dermatology Flashcards
what does comprehensive assessment along with dermatological diagnostic skills allow?
prevent or reduce internal organ damage by early diagnosis
allow detection of internal malignancy
what are the ways in which the skin can be involved in systemic disease (with examples)?
skin targeted as part of multi-organ systemic disease (e.g. sarcoidosis)
skin displays sign of internal disorder (e.g. flushing in carcinoid syndrome)
“tell-tale” skin conditions suggestive of underlying condition (e.g. Pyoderma gangrenosum in inflammatory bowel disease)
skin disorder may cause secondary internal organ involvement (e.g. high output cardiac failure in erythroderma)
when considering neoplasia, what tests may be done?
imaging - examine for internal organ involvement
biopsy of affected skin
what are the 10 different routes to a diagnosis/categories of causes in diagnosis?
idiopathic
neoplastic
infection
inflammatory
drug-induced
autoimmune
traumatic
metabolic
genetic
what 5 clinical assessments are undertaken in diagnosis?
blood tests
microbiology
imaging
skin biopsy
specific
what blood tests may be done as part of diagnosis?
full blood count
renal profile
liver function tests
inflammatory markers
autoimmune serology
what microbiology may be done as part of diagnosis?
viral / bacterial serology swabs for bacteria C&S, viral PCR tissue culture / PCR
what imaging may be done as part of diagnosis?
internal organ involvement
vascular supply
what skin biopsy may be done as part of diagnosis?
microscopy
what specific clinical assessments may be done as part of diagnosis?
urinalysis
nerve conduction studies
endocrine investigations etc.
how can an interface pattern of inflammation be described?
vacuoles (little white spaces) and lymphocytes along dermal epidermal junction
where is an interface pattern of inflammation seen?
lupus (and others)
what does a line along the dermal epidermal junction in an immunofluorescence assay indicate?
presence of autoantibodies
what are the 2 main groups of lupus erythematosus?
systemic lupus erythematosus cutaneous (discoid) lupus erythematosus (overlap)
what are the mucocutaneous diagnostic criteria for lupus erythematosus?
cutaneous lupus - acute cutaneous lupus -chronic oral ulcers alopecia
what are the haematological diagnostic criteria for lupus erythematosus?
haemolytic anaemia thrombocytopenia leukopenia
what are the immunological diagnostic criteria for lupus erythematosus?
ANA anti-dsDNA anti-Sm antiphospholipid low complement direct Coomb’s test
what are other diagnostic criteria for lupus erythematosus?
synovitis serositis (pleurisy or pericarditis) renal disorder neurological disorder
what are some features appearing on the skin in lupus erythematosus?
chilblains photodistributed (sun-exposed areas) erythematous rash
what are the cutaneous manifestations of systemic lupus erythematosus?
photodistributed rash cutaneous vasculitis manifesting as palpable purpura chilblains alopecia livedo reticularis (net-like pattern of redness) subacute cutaneous lupus (SCLE) - annular/semi-annular scaly erythema photodistributed
what are the typical features of cutaneous (discoid) lupus erythematosus?
scarring noticeable when it’s present on the scalp - results in alopecia as hair follicle unit is replaced by scar tissue may also have subacute cutaneous lupus (SCLE) - annular/semi-annular scaly erythema photodistributed
what is the suspected underlying disorder in a newborn with an annular rash affecting the forehead and zygomatic prominences?
suspected neonatal lupus (associated with Ro antibodies)
what test is needed in a newborn with an annular rash affecting the forehead and zygomatic prominences?
ECG needed - 50% chance of heart block
what is dermatomyositis?
autoimmune connective tissue disease
what is dermatomyositis generally associated with?
proximal extensor inflammatory myopathy (muscle weakness associated)
what are some pathognomonic signs of dermatomyositis?
