63 - Inflammatory Skin Diseases, Skin Tumours, The eye Flashcards
Herpes varicella zoster
If trigeminal nerve involed can cause scarring - inflames: cornea and conjunctiva
Chlamydia inflaming cornea and conjunctiva
Trachoma is a tropical disease which infects the corneum and conjunctiva which is a common cause of blindness
Causes of cataracts
affects lens
Senile degeneration Rubella Down's Irradiation DM Uveitis
Retinal infections
Toxoplasma
Toxocara canis
Toxoplasma
Cat is host and oocyst in faeces
Congenital infection can cause severe bilateral disease
Toxocara canis
From infected dog faeces
Larva may migrate to retina and die causing localised inflammation
Retinal vascular disease
Ischaemia - atheroma, vasculitis, embolis of retinal art. Ischaemic dmg to retina.
Hypertensive retinopathy - flame shaped haemorrhage and exudates
Diabetic retinopathy - dot and blot haemorrhages
Macular degeneration
Damage to macule - central part of vision
dry macular degen
age related 90% cases Affects >60 yo Progressive visual impairment No treatment
Wet macular degen
10% due to new vessel growth beneath retina
Treat with drugs and lasers
Drugs inhibit vessel growth injected directly into the eye
Eye tumours
RB
Melanoma
RB
Rare, 10% familial
Genetics: deletion of long arm of chromosome 13 - loss of RB gene.
Melanoma of eye
arise melanocytes of uveal tract (iris, ciliary body or choroid)
Common skin infections
Herpes varicella zoster - chickenpox, shingles
HSV 1: cold sores
HSV2: genital herpes, STD
Common bacterial skin infections
Superficial - Impetigo, staph infection usually in young children. Infection in corneal later. Clinically: crusted yellow scale with pustules
Deep - cellulitis, often strep. pyogenes. infection of dermis. Clinically: hot, red, swollen painful area. Necrotising fasciitis (flesh eating bug)
Abscesses are
deep collection of pus
mycobacteria are
fish tank granuloma, direct inoculation on hand
leprosy caused by
mycobacterium leprae
leprosy is a
chronic granulomatous infection. can involve nerves, loss of sensation
fungal infections
ring worm - tinea pedis (athlete’s foot)
tinea cruris (groins) likes hot moist areas
thrush - candida infection. warm, moist areas. vagina, nappy rash, oral.
Eczema/dermatitis
Many types. Eczema is greek for boil over.
5% of children in UK
3 stages of eczema
Acute - skin red, weeping serous exudate ± vesicles
Subacute dermatitis - skin is red, less exudate, itching ++, crusting
Chronic dermatitis - skin thick and leathery secondary to scratching
Microscopy of eczema
Spongiosis (intercellular oedema within epidermis)
Chronic inflammation - predominantly superficial dermis
Epidermal hyperplasia and hyperkeratosis
Contact irritant dermatitis
Direct injury to skin by irritant e.g. acid, alkali, strong detergent
Contact allergic dermatitis: nickel, dyes, rubber
Unknown aetiology dermatitis
Morphological subtypes - seborrhoeic dermatitis: affect areas rich in sebaceous glands: scalp, forehead, upper chest.
Nummular dermatitis - coin shaped lesions
Psoriasis
1-2% of population
Well defined red oval plaques on extensor surfaces (knees, elbows, sacrum)
Fine silvery scale. Auspitz sign. Removal of scale causes small bleeding points. ± pitting nails, ±sero–ve arthritis
Psoriasis microscopy
psoriasiform hyperplasia
Regular elongated club shaped rete ridges.
thinning of epidermis over dermal papillae.
parakeratotic (contain nuclei) scale.
Collection of neutrophils in scale (Munro microabscesses)
Psoriasis aetiology
Genetic factors
FH
PSORS loci is histocompatibility complex on chromosome 6
autoimmune disorders e.g. IBD, MS
environmental triggers
Psoriasis associated comorbidity
Arthropathy: 5-10% associated
Psychosocial effects
CVD = 2-3x risk, inflammation, drugs, stress, smoking
Cancer: increased risk of non-melanoma skin cancer, lymphoma, disease or treatment effect
Lupus erythematous
Discoid LE - skin only
SLE - visceral disease ± skin
LE - clinical presentation
Red scaly patches on sun-exposed skin ± scarring, scalp involvement, causes alopecia
SLE - clinical presentation on skin
butterfly rash on cheeks and nose
LE - what is it?
auto-immune disorder primarily affecting connective tissues of the body.
Autoantibodies directed at various tissues
LE - microscopically
Thin atrophic epidermis. Inflammation and destruction of adnexal structures.
