Diseases of the skin and eye Flashcards by Grace Hopkinson

Give 2 infections which cause inflammation of cornea and conjunctiva?

1) Herpes varicella zoster virus - if trigeminal nerve involved can cause blindness
2) Chalmydia

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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

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Give the 6 causes of cataracts?

1) Senile degeneration
2) Rubella
3) Down’s syndrome
4) Irradiation
5) Diabetes
6) Uveitis

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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

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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

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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

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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

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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.

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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

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Which 2 tumours can arise within the eye?

1) Retinoblastoma

2) Melanoma - arises from melanocytes of uveal tract

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What is the genetics of retinoblastoma?

10% familial, due to deletion of long arm of chromosome 13 - loss of RB gene

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How is retinoblastoma treated? 2

1) Enucleation

2) DXT

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Where does a melanoma of the eye arise from?

From the melanocytes of the uveal tract - iris, ciliary body, choroid

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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

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How is a uveal melanoma treated? 2

1) Radiotherapy and surgery

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Which types of herpes simplex virus causes coldsores and which is an STD?

HSV 1 - coldsores

HSV 2 - STD, causes genital warts

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Leprosy is caused by what microorganism?

Mycobacterium leprae

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Leprosy is what kind of infection?

Chronic granulomatous infection which can involve nerves leading to loss of sensation

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Fish tank granuloma is caused by direct inoculation by what mycobacterium?

Mycobacterium marinum

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Which 2 mycobacteria can cause skin infections?

1) Mycobacterium marinum

2) Mycobacterium leprae

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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

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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)

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Atopic eczema tends to present when?

In childhood

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Atopic eczema is often associated with what 2 other conditions?

Hayfever and asthma

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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