Theme 10 - INFLAMMATORY SKIN PATHOLOGY Flashcards
eczma/ dermatitis is most commonly caused by what hypersensitivity reaction?
Type 1 hypersensitivity to allergen(s)
when is atopic eczema onset?
Usually starts in childhood
Often family history
Often associated with asthma and hay fever.
what are the three clinical stages of dermatitis?(eczema)
acute dermatitis (red skin, weeping exudate with small vesicles)
subacute dermatitis - skin is red, less exudate and there is more itching and crusting
Chronic dermatitis - skin is thick, leathery and there is secondary scratching
what is spongiosis?
microscopy of eczema = spongy appearance of the blistering of skin
characterised by rounding of keratinocytes and widening of intercellular spaces
formation of small intraepidermal vesicles.
what is contact irritant dermatitis?
direct injury to the skin by irritant like acid
type 4 hypersensitivity
what is contact allergic dermatitis?
WHAT HYPERSENSITIVITY REACTION IS IT?
nickel, dyes, rubber -
act as haptens that combine with epidermal protein to become immunogenic
type 4 hypersensitivity
aetiology of dermatitis
unknown
what is psoriasis presented as?
scaly patches on the extensor surfaces and hair bearing areas like the scalp
aetiology of psoriasis
GENETICS:
- family history
- susceptibility genes (PSORS)
- major histocompatability complex on chromosome 6p2
- environmental - stress, trauma, drugs and infection
associated comorbidity of psoriasis is
arthropathy
psychological effects on self esteem
cardiovascular disease
cancer
Lupus erythematosus types
Discoid LE - skin only
Systemic LE - visceral disease that involves skin
Lupus erythematosus clinical signs and symptoms
Red scaly patches on skin
Scarring
Alopecia
Butterfly rash on cheeks and nose (in SLE)
microscopy of lupus
thin atrophic epidermis
Inflammation and destruction of adnexal structures
IgG deposited in the basement membrane
dermatomyositis -
an autoimmune condition
that causes skin changes and muscle weakness.
Symptoms can include:
periocular oedema and erythema
(swelling around the eyes called a heliotropic rash)
Myositis - proximal muscle weakness
What are bullous diseases?
disorders that cause blistering of the skin
diagnosed by fluoresence in microscopy
what is pemphigus?
there is a loss of cohesion between keratinocytes that result in intra-epidermal blisters
blisters are more soft and tend to break & can involve mucous membranes
what is pemphigoid?
Sub epidermal blisters that are tough and don’t easily rupture
Intermediate filaments are detected in the basement membrane
dermatitis hepatiformis - how does it present?
intensely itchy rash
sub-epidermal blisters
IgA deposition in dermal papillae
EXAMPLES of skin lesions and them being signs of systemic disease
- Dermamyositis - sign of visceral cancer
- Dermatitis hepatiformis - coeliac disease
- Acanthosis nigricans - dark warty lesions are associated with internal malignancy
- Necrobiosis lipoidica - (red and yellow plaques on the legs) associated with diabetes
- Erythema nodosum - red tender nodules on the shins
associated with infections around the body especially lungs
How common are skin tumours?
Skin tumours are the most common type of malignancy
Which elements of the skin can tumours arise from? (6 examples)
All elements of the skin:
EPIDERMIS - basal cell carcinomas and squamous cell carcinomas
MELANOCYTES - Naevi and melanoma
MERKEL CELL TUMOUR - rare but dangerous
ADNEXAL STRUCTURES - sweat gland and hair follicle tumours and cysts
NERVES AND BLOOD VESSELS - haemangioma and neuromas
CONNECTIVE TISSUE - dermatofibromas
Basal cell carcinoma - how common is it, what is the aetiology?
Commonest malignant tumour
due to sun exposure - Usually in pale skin that burns easily e.g. of the face but can be secondary due to radiotherapy
usually disease of the elderly but Gorlin’s syndrome can cause multiple BCCs in any age
What is the clinical appearance of basal cell carcinomas?
