Skin pathology Flashcards
Virilisation
female facial hair due to excess androgen from a tumour
Alopecia areata
autoimmune hair loss
Merkel cell cancer
Rare. Caused by the merkel cell virus, No vaccine and high mortality
Blister
connection between epidermis and dermis is loose, so water flows in giving a blister
Intra-epidermal blistering
presents as moist skin (exudative fluid) as blisters within the prickle cell layer burst
Warts
HPV infects keratinocytes which leads to a stimulation of hyperkeratisation giving raised warts
Loss of filaggrin predisposes to…
eczema
What is the most common form of skin cancer?
Basal cell carcinoma
Where do Basal cell carcinomas originate from?
hair follicle cells
What are inherited diseases of the DEJ? Give some examples
Skin fragility conditions due to a mutation in one of the proteins in the DEJ
Epidermolysis bullosa simplex (EBS) or dystrophic (EBD)
What are acquired diseases of the DEJ? Give some examples
Auto-antibodies to proteins in the DEJ
Dermatitis herpetiformis, pemphigoid
What is photoaging?
Long term sun exposure –> loss of elastin and collagen –> loss of skin texture –> wrinkles
What is a port wine stain?
Angioma = fixed dilation of blood vessels in the skin
What is allergic contact dermatitis?
Inflammatory reaction (dermatitis) with pruritic erythema, oedema and often vesicles at the site of chemical contact
When does allergic contact dermatitis occur?
after many repeated sub-threshold exposures that do not initially induce signs of systems (afferent stage)
Gradually the patient develops the efferent/elicitation stage and symptoms occur
What is the standard diagnostic test for alergic contact dermatitis?
patch test
What triggers psoriasis?
triggered by environmental factors in genetically susceptible individuals
Describe a typical psoriatic plaque.
itchy, well defined circular-to-oval bright red/pink elevated lesions (plaques) with overlying white or silvery scale
distributed symmetrically over extensor body surfaces and the scalp
In psoriasis, activated T cells are attracted to the dermis by chemokines and secrete IL -17A/17F/22. What does this stimulate?
Keratinocyte proliferation, AMP release and neutrophil-attracting chemokines
What is icthyosis vulgaris?
Common dry skin
What is the earliest sign of tuberose sclerosis?
ash-leaf macule
How is tuberose sclerosis inherited?
autosomal dominant
new mutations are common
What tumours can manifest with tuberose sclerosis?
perungual fibroma (nail)
facial angiofibromas
Hamartomas
Bone cysts
How can epidermolysis bullosa be inherited?
dominant, recessive, new mutation or acquired
What is the difference between the 3 forms of EB?
EB Simplex - more superficial blistering
EB Junctional - split in lamina lucida, most severe form
EB Dystrophic - deeper blistering
What is the most common genetic condition associated with cafe au lait macules?
Neurofibromatosis type 1
What else can neurofibromatosis type 1 present with?
neurofibromas plexiform neuroma axillary or inguinal freckling optic glioma distinctive bony lesion 2 + Lisch molecules
What are the classifications of psoriasis in terms of body involvement?
Mild - 10% affected
A bacterial infection on top of eczema/dermatitis would be suggested by what?
crusting, weeping, pustulation and/or surrounding cellulitis with erythema of otherwise normal looking skin
sudden worsening of the condition
Give 5 points about eczema herpeticum?
Areas of rapidly worsening eczema clustered blisters consistent with early stage cold-sores "monomorphic punched out lesions" possible fever, lethargy or distress admit urgently!
Candida intertrigo.
Candida of the skin folds
Define leg ulcer.
Any break in the skin of the lower leg above the ankle that has been present for more than 4 weeks.
What questions need to be asked with regards to a leg ulcer?
Duartion of ulcer Had previous ulcer? Pain? Disturbing sleep? Affecting mobility? PMH - DVT, varicose veins, PVD, arterial disease, DM Position of ulcer meausre surface area can take photograph
Where do venous ulcers tend to develop?
around the medial or lateral malleoli
Are venous ulcers deep or superficial?
Superficial
tend to have a shallow edge
What are venous ulcers charaterised by?
lipodermatosclerosis (chronic skin cahnge with chronic venous insufficiency)
hyperpigmentation
What investigations are required for a leg ulcer?
ABPI Wound swabs - if look infected/ smelly Bloods Patch testing Duplex scan if indicated
What kind of dressing is required for a venous ulcer?
non-adherent 4 layer compression bandaging system
With compression bandaging, what length of time is aimed for the ulcer to be healed by?
12 weeks
What ABPI is normal and what indicates disease?
1.5 = calcification
What is the typical description of an arterial ulcer?
sharp, cliff-like edges
“punched out”
typically painful and deep
Where do arterial ulcers tend to appear on the body?
foot or mid-shin
Where do pressure ulcers present?
Sacrum, heels, ischea and greater trochanters
With ulcers around the ankle, what should be done to help maintain joint mobility?
ankle exercises
Where are melanocytes derived from?
neural crest
What is the correct term for freckles?
Ephilides
What are ephilides?
Patchy increase in melanin pigmentation but notumber of melanocytes
occur after UV exposure and fade again
What are actinic lentigines/ solar lentigines/ liver spots?
macules created after UV exposure but increased number of basal melanocytes so do not fade after UV exposure
usually darker and larger than ephilides
How do melanocytic naevi form?
Due to melanocytes whihc have failed to mature or igrate in-utero
Are all melanocytic naevi congenital?
No can be acquired
Congenital melanocytic naevi tend to be larger and slightly raised
How many simple melanocytic naevi do people tend to have?
20-30
How do melanocytic naevi present?
moles, macules, papules, plaques, nodules
If a person had a giant (>20cm) congenital naevus, what is the risk of melanoma?
10-15%
What are the 3 kinds of naevi?
Junctional naevus
compound naevus
Intradermal naevus
What does a dysplastic naevi look like?
> 6mm in diameter
variegated pigment
border asymmetry
relative risk of malanoma increased with number of melanocytic naevi
How is familial dysplastic naevi inherited?
autosomal inheritance
What is a halo naevus?
peripheral halo of depigmentation (AI reaction) around a naevus showing inflammatory regression
What is a blue naevus?
Entirely dermal and consist of pigment rich dendritic spindle cells
Often on backs of hands and wrists
Give some info on a Spitz naevus?
very rare
usually occur <20 years old
consist of large sindle and/or epitheloid cells
most are entirely benign but may mimic MM closely
very pink as many stromal blood cells
What are seborrheic keratoses?
benign proliferation of epidermal keratinocytes
What do seborrheic keratoses look like?
brown/blak greasy “warty” lesion with stuck on appearance but may be flat with regular border
often on trunk and face
How can seborrheic keratoses be treated?
reassurance
cryotherapy
curettage
shave excision
What is a dermatofibroma?
deep (dermal) brown/grey firm nodule
possibly due to insect bites
What is a subcorneal haemartoma and how does it present?
“talon noir” or black heel
large indurated discoid black patch
caused by trauma
Give some drugs that can cause an allergic dermatitis type reaction after exposure in the sun?
Trimethoprim Tetracyclines NSAIDs Diuretics Vit A derivatives Anti-fungals
