin cells
- Liquefaction degeneration of basal layer of epidermis
- Band of lymphocytes at the epidermal/dermal border
- Melanin pigments beneath the epidermis
What are the typical skin lesions in psoriasis?
Red patches/plaques with silvery top, usually well-deamrcated and on extensor surfaces (knees, elbows)
Does the skin cycle change in psoriasis?
Yes - from 28 days to go through the layers and shed off, in psoriasis we have fast proliferation ( sometimes even a 7 day turnover)
Describe the most common cause of psoriasiform reaction?
Psoriasis
Histological features (3) of psoriasiform reactions
- Acanthosis = thickening of epidermal layer
*due to rapid turnover and accumulation fo thick scale over site of irritation
- Parakeratosis = abnormal retention of nuclei in the stratum corneum as the keratinocytes dont have time to lose their nuclei in rapid turnover
- Hypogranulosis = little to no granular layer
Name the common causes of vesiculobullous reactions
- Pemphigoid
- Pemphigus
What is usually the underlying pathophysiology leading to vesiculobullous disorders?
Autoimmune - antibodies attacking the epidermis
Describe histological (3) and immunofluorescence (1) features of bullous pemphigoid
Histological:
- Epidermal BM destroyed by autoantibodies
- Eosinophl infiltrated
- Blisters just BENEATH the epidermis
Immunofluorescence:
- Linear IgG along the BM
What are the 2 types of pemphigus?
Pemphigus foliaceus - SUPERFICIAL
Pemphigus Vulgaris - DEEP
Describe histological (2) and IF (1) features of pemphigus vulgaris
Histological:
- Acantholysis = loss of coherence between epidermal cells due to the breakdown of intercellular bridges
- Deep intraepidermal/suprabasal blisters
IF:
- Chicken wire pattern = Intercellular deposits of IgG
Describe what the abs attack in Bullous pemphigoid and pemphigus vulgaris
Bullous Pemphigoid = BM
Pemphigus Vulgaris = Intercellular bridges
What is seborrheic keratosis?
common noncancerous growths
usually pigmented
well defined borders
stuck on appearance
Histoloigcal features (2) of seborrheic keratosis
- Acanthosis
- Horn pseudocysts
Most common form of skin cancer is
Basal Cell Carcinoma
Rodent ulcer refers to
BCC
BCC - comment on: aggressive/slow growing, metastasis, any associated mutations
- Locally aggressive
- Hardly ever metastasise
- PTCH mutation - especially implicated in Gorlin’s syndrome (predisposes young individuals to BCCs)
What does a BCC lesion look like?
Red, pearly lesion, telangiectatic blood vessels. If ulcerated = rodent ulcer.
What is actinic keratosis?
Precancerous lesion on chronically sune exposed skin, which can transform to SCC
BCC - histological features (4)
- basaloid (arising from the basal layer) epithelial tumour arising from the epidermis
- clefting = white artefact around each tumour nodule
- Mitotic activity
- Peripheral palisading = basophilic, large nuclated cells that appear to form a basal layer by forming an orderly line around the periphery of tumor nests in the dermis
Histological features (3) of actinic keratosis
- Atypia of epidermis-basal => dysplasic cells near in basal layer near BM due to high proliferation
- BM is NOT LOST
- Parakeratosis = nucleic keratinocytes in stratum corneum
What is Bowen’s disease?
What are its histological features (3)
Bowen’s disease = SCC in situ
- Full thickness atypia
- BM intact
- Increased mitotic activity
Squamous cell carcinoma - what does it normally appear like?
An irregular, keratinous nodule or a firm erythematous plaque
- frequently ulcerates
Describe histological features (5) of SCC
- Irregular agrgegates of PINK cells, tumour often PINK
- Infiltrate the dermis
- Increased mitotic activity
- Keratin pearls
- Perineural invasion
Histological features (3) of benign neivi
- Well organised neivi
- Melanocytes are small
- As we move down into dermis, melanocytes become small and have LESS mitotic activity
Malignant melanoma - histological features (4)
- Cellular atypia = melanocytes much bigger, angry looking
- Assymetry
- Pagetoid spread = melanocytes left the nest and are moving UPWARDS
- Uniform tissue - all melanocytes look the same
2 main prognostic indicators for melanoma
- Breslow thickness - MOST important (histological thickness)
- Ulceration
When do we check for BRAF V600E mutation in melanomas? and why?
BRAF mutation = in the thicker melanomas, we then check to see if the patient has a BRAF mutation because it can determine whether BRAF inhibitory therapy is useful
What do you see?
What does it signify?
Spongiotic reaction
likely eczema
What do you see?
What does it signifiy?
Lichenoid inflammation
Likely lichen planus
What do you see?
What does it signify?
Psoriasiform reaction
psoarisis
What do you see?
What does it signify?
vesiculobullous reaction
Bullous pemphigus
What does it show?
What does it signifiy?
Vesiculobullous reaction
Pemphigus vulgaris
What does this show? What does it signify?
BCC - blue tumour
What do you see? What does it signifiy?
Actinic keratosis (solar keratosis)
What do you see? What does it signify?
Bowen’s disease (SCC in situ)
What do you see? What does it signifiy?
SCC
What do you see? What does it signifiy?
SCC
What do you see? what does it signifiy?
Benign neivi
- well organised
- small melanocytes
- As they go down into the dermis, they are smaller and you don’t get mitotic activity in the dermis
What do you see? What does it signify?
melanoma
What do you see? What does it signify?
Uniform sheet of malignant melanocytes (all big + active) => melanoma
