Diseases of the skin and eye Flashcards
Give 2 infections which cause inflammation of cornea and conjunctiva?
1) Herpes varicella zoster virus - if trigeminal nerve involved can cause blindness
2) Chalmydia
What are the 2 forms of chlamydia which can lead to inflammation of the cornea and chlamydia and how do they differ?
1) Trochoma - tropical disease which infects the cornea and conjunctiva, common cause of blindness
2) Mild disease due to chlamydia types d-k, acquired during birth from infection in the genital tract
Give the 6 causes of cataracts?
1) Senile degeneration
2) Rubella
3) Down’s syndrome
4) Irradiation
5) Diabetes
6) Uveitis
Give 2 microorganisms which can cause retinal infections, how is each transmitted ?
1) Toxoplasma - cat is host and oocyte in faeces
2) Toxocara canis - from infected dog faeces, larva migrate to retina and die causing local inflammation
What are the 2 kinds of retinal infection caused by toxoplasma, how does the prognosis of each differ?
1) Congenital infection which causes severe bilateral disease
2) Acquired causes focal inflammatory disease
Give the 3 types of retinal vascular disease?
1) Ischaemia - for various reasons leading to ischemic damage to retina
2) Hypertensive retinopathy - flame shaped haemorrhages and exudates
3) Diabetic retinopathy - dot and blot haemorrhages and exudates
What are the 2 types of macular degeneration, which is more common?
1) Dry macular degeneration
2) Wet macular degeneration
Dry macular degeneration more common accounting for 90% of cases
What is the cause of dry macular degeneration, can it be treated?
Age related - affects people of 60, have progressive visual impairment. No treatment is available.
What is the cause of wet macular degeneration, can it be treated?
Due to new vessel growth beneath the retina, can be treated with drugs and lasers, drugs inhibit vessel growth and are injected straight into eye
Which 2 tumours can arise within the eye?
1) Retinoblastoma
2) Melanoma - arises from melanocytes of uveal tract
What is the genetics of retinoblastoma?
10% familial, due to deletion of long arm of chromosome 13 - loss of RB gene
How is retinoblastoma treated? 2
1) Enucleation
2) DXT
Where does a melanoma of the eye arise from?
From the melanocytes of the uveal tract - iris, ciliary body, choroid
What are the 2 types of uveal melanoma, how do the prognoses differ?
Based on genetic profiling
Type 1: Good prognosis
Type 2: poor prognosis
How is a uveal melanoma treated? 2
1) Radiotherapy and surgery
Which types of herpes simplex virus causes coldsores and which is an STD?
HSV 1 - coldsores
HSV 2 - STD, causes genital warts
Leprosy is caused by what microorganism?
Mycobacterium leprae
Leprosy is what kind of infection?
Chronic granulomatous infection which can involve nerves leading to loss of sensation
Fish tank granuloma is caused by direct inoculation by what mycobacterium?
Mycobacterium marinum
Which 2 mycobacteria can cause skin infections?
1) Mycobacterium marinum
2) Mycobacterium leprae
What are the 3 clinical stages of eczema (dermatitis), how does each differ?
1) Acute dermatitis - skin red, some exudate, some vesicles
2) Subacute dermatitis - skin is red, less exudate, more itching and crusting
3) Chronic dermatitis - skin is thick and leathery secondary to scratching
What 3 changes do you see on microscopy in eczema?
1) Spongiosis - intercellular oedema within epidermis
2) Chronic inflammation - predominantly superficial dermis
3) Epidermal hyperplasia and hyperkeratosis (worse in chronic)
Atopic eczema tends to present when?
In childhood
Atopic eczema is often associated with what 2 other conditions?
Hayfever and asthma
What is atopic eczema caused by?
A type 1 hypersensitivity reaction to allergen
What are the 2 types of contact dermatitis, how do they differ?
1) Contract irritant dermatitis - direct injury to skin by irritant eg. acid alkali etc.
2) Contact allergic dermatitis - substance acts as haptens which combine with epidermal protein to become immunogenic
What are the 2 types of dermatitis of unknown aetiology?
1) Seborrhoeic dermatitis - affects areas rich in sebaceous glands: scalp, forehead, upper chest
2) Nummular dermatitis - coin shaped lesions
What is psoriasis?
Well define, red oval plaques on extensor surfaces (knees, elbows, sacrum) get a fine silvery scale, remove of scale results in bleeding points
Auspitz sign is related to what skin condition?
Psoriasis
What 2 other conditions/ signs are related to psoriasis?
Sero-negative arthritis
Pitting nails
What is the pathogenic mechanism behind psoriasis?
Massive cell turnover
Which genetic factor has been implicated in psoriasis?
Multiple loci (PSORS) in region of major histocompatibility complex on Chr6p2 implicated - same area involved in other autoimmune disorders
What are the 4 possible environmental triggers for psoriasis?
1) Infection
2) Stress
3) Trauma
4) Drugs
Psoriasis confers increased risk of what cancer?
Non-melanoma skin cancer
What are the 3 co-morbidities associated with psoriasis?
1) Arthropathy
2) Psychosocial effects
3) CV disease
What is the difference between discoid LE and systemic LE?
Discoid LE = skin only
Systemic LE = visceral disaease +/- skin disease
How does discoid LE appear clinically?
Red scaly patches on sun exposed skin sometimes with scarring, scalp involvement can also lead to alopecia
What is the appearance of the skin involvement in SLE?
