Dermatology Flashcards
What is necrotizing fasciitis?
A fulminant, rapidly spreading infection with widespread tissue destruction through all tissues and planes
What is the mortality like for necrotising fasciitis?
Very high
What is type 1 necrotizing fasciitis caused by?
aerobic and anaerobic bacteria, seen post surgery or in diabetics
What is type 2 necrotizing fasciitis caused by?
group A streptococci (GAS), arising spontaneously
What are the symptoms of necrotizing fasciitis?
severe pain at site of initial infection with tissue necrosis
spreading infection across all planes
spreading erythema, pain and crepitus
fever, toxicity and pain
What do investigations show in necrotizing fasciitis?
increased CRP, ESR, WCC
What is the treatment for necrotizing fasciitis?
antibiotics (2 = benzylpenicillin and clindamycin, 1 = broad spectrum), surgical exploration, amputation
What is cellulitis?
infection of the deep subcutaneous layer
What are the symptoms of cellulitis?
hot and tender area, blisters, low grade fever, lymphedema, poorly demarcated margins
Where about does cellulitis affect and then spread to?
Starts in the lower leg and spreads upwards
How does the skin appear in erysipelas?
larger area with erythematous and sharply demarcated from normal skin
What causes cellulitis?
beta-haemolytic streptococcus, staphylococcus or MRSA
Investigations for cellulitis?
swab of toes, antistreptolysin O titre (ASOT) and antiDNAse B titre (ADB)
What is erysipelas?
a more superficial infection of cellulitis, often of the face, has a well demarcated edge
What is the treatment of cellulitis?
phenoxymethylpenicillin and flucloxacillin (IV or oral depending on how widespread), treat underlying cause, low dose antibiotic prophylaxis if recurrent to prevent further lymphatic damage
What is vasculitis?
Inflammatory disorder of blood vessels causing endothelial damage
What are the symptoms of vasculitis?
haemorrhagic papules, pustules, nodules, plaques that can erode and ulcerate, don’t blanch from glass slide, fixed livedo reticularis pattern, pyrexia and arthralgia
What is leucocytoclastic vasculitis?
the most common cutaneous vasculitis affecting the small vessels
how does leucocytoclastic vasculitis usually appear?
on lower legs as a symmetrical palpable purpura
What is the treatment of vasculitis?
can resolve spontaneously, analgesia, support stockings, dapsone, prednisolone
What is the cause of leucocytoclastic vasculitis?
drugs, infection, inflammatory disease, malignant disease, idopathic
What causes pressure sores?
elderly, immobile, unconscious, paralysed from skin ischemia, sustained pressure over bony prominence
What are the four grades of pressure sores?
1 - non blanchable erythema of intact skin
2 - partial thickness skin loss of epidermis/dermis
3 - full thickness skin loss involving subcutaneous tissue, not fascia
4 - full thickness skin loss involving muscle, bone, tendons and joint capsule
What is the risk assessment scale called for pressure sores?
Norton scale and waterlow pressure sore risk assessment
What is the treatment for pressure sores?
bed rest, pillows, air filled cushions, pressure relieving mattress, regular turning, adequate nutrition, non irritant occlusive moist dressings, analgesics, plastic surgery, treat underling cause
What is eczema?
superficial skin inflammation with vesicles, redness, oedema, oozing, scaling and pruritis
What is the cause of eczema?
Atopy - initial selective activation of Th2 type CD4 lymphocytes in the skin which drive the inflammatory process
How common is eczema and who is most likely to have it?
In 5% of the population 10-20% of children Genetic disease More likely if atopic 20-30% chance of passing onto child
What are some exacerbating factors of eczema?
dust mites, food allergies, pets, teething, strong detergents, chemicals, woollen clothes, lack of infection in infancy
What are the clinical features of eczema?
itchy erythematous scaly patches in flexures, hyper or hypo pigmented skin, blisters if herpes infection, can be punched out lesions (eczema berpeticum)
Where does eczema commonly occur on the body?
elbow, ankles, knees, neck
How does scratching affect eczema?
produces exconations, causes skin thickening with exaggerated skin markings, can become infected
What is the treatment of eczema?
avoid irritants, emollients to hydrate the skin, topical corticosteroids, mild steroids for face (hydrocortisone) and more potent on body (betamethasone or flucinolone), topical immunomodulators (tacrolimus and pimecrolimus), antibiotics if infected, bandaging, oral prednisolone if severe
What is exogenous eczema?
Aka contact dermatitis, acute or chronic skin inflammation with sharply demarcated edges, caused by substances in contact with the skin
What are the causes of exogenous eczema?
chemical irritants e.g. industrial and cleaning solvents leads to a sensitisation of T lymphocytes over a period of time
What are the clinical features of exogenous eczema?
rash with clear cut demarcation or odd shaped areas of erythema and scaling
How can you test for exogenous eczema?
Patch testing with suspected allergen
What is the management of exogenous eczema?
remove causative agent, steroid creams for a short period of time, antipruritic for itching relief
What is acne vulgaris?
facial rash in adolescents
What causes acne vulgaris?
seborrhea (high sebum production - an androgenic hormone), comedo formation with ductal hypercornification, colonisation of the pilosebaceous duct with propionibacterium acnes and inflammation of the pilosenaceous unit
follicular epidermal hyper proliferation, blockage of pilosebaceous units with surrounding inflammation , increased sebum production and infection with Propionibacterium acnes via activation of Toll like receptor 2, leading to inflammatory cytokine production
What are the symptoms of acne vulgaris?
open (black) or closed (white) comedones, inflammatory papules, pustules, greasy skin (seborrhoea), rupture of inflamed lesions lead to deep seated dermal inflammation and nodulystic lesions, facial scarring
Where does acne vulgaris commonly occur on the body?
face, back and sternal areas
What is infantile acne?
facial acne in infants and sometimes cystic
What causes infantile acne?
maternal androgen influence
What is steroid acne?