Gottron’s papules - pink/violet rashes of the metacarpal, phalangeal and interphalangeal joints ragged cuticles erythema along upper trunk in shawl like distribution (“shawl sign”) heliotrope rash around eyes photosensitive erythema
what are the main signs of dermatomyositis?
photo-distributed pink-violet rash favouring scalp, periocular regional and extensor surfaces
how can autoantibody profiles be used in dermatomyositis?
subtypes with clinical features can be predicted by autoantibody profile
what does anti Jo-1 indicate in dermatomyositis?
fever myositis Gottron’s papules
what does anti SRP indicate in dermatomyositis?
necrotising myopathy
what does anti Mi-2 indicate in dermatomyositis?
mild muscle disease
what does anti p155 indicate in dermatomyositis?
associated with malignancy (in adults)
what does anti p140 indicate in dermatomyositis?
juvenile, associated with calcinosis
what does anti SAE indicate in dermatomyositis?
may suggest muscles are spared
what does anti MDA5 indicate in dermatomyositis?
interstitial lung disease digital ulcers/ischaemia
what blood tests need to be done in dermatomyositis?
ANA CK (indicate muscle involvement) skin biopsy LFT (ALT often increased) EMG or MRI screening for internal malignancy
why is IgA vasculitis dangerous?
looks like any other small vessel vasculitis can cause progressive renal failure (follow carefully if haematuria or proteinuria)
what are the types of cutaneous small vessel (leukocytoclastic) vasculitis?
idiopathic infectious medication exposure inflammatory (connective tissue disease
what are the special types of small vessel vasculitis?
IgA Vasculitis (Henoch-Scholein) urticarial vasculitis acute haemorrhagic oedema of infancy erythema elevatum diutinum
what are the types of cryoglobulinemia?
type II and III
what are some conditions where small and medium vessels are affected?
cryoglobulinemia ANCA-associated vasculitis
what are the types of ANCA-associated vasculitis?
EGPA (Churg-Strauss) microscopic polyangiitis GPA (Wegener)
what is a condition that affects medium vessels?
polyarteritis nodosa (PAN)
what are the 2 types of polyarteritis nodosa (PAN)?
benign cutaneous form systemic form
what are some examples of large vessel conditions?
temporal arteritis tayakasu
how does small vessel vasculitis usually manifest?
purpura (macular/palpable)
how does medium vessel vasculitis usually manifest?
digital necrosis retiform purpura ulcers subcutaneous nodules along vessels
what are the signs and symptoms of granulomatosis with polyangitis (ANCA-associated vasculitis)?
cough, dyspnoea, and chest pain pulmonary infiltrates glomerulonephritis
what are the small vessel manifestations of granulomatosis with polyangitis (ANCA-associated vasculitis)?
purpura (macular/flat or popular /palpable)
what are the medium vessel manifestations of granulomatosis with polyangitis (ANCA-associated vasculitis)?
retiform purpura digital necrosis livedo reticularis subcutaneous nodules distributed along blood vessels ulcers
what is sarcoidosis?
systemic granulomatous disorder affects multiple organs (commonly lungs)
what are some clinical manifestations of sarcoidosis?
(extremely variable) cutaneous manifestations in 1/3 - red-brown to violet pupules on face, lips, upper back, neck, extremities grainy, rough plaques lupus pernio (facial manifestation) ulcerative scar sarcoid erythema nodosum (inflammation of subcutaneous fat in legs) hypopigmentation
what does histology show in sarcoidosis?
non-caseating epithelioid granulomas
what possibility needs to be excluded in sarcoidosis?
possibility of infection - tissue biopsy for culture or PCR needed
how is underlying lung involvement evaluated in sarcoidosis?
chest x-ray further diagnostics if needed - pulmonary function tests - high resolution CT thorax
what is drug reaction with eosinophilia and systemic symptoms (DRESS)?
multi systemic drug reaction causes skin, solid organ and haematological disturbances
what are the most common features of drug reaction with eosinophilia and systemic symptoms (DRESS)?
rash - characteristic rash e.g. facial oedema - widespread rash (e.g. erythroderma) fever ≥ 38.5°C lymphadenopathy peripheral eosinophilia >0.7 × 109 internal organ involvement (liver, kidneys, cardiac)
how can internal organ involvement in drug reaction with eosinophilia and systemic symptoms (DRESS)?
liver (hepatitis) - most frequent cause of death kidneys (interstitial nephritis) heart (myocarditis) brain (altered consciousness/cognition) thyroid (thyroiditis) lungs (interstitial pneumonitis)
how is drug reaction with eosinophilia and systemic symptoms (DRESS) diagnosed?