Early stages - nodule
Late stages - ulcer (rodent ulcer)
They are often ill defined and infiltative.
what is the microscopic appearance of BCCs?
tumour is composed of islands of basaloid cells with peripheral palisade
(palisade looking like a picket fence with basaloid cells inside forming a tumour)
Do BCC metastasize?
Basal cell carcinomas do not met. but they grow in size and on the face this can reach the eye/ear/nose
Squamous cell carcinomas - where do they occur and who gets it?
UV irridiation
occurs in sun exposed sides
Can occur secondary to radiotherapy and exposure to hydrocarbons e.g. tars and mineral oils
CAN BE CHRONIC ULCERS and those who are immunocompromised are at high risk
What is the clinical appearance of SCC?
Nodule with ulcerated and crusted surface
Can metastasise e.g. in lips, ear and perineum
what is the microscopic appearance of SCC?
Invasive islands and columns of squamous cells
These cells show cytological atypia
what is Actinic keratosis?
Pre malignant disease to SCC
Caused by:
Dysplasia to squamous epithelium
what are melanocytes?
derived from neural crest embryologically
form melanin which is transferred to epidermal cells to protect nucleus from UV
What is Naevi (moles)?
local benign collections of melanocytes that can be:
Superficial: congenital or acquired
Deep: blue naevi (mongolion spot) because they have stopped the process of maturation
what is atypical mole syndrome?
Families have increased incidence of melanoma
Histologically atypical and dysplastic naevi (abnormal growth and morphology)
what are giant congenital naevi?
immatured melanocytes that appear as a large blue/black spot on an infant
Epidemiology of melanomas - How rare is it and what is the incidence like?
Much rarer than BCC and SCC
Incidence is rising rapidly
Very dangerous malignancy which can metastasize widely
What are the observational differences between Naevi and melanomas?
Naevi are:
Symmetrical
Borders are even
Uniform in colour
Have a diameter below 6mm
Melanomas: Asymmetrical Borders uneven Colour variation Diameter greater than 6mm
What are the risk factors for melanoma?
Sun exposure - short intermittent severe exposure (australia)
Race - pale skin and blue eyes are most at risk
Family history - atyptical mole syndrome are at risk
Giant congenital naevi - small risk of turning malignant
What is superficial spreading melanoma, how does it appear clinically and microscopically?
The most common type of melanoma in the UK
Early - flat macule
Late - blue/black nodule
Proliferation of atypical melanocytes which invade epidermis and dermis
BRAF mutations are…
target for anti cancer agents
What is nodular melanoma?
Pigmented (blue black) nodules with ulceration
Invasive atypical melanocytes that invade the dermis
Produce tumour cells in the dermis - poor prognosis
What is lentigo maligna?
Slow growing, flat and pigmented patches in the faces of elderly people.
Lentigo maligna microscopic appearance and clinical appearance
Proliferation of atypical melanocytes along basal layer of epidermis
Skin shows signs of chronic sun damage
What is acral lentigenous melanoma?
melanoma found on palms of hands, soles of feet and in afro-caribbean patients.
No marked sun damage
Breslow thickness
Measure on microscope from granular layer of epidermis to base of tumour.
5 year survival rates for primary melanoma
Breslow tumour
< 1 91-95
1 - 2 75-90
2 - 4.00 60-75
>4.00 45-60
Prognostic factors of skin malignancies
- Site - BANS - back, arms (posterior upper), neck, scalp.
All poorer prognosis - Ulceration
- Satellites/ in-transits [cutaneous deposits]
Sentinel Node. (Lymph node which drains from melanoma first)
Removed and if positive, rest of lymph nodes in that anatomic area removed.
What treatment options are available for skin malignancy?
Surgery –
excise primary and + lymph nodes if sentinel node positive
BRAF inhibitors-
60% melanoma’s have mutation in B-raf gene. Can use BRAF inhibitors.
Mutations conferring resistance almost inevitable
Immunotherapy –
can provide sustained remission
does not require a specific mutation
