Medicine - Dermatology Flashcards
Describe a macule
<0.5cm flat area of discolouration
Describe a patch
> 0.5cm flat area of discolouration
Describe a papule
<0.5cm palpable lesion
Describe a nodule
> 0.5cm palpable lesion
Describe a vesicle
<0.5cm fluid filled lesion
Describe a bullae
> 0.5cm fluid filled lesion
Describe a pustule
<0.5cm small pus filled vesicular lesions
Describe an abscess
> 0.5cm pus filled vesicular lesions
Describe a plaque
raised, flat topped area often with surface discharge
Describe toxic epidermal necrolysis (TEN)
A derm emergency
Drug induced blistering and skin detachment disorder
Ass. with fever and >10% body SA involved
What can cause toxic epidermal necrolysis (TEN)
Drugs! - epilepsy drugs, allopurinol, NSAIDs
How does TEN present?
- bullae
- Niklosky’s sign +ve (the epidermis sloughs easily when pressure is applied)
How is TEN managed?
- stop offending drug
- supportive
What is Stevens Johnson Syndrome?
same as TEN but <10% body SA involved
What is erythema multiforme and its S/Sx
A derm emergency
hypersensitivity reaction associated with drugs/certain infections:
- HSV
- mycoplasma pneumoniae
Has classical target appearance
Mucosal-cutaneous involvement: therefore mucosal erosions and difficulty urinating
How is erythema multiforme classified and treated?
EM minor = <10% body SA affected and no mucosal involvement
EM major = mucosal involvement
usually resolves by itself in 2-3 weeks, supportive treatment and antibiotics/antivirals depending on the cause
What is acute urticaria and its causes
A derm emergency
Itchy wheals, oedema and erythema
acute (<6 weeks)
mainly due to FOOD/DRUG allergic reactions, but also viral/bacterial infections or vaccinations
How is acute urticaria managed and what complication can arise?
Antihistamines
Steroids
Immunosuppression
Complication = anaphylactic shock!
What is erythroderma and its causes
A derm emergency
intense widespread reddening of the skin
Normally associated with other skin conditions - dermatitis, psoriasis
What are S/Sx of erythroderma
warm, itchy scaly skin
Nail thickening
serous oozing
generalised lymphadenopathy
How is erythroderma treated and what complications can arise
Emollients
Topical steroids
Antibiotics
Antihistamines
Complications: dehydration/electrolyte imbalances hypothermia hypoalbuminaemia = oedema secondary skin infections
Describe cellulitis and its RFx
Acute spreading dermal infection
RFx: PVD, DM, skin breaks, oedema, DVT, eczema
What are cellulitis S/Sx
erythema oedema warmth tenderness discomfort disruption of the cutaneous barrier
How is cellulitis investigated?
Hx and Ex Bloods Blood cultures Skin biopsy MRI (?nec fasc), X-ray (?osteomyelitis)
What classification system is used for cellulitis
Enron classification
How is cellulitis treated?
Moderate = IV flucloxacillin Severe = IV Flucloxacillin, Clindamycin, Gentamycin
Describe necrotising fasciitis and its RFx
life threatening soft tissue infection
rapidly progressive and pain out of proportion
- IVDU, immunosuppression, hospitalisation, skin lesions, VSV infection
What are the two types of nec fasc?
Type 1 - polymicrobial (in existing wounds)
Type 2 - group A strep only (in previously healthy tissue, usually strep pyogenes)
What antibiotics are used to treat nec fasc?
IV: fat must be clinically gross flucloxacillin metronidazole benzylpen clindamycin gent
Describe impetigo and its cause
golden crusty skin lesions, contagious, common in children
- caused by staph aureus
usually mild and self-limiting
What is tinea and how is it diagnosed/treated?
Superficial fungal infection of skin (ring worm, athletes foot) or nails
Diagnose with skin scrapings and treat with antifungal creams (-azoles)
What is pityriasis rosea?
Common rash in young adults, cause unclear
may be prodromal cold symptoms
usually herald patch and then christmas tree rash
usually self resolving but may need anti-itch and steroid creams
Describe vitiligo hypopigmentation
an acquired pigmentation disorder, usually symmetrical
immune destruction of melanocytes = less melanin
Describe eczema (dermatitis) and its various subtypes
Itchy, dry, sore red skin
- atopic: linked to allergy
- seborrheic: over skin with sebacious glands
- discoid: circular patches
- varicose: gravitational
- contact: delayed T4 hypersensitivity reaction
- pompholyx: restricted to hands/feet
What is the pathophys behind dermatitis and its presentation?
abnormal filaggrin expression, impaired skin barrier function, increased exposure to foreign antigens, triggers immune mediated response
S/Sx:
- vesicles and papules
- pruritis
- xerosis
- flexural involvement!!!!!!
