Theme 10: Skin and musculoskeletal pathology: L1 Flashcards
What is eczema/dermatitis?
- very common pattern of skin disease
- varies from trivial to severe
What are the 3 stages of eczema and what does the skin look like in each?
- Acute dermatitis - skin is red, blistering and itchy - serous exudate
- Subacute dermatitis - skin is red, less exudate, more itching, crusting
- Chronic dermatitis
- skin becomes thickened with a dense keratin layer
What is spongiosis?
- presence of an irritant/ hypersensitivity process
- there is oedema between cells causing a spongy appearance
- inflammatory cells are also seen
- characteristic of eczematous dermatitis
What are the features of atopic eczema?
- usually starts in childhood, occasionally adults
- often family history
- often associated with asthma and hay fever
What type of hypersensitivity is atopic eczema?
type 1 hypersensitivity - reaction to allergen
IgE mediated
What is contact irritant dermatitis?
direct injury to skin by irritant e.g acid, alkali
What is contact allergic dermatitis?
nickles, rubbers, dyes
delayed type IV hypersensitivity reaction
What are the two morphological subtypes of dermatitis?
- seborrheic dermatitis - affect areas rich in sebaceous glands e.g scalp, forehead, upper chest
- nummular dermatitis - coin shaped lesions
What is psoriasis?
- 1-2% population
- well defined, red oval plaques on extensor surfaces (knees, elbows, sacrum)
- fine silvery scale
- +/- pitting nails
- +/- sero-negative arthritis
What is the cellular process of psoriasis?
- psoriasiform hyperplasia
- massive cell turnover
What is the aetiology of psoriasis?
- genetic factors
- environmental triggers - infection, stress, trauma, drugs
What are the associated co morbidities of psoriasis?
- arthropathy (any disease of joints)
- psychosocial effects
- cardiovascular disease
- increased risk fo non-melanoma skin cancer
What is lichenoid pattern characterised by?
epidermal basal cell damage
What is lichen planus and where is oit found?
- inflammatory skin condition usually in adults
- on flexor surfaces, mucous membranes and genitals
- usually self limiting
- associated with viral hepatitis, HIV, drugs
What is lupus erythematosus?
- autoimmune disorder primarily affecting connective tissues of the body
- autoantibodies direct at various tissues
- renal involvement is major predictor of outcome
What are the two types of LE?
- Discoid LE (DLE) - affects skin only
2. Systemic LE (SLE) - visceral disease
What is the characterstic rash of SLE?
Butterfly rash on cheeks and nose
What is dermatomyositis?
- peri-ocular oedema and erythema (heliotropic rash)
- erythema in photosensitive distribution
What is characteristic of bullous disease?
formation of fluid filled blisters
What is the difference between a pemphigus and pemphigoid blister?
Position of blister:
- Pemphigus is inter-epidermal
- Pemphigoid is sub-epidermal
What is pemphigus?
Groups of disorders characterised by loss of cohesion between keratinocytes resulting in an intraepidermal blister
Pemphigus and pemphigoid is caused by autoantibodies. What can detect these?
immunofluorescence
What is the difference between pemphigous and pemphigoid blisters?
Pemphigous are inter-epidermal and rupture
-pemphigoid are sub epidermal and do not rupture easily
What is dermatitis herpetiformis?
- small intensely itchy blisters on extensor surfaces
- often young patients
- associated with coeliac disease
What is acanthosis nigricans and what is it associated with?
- dark warty lesions in armpits
- associated with internal malignancy
What is pretibial myxema (dermopathy around tibia) associated with?
graves disease
What is the commonest malignant tumour?
basal cell carcinoma
What are the risk factors for BCC?
- sun exposed site, especially face
- occasionally secondary to radiotherapy
- pale skin that burns easily
- immunosuppression
- Gorlin’s syndrome (rare)
What are the early and late clinical signs of a BCC?
early: nodule
late: (rodent) ulcer
What cells do SCC arise from?
keratinocytes
What is marjolins ulcer?
SCC arises within chronic scars/ ulcers
What is the clinical appearance of a SCC?
Nodule with ulcerated, crusted surface
What is actinic keratosis?
- pre malignant disease to SCC
- dysplasia to squamous epithelium
- scaly lesion with erthematosus base
What is the function of melanocytes?
function is to form melanin which is transferred to epidermal cells to protect the nucleus from UV radiation
What is a benign tumour of melanocytes called?
naevi (moles)
What is a malignant tumour of melanocytes called?
melanoma
What are the two types of naevi?
- Superficial
2. Deep - blue naevi (mongolion spot)
Which is the most rare, yet most dangerous skin cancer?
melanoma
What are the differences in features of a naevus and a melanoma?
Naevus: Symmetrical Borders even Colour uniform Diameter < 6mm
Melanoma: Asymmetrical Borders uneven Color variation Diameter > 6mm
What is nodular melanoma?
starts as pigmented nodule +/- ulceration - poor prognosis
What is lentigo maligna?
- slow growing, flat, pigmented patch
- face-elderly people
What is acral lentigenous melanoma?
- palms and soles
- occasionally subungual
What are the prognostic factors for a melanoma?
- Breslow thickness: measure on microscope from granular layer of epidermis to base of tumour
- Site - BANS - back, arms, neck, scalp all poorer prognosis
- Ulceration
- Satellites
- Sentinel node