Occurs secondary to corticosteroid therapy of Cushings, appearing as pustular folliculitis on trunk
What is oil acne?
Seen in industrial workers with prolonged oil contact, common on the legs
What is acne fulminars?
severe, necrotic and crusted acne lesions
Who is acne fulminars seen in?
Rare and in young male adolescents
What is the treatment of acne fulminars?
oral prednisolone, analgesics and oral isotretinoin
What are the symptoms of acne fulminars?
malaise, pyrexia, arthralgia, bone pain due to sterile bone cysts
What is acne conglobate?
cystic acne with abscesses and interconnecting sinuses
What is acne excoriee?
deeply exconated and pickled acne with scarring
Who is most like to acquire acne excoriee?
Females
What is follicular occlusion triad?
severe nodulocystic acne, dissecting cellulitis of the scalp, hidraderitis suppurativa
What is the cause of follicular occlusion triad?
Follicular occlusion
Who is most likely to have follicular occlusion triad?
Black Africans, rare
What is the 1st line treatment of acne?
topical agents e.g. keratolytics
topical retinoids e.g. tretinoin or retinoid like agents
topical antibiotics e.g. crythromycin for inflammatory acne
benzoyl peroxide and azelaic acid (antimicrobial, comedolytic and keratolytic properties)
retinoids, nicotinamide
What is the 2nd line treatment of acne?
low dose oral antibiotics for 3-4 months e.g. oxytetracycline, minocycline, erythromycin
hormonal treatment with cyproteroneacetate or ethinylestradiol
What is a side effect of 2nd line acne treatment?
DVT
What is the 3rd line treatment of acne?
oral retinoid e.g. isotretinoin
synthetic vitamin A analogue that affects cell growth and differentiation
tetratogenic
What is 3rd line acne treatment contraindicated for and what measures prevent this?
pregnancy, so must have test and contraceptive advice before
What is psoriasis?
A papulo squamous disorder with well demarcated red scaly plaques and inflamed skin - remission and relapses common
Who is most likely to get psoriasis?
male = female
common n 16-22 and 55-60years
2% of pop.
What is the cause of psoriasis?
group A streptococcus, lithium, UV light, alcohol and stress
How does psoriasis occur?
driven by T lymphocytes , resulting in upregulation of Th1-type T cell cytokines and adhesion molecules
What will a skin biopsy show of psoriasis?
epidermal ocanthosis and parakeratosis, increased skin turnover, absent granular layer, hyperproliferation, thickened epidermis
What are the clinical features of chronic plaque psoriasis?
pinkish red scaly plaques and silver scale on extensor surfaces or sites of trauma, becomes itchy and sore, is lifelong (arthritis and nail changes can accompany it)
What are the clinical features of flexural psoriasis
well demarcated, red glazed plaques confined to flexures
Where does flexural psoriasis commonly appear?
at groin, nasal cleft and sub mammary areas
How does guttate psoriasis appear on the skin?
explosive eruption of very small circular plaques over the trunk caused by streptococcal infections
When does guttate psoriasis commonly occur?
2 weeks after streptococci sore throat
In who does guttate psoriasis normally appear in?
children and young adults
How does erythrodermic and pustular psoriasis normally appear?
pustular psoriasis on hands and feet
What symptoms usually accompany erythrodermic and pustular psoriasis?
malaise, pyrexia, circulatory disturbance (systemically unwell)
What type of nail changes can occur in psoriasis?
pitting of the nail plate, distal separation of nail plate, yellow brown discolouration, sublingual hyperkeratosis, damaged nail matrix
What is the treatment of psoriasis?
topical treatment, phototherapy, systemic therapy and cytokine modulators
How does topical therapy treat psoriasis?
hydrates skin, anti proliferative, vitamin D analgues e.g. calcpotriol and calcitrol reduces cell division, coal tar, tazorotene and corticosteroids, topical dithronol inhibits DNA synthesis but can stain the skin, salicyclic acid acts as a keratolytic and helps scalp
How does phototherapy treat psoriasis?
UV A/B radiation in conjunction with a photosensitising agent, good for extensive psoriasis
What are risks of phototherapy treatment in psoriasis?
can exaggerate skin aging and increase risk of UV induced skin cancer
How does systemic therapy treat psoriasis?
oral retinoic acid derivatives e.g. acitretin or etretinate, immunosuppressives e.g. methotrexate or ciclosporin, biological agents e.g. TNF a blockers can all be used in resistant disease or severe, coal tar therapy, dithranol
What is the risk of retinoic acid derivatives in psoriasis?
They are teratogenic so CI if pregnant
What are the most common causes of skin cancer?
sun exposure, genetics and ethnicity
What is the most common type of malignant skin tumour?
basal cell carcinoma (rodent ulcer)
What is the cause of basal cell carcinoma?
excessive sun exposure and Gorlins syndrome, immunosuprresion
Why does Gorlins syndrome cause basal cell carcinoma?
mutation in the PTCH1 gene
What is the appearance of a basal cell carcinoma?
papule or nodule that can ulcerate, telangiectasia or pearly edge over the tumour, flat diffuse superficial form, ill defined morpreic variant