(clinical examinations including serology, scoring criteria) fever lymphadenopathy ⩾ 2 sites, > 1cm circulating atypical lymphocytes peripheral hypereosinophilia internal organs involved negative ANA, hepatitis / mycoplasma, chlamydia skin involvement - >50% BSA - cutaneous eruption suggestive of DRESS e.g. facial oedema - biopsy suggestive of DRESS
what is the underlying mechanism for drug reaction with eosinophilia and systemic symptoms (DRESS)?
not known
what triggers drug reaction with eosinophilia and systemic symptoms (DRESS) onset?
2-6 weeks after drug exposure
what are the most common symptoms of drug reaction with eosinophilia and systemic symptoms (DRESS)?
fever and rash
what are some drugs that may cause drug reaction with eosinophilia and systemic symptoms (DRESS)?
antiepileptics sulfonamides antibiotics minocycline ibuprofen (NSAIDs)
how does drug reaction with eosinophilia and systemic symptoms (DRESS) progress?
initial sites of involvement - face, upper trunk, extremities spreads downwards and inward
what are the 5 types of rash morphology in drug reaction with eosinophilia and systemic symptoms (DRESS) progress?
urticated papular exanthem - widespread papules, raised morbilliform eruption erythroderma/widespread exfoliative erythema head/neck oedema erythema multiform-like
how is drug reaction with eosinophilia and systemic symptoms (DRESS) treated?
withdrawal of culprit drug corticosteroids to suppress inflammatory response (1st line, may require months of treatment)
what is Schnitzler syndrome?
late‐onset acquired autoinflammatory syndrome
when does urticaria manifest?
as an allergy manifestation of vasculitis chronic autoimmune disease related to lupus related to autoinflammatory syndromes due to underlying infection
what is usually the first sign of Schnitzler syndrome?
recurrent urticarial rash non‐pruritic urticated macules, papules or plaques particularly on trunk resolve with brownish hyperpigmentation
how does Schnitzler syndrome manifest?
recurrent fever above 40°C muscle, bone, joint pain (especially over ilium or tibia)
what symptoms are present in Schnitzler syndrome after diagnostics?
raised monoclonal IgM lymphadenopathy, hepatomegaly or splenomegaly neutrophilia elevated acute phase reactants or abnormal bone imaging
how is mild Schnitzler syndrome treated?
colchicine
how is severe Schnitzler syndrome treated?
anakinra
what is graft versus host disease?
multiple organ disease (acute/chronic) occurs in 10-80% of allogenic haematopoietic stem cell transplants
what are the typical features of graft versus host disease?
extensive rash of face, trunk and limbs – erythematous macules and papules with large areas of confluence ~60% BSA scleral icterus oral ulceration
what 3 things indicate that a rash is more likely to be graft versus host disease than a drug?
face involvement acral involvement diarrhoea
what is the pathogenesis of graft versus host disease?
donor-derived T-lymphocyte activity against antigens in an immunocompromised recipient
what organs does graft versus host disease usually affect?
skin liver GI tract
what is pruritis?
itching without rash suggestive of internal cause
what are the 2 haematological causes of pruritis?
lymphoma (may cause night sweats, weight loss, fever) polycythemia
what are the non-haematological causes of pruritis?
uraemia (renal failure) cholestasis iron deficiency or iron overload HIV / hepatitis A, B, C cancer drugs (e.g. opiates/opioids) psychogenic pruritus of old age (connections between keratinocytes is more frayed)
what investigations are done for pruritis?