IMF-LE band. IgG deposited in basement membrane
LE - diagnosis
Immunofluorescence
Dermatomyositis - clinical presentation
Peri-ocular oedema and erythema (Heliotropic rash)
Erythema in photosensitive distribution
Myositis: proximal muscle weakness. Can check for creatinine kinase
25% associated with underlying visceral cancer
Dermatomyositis - microscopy
Similar to LE
Often a lot of dermal mucin
Negative IMF
pemphigus vs pemphigoid
intra-epidermal bulla + IMF-intercellular = pemphigus
sub-epidermal bulla + IMF basement membrane = pemphigoid
Pemphigus - pathophysiology
Group of disorders characterised by loss of cohesion between keratinocytes resulting in an intraepidermal blister
Autoantibodies vs intercellular material
Pemphigus - clinical presentation
All types cause fragile blisters/bullae which rupture easily. Can be extensive ± mucous membranes
Pemphigus - tests
IMF - immunofluorescence
Bullous pemphigoid -
subepidermal blisters
Bullous pemphigoid -clinical presentation
elderly with large tense bullae which do not rupture easily
localised or extensive
Bullous pemphigoid - pathogenesis
autoantibodies to glycoprotein in basement membrane.
detected by IMF
Dermatitis herpetiformis - clinical presentation
small intensely itchy blisters on extensor surface - sub-epidermal bulla
Bullous pemphigoid - who?
young, associated w/ coeliac
Bullous pemphigoid - pathophysiology
IgA deposition in dermal papillae on IMF
Bullous pemphigoid - histopathology
neutrophil microabscesses in dermal papillae
Acanthosis nigricans
dark warty lesions in armpits linked with internal malignancy
Necrobiosis lipoidica
red + yellow plaque on legs and diabetes mellitus
Erythema nodosum
red tender nodules on shins associated with infections elsewhere esp. lung, drugs and other diseases
Xanthoma’s
yellow plaques often eyelids and hyperlipidaemias
Gout
found on tophi
Porphyria
Group of disorders caused by defective synthesis of haem, part of haemoglobin
PCT stands for
porphyria cutanea tarda
PCT - aetiology
20% inherited A.D.
80% acquired (Hep C)
-OH can precipitate
PCT - what is it?
enzyme deficiency; uroporphyrinogen decarboxylase deficiency UROD.
Leads to build up of porphyrin compounds in the skin. Cause tissue damage when exposed to sunlight.
PCT - clinical presentation
Blisters and scarring of skin
PCT - diagnosis
look for porphyrins in urine (goes dark on light exposure)
Skin tumours - tumours for each level
Epidermis: BCC, SCC Melanocytes: naevi, melanoma Merkel cell tumour: rare Adenexal structures: sweat gland, hair follice tumours and cysts Haemangioma, neuroa
Dermatofibroma = connective tissue
What is the commonest malignant tumour?
Basal cell carcinoma
Basal cell carcinoma - aetiology
sun exposed site mainly face and 2° to radiotherapy
Basal cell carcinoma - who?
pale skin
immunosuppression
Rare - Gorlin’s syndrome
BCC stands for?
Basal cell carcinoma
Basal cell carcinoma - clinical presentation
early: nodule
late: ulcer (rodent ulcer)
Morphoeic BCC is ill defined and infiltrative
Basal cell carcinoma - microscopically
tumour composed of islands of basaloid cells with peripheral palisade
SCC stands for?
Squamous cell carcinoma
SCC - cause
UV radiation Radiotherapy Hydrocarbon exposure: tars, mineral oils, soot Chronic scars/ulcers Immunosuppression Drugs
SCC - clinically
nodule with ulcerated crusted surface
SCC - microscopically
invasive islands and trabeculae of squamous cells showing cytological atypia
SCC - mets and high risk features
mets in 5% (lip, ear, perineum)
>2cm, >4mm thick
SCC - actinic keratosis
pre-malignant disease -> actinic [solar] keratosis
dysplasia to squamous epithelium
v.common on chronic sun exposed sites
SCC - actinic keratosis clinical presentation
scaly lesion with erythematous base
Melanocytes - derived from?
neural crest
Melanocytes - function
to form melanin which is transferred to epidermal cells to protect the nucleus from UV radiation
Naevi
are moles
local benign collections of melanocytes
types of naevi
superficial - congenital or acquired
deep; blue naevi = mongolion spot
Dysplastic naevus syndrome -
families with increased incidence of melanoma
multiple clinically atypical moles which are histologically atypical
Melanoma -
rarer than BCC and SCC
incidence is rising rapidly
dangerous and can met widely
naevus vs melanoma
melanomas are ABCD
asymmetrical
borders uneven
color variation
diameter >6mm
naevus is the opposite
Lentigo maligna - who?
face, elderly people
slow growing, flat pigmented patch
Lentigo maligna - microscopically
proliferation of atypical melanocytes along basal layer of epidermis
skin also shows sign of chronic sun damage
Lentigo maligna - late stage
may invade dermis with potential to met
Acral Lentigenous Melanoma -
palms and soles, occasionally subungual
Acral Lentigenous Melanoma - who?
commonest form in afro-caribbeans.
forms enlarging pigmented patch
Acral Lentigenous Melanoma - microscopically
similar to lentigo maligna except no marked sun damaged
Superficial spreading melanoma -
commonest type in britain
Superficial spreading melanoma - disease progression
early - flat macule
late - blue/black nodule
Superficial spreading melanoma - microscopic
proliferation of atypical melanocytes which invade epidermis and dermis
Superficial spreading melanoma - genetics
BRAF mutations
Nodular melanoma -
starts as pigmented nodules ± ulceration
poor prognosis
Nodular melanoma - microscopic
invasive atypical melanocytes invade dermis to produce nodules of tumours cells
Prognostic factors
Breslow thickness.
Site - BANS - back, arms (post. upper) neck, scalp.
All poorer prognosis
Senitel node - removed and, if positive, rest of lymph nodes are removed
Breslow thickness
Measure on microscope from granular layer of epidermis to base of tumours which then predicts 5 yr survival rates
Melanoma treatment
Surgery - excise primary and lymph nodes if sentinel node positive
BRAF inhibitors - 60% malanomas have mutation in B-raf gene.
