Pathology Flashcards
What type of epithelium is the epidermis?
Keratinised stratified squamous epithelium
Which epithelial layer contains prominent desmosomes?
Prickle cells layer
Which epithelial layer is rich in kerato-hyalin granules?
Granular layer
Which epithelial layer is a mitotic pool?
Basal cell layer
Where are melanocytes found?
Basal layer and dermo-epidermal junction
How do melanocytes look on histology?
Have a pale halo surrounding them
What is the function of menalocytes?
Transfer pigment to keratinocytes using dendritic processes
Where are Langerhan’s cells found?
Upper and mid epidermis
The dermis is made up of what?
Type 1 and 111 collagen, elastic fibres and ground substance
Which area of the dermis is thin and found just below the epidermis?
Papillary dermis
What area of the dermis makes up most of it and is made from thicker bundles of type I collagen?
Reticular dermis
Which part of the dermis contains the appendage structures?
Reticular dermis
What is the epidermal basement membrane made up of?
Laminin and collagen IV
What is hyperkeratosis?
Increased thickness of the keratin layer
What is parakeratosis?
Persistence of nuclei in the keratin layer
What is acanthosis?
Increased thickness of the epithelium
What is papillomatosis?
Irregular epithelial thickening
What is spongiosis?
Oedema fluid between cells increasing the prominence of prickles
If oedema between cells is severe, what will form?
Vesicles
What is the main spongiotic disease?
Eczema
Where is the damage in lichenoid disorders?
Basal layer (basement membrane)
Give two examples of licheniod disorders?
Lichen Planus and lupus
Vesiculo-bullous disorders are characterised by what? Give 3 examples.
Blistering: bullous pemphigoid, pemphigus vulgaris, dermatitis herpetiformis
What happens to the epidermis in psoriasis?
Increased turnover and hyperplasia
What is the Koebner phenomenon?
New lesions of psoriasis occurring at sites of trauma
In psoriasis, what mediates the attack on the keratin layer?
Complement which then attracts neutrophils
What is erythoroedema?
An acute form of psoriasis which is often caused by drugs and can affect the whole body
What will the rash look like in lichen planus?
Itchy, flat topped violet papules
Irregular saw-toothed acanthosis is associated with what condition?
Lichen planus
In lichen planus, there will be upper dermal infiltrate of what?
Lymphocytes
What are Wichen’s straie?
White stripes on the buccal mucosa seen in lichen planus
What is pemphigus?
A rare, autoimmune bullous disease normally in middle age with loss of integrity of epidermal cell adhesion
Pemphigus responds to treatment with what?
Steroids
What is the most common type of pemphigus?
Pemphigus vulgaris
Pemphigus vulgaris involves IgG antibodies against where?
Desmoglein 3 which maintains desmosomal attachments
What is the end result of pemphigus vulgaris?
Acantholysis (loss of cellular connections)
Where is the blister in bullous pemphigoid?
Subepidermal
Immunofluorescence shows what in bullous pemphigoid?
IgG and complement deposited around the basement membrane
If you send older lesions of bullous pemphigoid for histology, what can they mimic?
Pemphigus vulgaris
What bullous skin condition has a strong association with coeliac disease and HLA-DQ2?
Dermatitis herpetiformis
What will dermatitis herpetiformis cause?
Intensely itchy, symmetrical lesions
What is the hallmark of dermatitis herpetiformis?
Papillary dermal microabscesses
In dermatitis herpetiformis, there will be deposits of what in the dermal papillae?
IgA
The distribution of acne reflects what?
Sebaceous gland sites
Acne is caused by what?
Increased androgens at puberty
What causes the infection in acne?
Anaerobic bacteria- corynebacterium acnes
Where are common sites to get dermatitis herpetiformis?
Elbows, knees, buttocks
Rosacea is more common in which sex? What are some triggers?
Females: spicy food, alcohol, sunlight, stress
What happens in rosacea?
Recurrent facial flushing with visible blood vessels, pustules and thickening of the skin (rhinophyma)
Some cases of rosacea respond to what medication?
Tetracyclines
The presence of what might be noted in rosacea?
Follicular demodex mites
Most malignant melanocytic tumours are due to what?
UV light
What two types of skin tumour are exclusively epidermal?
BCC and SCC
When can skin tumours kill you?
Below the basement membrane (in the dermis)
Where can skin tumours reach once they are in the dermis?
Vessels and lymphatics which allow them to spread
Once melanocytes settle in the skin they are usually situated where?
Basally
Does the melanocyte ratio change depending on race?
No
What does the melanocortin 1 receptor gene encode? What is the function of this?
Encodes MC1R protein which sits on the cell surface and determines the balance of pigment in skin and hair
What do phaeomelanin and eumelanin cause?
Phaeomelanin- all hair colours except red
Eumelanin- red hair
What turns phaeomelanin into eumelanin?
MC1R gene
What does 1 defective copy of the MC1R gene cause?
Freckling
What do 2 defective copies of the MC1R gene cause?
Freckling and red hair
What are ephilides?
Freckles
What causes freckles?
A patchy increase in melanin pigmentation after UV exposure, in individuals who are genetically predisposed
Actinic lentigines (age spots) are related to what?
UV exposure causing increased melanin and basal melanocytes
When are most melanocytic naevi acquired?
The first 2 decades
What defines small and medium congenital naevi?