- erythema
- scaling
How is dermatitis treated?
emollients topical steroids oral Abx antihistamines immunosuppression UV light therapy
Describe psoriasis and its subtypes
Chronic immune mediated inflammatory condition
20% pts get arthritis
Types:
- plaque
- guttate -> tear shaped, after strep throat infection!
- pustular
- erythrodermic
- flexural/inverse -> in genitals/skin folds
- koebner phenomenon -> develops on healthy skin at site of cutaneous injury
- palmar/plantar pustulosis
Describe the pathophysiology of psoriasis
Hyperproliferation -> increased turnover of skin cells and release of pro-inflammatory cytokines
Certain drugs can predispose: lithium, B blockers
What are the S/Sx of psoriasis?
Itching Burning Silvery, scaly plaques with a pinky salmon base Nail changes (pitting, onycholysis) Auspitz sign
What is the management of psoriasis
Moisturisers Topical steroids Vit D analogue/phototherapy Immunosuppression Oral retinoid Coal tar Dithranol
Describe acne vulgaris and its subtypes
Skin disease affecting the sebacious glands
types:
- vulgaris (papulopustular, nodulocystic, comedonal)
- fulminans (sudden onset and systemic upset)
- rosacea
- inversus (in groin/axilla/nasal cleft)
- agminate (in middle aged/adult patients)
Describe the pathophys of acne vulgaris
Multifactorial
XS androgens in puberty
Keratinocytes do not shed properly and clog pores
Pores infected with propionibacterium acnes
What are the treatments for acne?
Salicylic acid Topical benzylperoxide Topical Abx and retinoid Oral Abx/retinoid/corticosteroidd Oral isotretinoin!
Describe rosacea, its causes and presentation:
Chronic skin condition characterised by redness, telangectasia, roughened skin and general inflammation
- cause unclear but triggers: climatic exposures, drugs…
Presents: redness, flushing, telangectasia, watery/irritated eyes, rhinophyma
Describe the two autoimmune blistering skin conditions, their causes, the differences between them and how they are treated
Bullous pemphigoiD = deep blister
Bullous pemphiguS = superficial blister
Due to autoimmune attack of the epidermal-dermal junction
Mainly affects older pts with neurological conditions! (PD, epilepsy, stroke, MS, ALS)
Presents with tense erosions and blister which are Nikolsky sign -ve
Treated with topical/oral steroids depending severity, anti-inflammatory medications, immunosuppression
What cell type is malignant in BCC?
Basal cells
Rarely metastasises/kills
What cell type is malignant in SCC?
Keratinocytes
Increased risk of mets and death
What cell type is malignant in melanoma?
Melanocytes?
What is Breslow thickness?
Breslow thickness = determines the excision margin
- melanoma in situ =5mm margin
- <1mm = 1cm
- 1-4mm = 1-2cm
- > 4mm = >2cm
What questions are important to ask about a skin lesions?
A-E assymetry border colour changes diameter enlarging/evolving
Describe the cause of alopecia and its types
Autoimmune attack of hair follicles by inflammatory CD4+ T cells causing hair loss
Scarring type (irreversible hair loss)
- discoid lupus
- syphilis
- scalp cellulitis
- tinea
Non-scarring (reversible hair loss)
- alopecia areata
- alopecia totalis (all head)
- alopecia universalis (all body)
What are the S/Sx of alopecia areata
well circumscribed areas Hair pull test +ve small white hair growth Exclamation hairs Psychological effects: - anxiety - depression - isolation
What is livedo reticularis and in what conditions would you see it?
mottled red/blue non-blanching skin lesions, associated with RA/SLE/PAN
What is acanthosis nigricans and what is it associated with?
Benign, smooth, hyperketotic plaques in intertriginous areas
Seen in DM
What is pyoderma gangrenosum and in what conditions is it seen?
Enlarging painful ulcers with purple overhanging edge
Seen in:
IBD, RA, myeloma, leukaemia
What is erythema nodosum and in what conditions is it seen?
Erythematous tender nodules over shins
Associated with IBD/TB/Sarcoidosis
In what conditions is erythema multiforme associated with?
Mycoplasmae pneumoniae, HSV