Butterfly rash on cheeks and nose
What is lupus erythematosus?
Autoimmune disease primarily affecting connective tissues of the body - auto Ab directed at various tissues, may affect any part of the body but importantly kidneys
How can immunofluorescence be used to detect LE?
In lupus IgG is deposited in the basement membrane, using immunofluorescence - can identify that Ab to Ag on the basement membrane using a fluorescently labelled anti human Ab AbA
What kind of rash occurs in dermatomyositis?
Heliotropic rash - peri-ocular oedema and erythema, erythema in photosensitive distribution
What is the muscle component of dermatomyositis, how it be detected?
Proximal muscle weakness - check for creatinine kinase
In adults what is dermatomyositis sometimes associated with?
Underlying visceral cancer
What are bullous diseases?
Diseases involving the formation of fluid filled blisters
What is pemphigus?
Group of disorders characterised by loss of cohesion between keratinocytes resulting in an intraepidermal blister - these blisters can rupture easily and can be extensive, involving mucous membranes
What is the pathogenesis of pemphigus?
Autoantibodies, directed against intercellular material can be detected by immunofluorescence
What is bullous pemphigoid?
Disease characterised by subepidermal blisters - elderly with large tense bullae which do not rupture easily, can be localised or extensive
What is the pathogenesis of bullous pemphigoid?
AutoAb to glycoprotein in basement membrane- can be detected by immunofluorescence
What is dermatitis herpatiformis?
Small intensely itch blistors on extensor surfaces often in young patients
What condition is dermatitis herpatiformis associated with?
Coeliac disease
What is the pathogenesis of dermatitis herpatiformis?
IgA deposition in dermal papillae
What kind of skin condition is associated with internal malignancy?
Acanthosis nigricans (dark warty lesions in armpits)
What kind of skin lesions occur in diabetes mellitus?
Necrobiosis lipoidica (red and yellow plaques on legs)
Which skin condition is associated with infections elsewhere, particularly in the lungs?
Erythema nodosum (red, tender nodules on shins)
Porphyria leads to what kind of skin conditions, why?
Blisters and scarring of the skin - build up of porphyrin compounds in the skin, these cause tissue damage when exposed to sunlight
How can porphyria be diagnosed?
Look for porphyrins in the urine
What is the commonest type of malignant tumour of the skin?
Basal cell carcinoma
Do BCC metastasise?
Very rarely
What are the 3 main risk factors for basal cell carcinoma?
1) Sun exposure and pale skin that burns easily
2) Occasionally secondary to radiotherapy
3) Immunosuppression
Which rare syndrome is related to BCC?
Gorlin’s syndrome
What are the 6 main risk factors for Squamous cell carcinoma in the skin?
1) UV radiation
2) Radiotherapy
3) Hydrocarbon exposure
4) Chronic scars/ ulcers
5) Immunosuppression
6) Drugs - some newer drugs for melanoma
What paercentage of SCCs in skin metastasise?
5% - lip, ear, perineum
Name a premalignant disease which can preceed SCC of skin?
Actinic (solar) keratosis - dysplasia to squamous epithelium, only rarely progresses to invasive disease
What is the embryological origin of melanocytes?
Derived from neural crest
What is a benign tumour of melanocytes called?
Naevi - moles!
What is dysplastic naevus syndrome?
Families with increased incidence of melanoma with multiple clinically atypical moles
What are the 2 main types of naevi (moles)?
1) Supericial - congenital or acquired
2) Deep - blue naevi
What 4 changes to naevi may indicate malignant change to melanoma?
1) Assymetry
2) Borders uneven
3) Colour variation
4) Diameter >6mm
What are the 4 main risk factors for development of melanoma?
1) Sun exposure
2) Race - celtic, red hair, blue eyes
3) Family history - dysplastic naevus syndrome
4) Giant congenital naevi - small risk
What is lentigo maligna?
A slow growing flat pigmented patch which occurs on the faces of elderly people due to proliferation of atypical melanocytes along basal layer of epidermis, with marked sun damage
Is lentigo maligna a malignant condition with potential to metastasize?
Later in disease the melanocytes may invade the dermis (lentigo maligna melanoma) with potential to metastasize
On what part of the body does acral lentigenous melanoma form and which group is it most common in?
Palms and soles, most common in afro-carribbeans
What is the commonest type of melanoma in Britain?
Superficial spreading melanoma
How does a superficial spreading melanoma appear macroscopically?
Early on its a flat macule, later becomes a large blue/black nodule
What are the genetics of a superficial spreading melanoma?
Often BRAF mutations
By what method do atypical melanocytes in superficial spreading melanoma spread into dermis?
Pagetoid spread
How does a nodular melanoma appear and what is the prognosis?
Starts as a pigmented nodule, with or without ulceration - poor prognosis
What is the Breslow thickness and how is it used in prognosis in melanoma?
Its the measure on a microscope from granular layer of the epidermis to base of tumour - ie measure of depth of invasion of melanoma. Greater the Breslow thickeness the poorer the prognosis
Which 4 sights show poorer prognosis for melanoma (BANS)?
1) Back
2) Arms
3) Neck
4) Scalp
In additions to the BANS sights what else is an indicator or poorer prognosis?
Positive sentinel lymph node
What are the 2 treatments for melanoma?
Surgery - excise primary and lymph nodes if sentinel node positive
BRAF inhibitors - 60% of melanomas have mutation in B-raf gene
60% of melanomas carry what mutation?
BRAF mutation