Small = < 2cm, Medium = 2-20cm
What is the risk of melanoma in large congenital naevi?
10-15%, may need surgical excision
Describe simple naevi?
Very common benign lesions with low malignant potential
Acquired naevi develop throughout life. In childhood it is known as junctional- where are the melanocytes?
In clusters at the DEJ
Acquired naevi develop throughout life. In adolescence it is known as compound- where are the melanocytes?
DEJ and dermis
Acquired naevi develop throughout life. In adulthood it is known as intra-dermal- where are the melanocytes?
Entirely dermal
Describe clinical features of dysplastic naevi?
Generally >6cm diameter, varied pigment, asymmetrical
Describe sporadic dysplastic naevi?
Not inherited, one-several atypical naevi, slight raised risk of melanoma
Familial cases of dysplastic naevi have a strong family history of melanoma. How are these inherited and what is the penetrance?
Autosomal, high penetrance
How many atypical naevi are normally seen in an individual with familial dysplastic naevi? What is the risk of melanoma?
Lots of atypical naevi, 100% lifetime risk of melanoma
On histology, dysplastic naevi can show what?
Large nuclei and signs of inflammation with possible fibrosis
Halo naevi have a peripheral halo of depigmentation. How does this occur? What are they overrun by?
Damage to the melanocytes around the lesion, overrun by lymphocytes
Blue naevi are found where in the skin? What do they consist of?
Entirely dermal, consist of pigment rich dendritic spindle cells
Who do Spitz naevi occur in?
< 20 years, often in children
Are Spitz naevi benign? What may be seen on histology?
Yes, you may see epidermal hyperplasia
Which sex is more likely to get a melanoma? When is the peak incidence?
Females (2:1)- middle age
Where are melanomas mostly seen?
On sun exposed sites
Superficial spreading melanomas are commonest where?
Trunk and limbs
Lentiginous melanomas are commonest where?
Palms, soles or mucosa
Lentigo maligna type melanomas are seen where?
Sun damaged face, neck, scalp
Where are nodular melanomas seen?
Can be anywhere but commonly trunk
All types of melanoma except nodular, grow as what first?
Macules (before they invade the dermis)
When can a melanoma metastasise?
When it is in the dermis (vertical growth phase)
What type of melanoma does not have a radical growth phase?
Nodular
What is Breslow depth?
The deepest tumour from the granular layer in mm
Describe pTis, pT1, pT2, pT3, pT4?
Tis = melanoma in site, T1 = < 1mm, T2 = 1-2mm, T3 = 2-4mm, T4 = 4+mm
Adding ‘b’ after any TNM staging implies what? What does this do to prognosis?
Ulceration- decreases prognosis
What are some adverse indicators of melanoma?
High mitotic rate, lymphovascular invasion, satellites, lymph node involvement
What is the main treatment of a melanoma?
Primary excision with clear margins (+/- lymphadenectomy)
Some aural melanomas involve what mutation? What may this be treated with?
c-Kit- imatinib
Melanomas on intermittently sun exposed skin may have what mutation?
BRAF
What is BRAF? What happens if it is mutated?
A proto-oncogene, it drives cell proliferation by up regulating MEK and ERK
What type of lesion looks ‘stuck on’ and is raised, but is completely benign?
Seborrhoeic keratosis
Give 3 examples of precancerous squamous dysplasia?
Bowen’s disease, actinic keratosis, viral lesions
What invasive malignancies are epidermal?
BCC and SCC
What is seborrhoeic keratosis?
Benign proliferation of epidermal keratinocytes
Where is seborrhoeic keratosis common?
Face and trunk
What can seborrhoeic keratosis also be known as?
Basal cell papilloma
Where does BCC occur? Who in?
Sun exposed sites in middle aged-older people
How do basal cell carcinomas grow?
Slow growing, locally destructive
Do BCCs commonly metastasise?
No, very rare
How may BCCs kill?
Getting into the brain through the eye
Superficial BCC may sometimes look like a patch of eczema, how can you tell that its not?
It will not go away with steroids
What are BCCs often surrounded by?
Telangectasic vessels
What is Bowen’s disease?
Squamous cell carcinoma in situ
Which sex is more likely to get Bowen’s disease? Where is it likely to appear?
The lower leg in females
How will Bowen’s disease look?
Scaly patch or plaque, irregular border
What two conditions can cause stasis dermatitis?
BCC and Bowen’s disease
Where does actinic keratosis appear?
Sun exposed sites, especially head and neck
All precursors of SCC show what?
Squamous dysplasi
Where are viral precursors of SCC most commonly seen?
Ano-genital skin
What is erythroplasia of Queryat-Penile?
Bowen’s disease of the penis, associated with HPV
What type of HPV is mostly associated with dysplasia of SCC?
Type 16
What is the commonest presentation of SCC?
Elderly, sun exposed skin, UV implicated, following actinic keratosis
What is the prognosis of SCC?
Good, locally invasive, low but definite risk of metastases
SCC can occasionally arise following what?
Chronic leg ulcers, burns, chronic lupus vulgaris
Xeroderma pigmentosum has a rare association with what?
SCC
What sites of SCC have a worse prognosis?
Scalp, ear or nose
Squamous cells should only be seen where?
Epidermis
What is mycosis fungoides?
Cutaneous T cell lymphoma