FBC, LDH renal profile liver function tests ferritin chest x-ray HIV/hepatitis A, B, C
why are FBC and LDH tested in pruritis?
check haematological causes
why is a liver function test done in pruritis?
check cholestasis
why is ferritin tested in pruritis?
iron deficiency/overload
why is a chest x-ray done for pruritis?
general screen for lymphadenopathy, intrathoracic masses
what can pruritis cause?
nodular prurigo
what is systemic amyloidosis?
manifestation of underlying plasma cell dyscrasia
what is the composition of amyloid?
fibrils composed of AL protein (immunoglobulin light chains, usually λ chains)
what are some symptoms that may present in systemic amyloidosis?
weight loss fatigue paraesthesia dyspnoea syncopal attacks (orthostatic hypotension) (varied presentation)
what investigations should be done for systemic amyloidosis?
abdominal fat/rectal mucosa biopsy serum amyloid protein scintigraphy
how is systemic amyloidosis treated?
melphalan autologous peripheral blood stem cell transplant lenalidomide bortezomib
why are petechiae, purpura and ecchymoses present in systemic amyloidosis?
infiltration of vessel walls
what are the cutaneous features of systemic amyloidosis?
periorbital purpura (‘raccoon sign’) waxy, translucent or purpuric papules, nodules found on face, neck, scalp, anogenital region, digits
what can precipitate periorbital purpura in systemic amyloidosis?
coughing Valsalva manoeuvre pinching (pinch purpura)
what is scurvy?
vitamin C deficiency
what are the features of scurvy?
spongy gingivae with bleeding and erosion petechiae, ecchymoses, follicular hyperkeratosis corkscrew hairs with perifollicular haemorrhage
what are petechiae?
pinprick bruising
what is ecchymosis?
bruising
what is follicular hyperkeratosis?
bumpy hair follicles
what is kwashiorkor?
protein deficiency
what are the systemic features of kwashiorkor?
hepatomegaly bacterial/fungal infections diarrhoea loss of muscle mass oedema failure to thrive
what are the cutaneous features of kwashiorkor?
superficial desquamation and large areas of erosion sparse, dry hair soft, thin nails cheilitis
why is zinc important in the body?
role in many enzymes – regulation of lipid, protein, nucleic acid synthesis roles in wound healing, antioxidant
how is zinc deficiency caused?
genetic (SLC39A4) acquired (triad of dermatitis, diarrhoea, depression)
what are the cutaneous manifestations of zinc deficiency?
erythema scale-crusts erosions alopecia stomatitis conjunctivitis
where do cutaneous manifestations of zinc deficiency usually appear?
perioral acral perianal
why is vitamin B3 important?
required for most cellular processes
what does vitamin B3 deficiency cause?
pellagra
what are the 4 aspects of vitamin B3 deficiency?
dermatitis diarrhoea dementia death
what are the cutaneous manifestations of pellagra?
photodistributed erythema ‘Casal’s necklace’ painful fissures of the palms and soles peri-anal and perioral inflammation and erosions cheilitis and glossitis vaginitis with erosions
what is carcinoid syndrome?
Signifies metastases of a malignant carcinoid tumour result in 5-HT secretion
what are the symptoms of carcinoid syndrome?
dramatic flushing diarrhoea bronchospasm hypotension
what is the progression of Stevens-Johnson syndrome/toxic epidermal necrolysis?
preceded by flu-like symptoms abrupt onset of lesions on trunk, face, limbs dusky erythema, blisters, atypical targetoid lesions blisters merge - subsequent epidermal detachment extensive full thickness mucocutaneous necrosis <2-3 days (dermatology emergency)
what is Nikolsky’s sign?
push your finger on the affected skin moving in any direction spreads problem
what is an example of a Nikolsky positive condition?
Stevens-Johnson syndrome/toxic epidermal necrolysis
what is the difference between Stevens-Johnson syndrome and toxic epidermal necrolysis?
Stevens-Johnson syndrome - < 10% body area (10-30% SJS/TEN overlap syndrome) toxic epidermal necrolysis - > 30% body area
what causes Stevens-Johnson syndrome/toxic epidermal necrolysis?
cell-mediated cytotoxic reaction against epidermal cells drugs cause >80% of cases, may be started up to 3 weeks prior to onset of rash
what conditions can resemble Stevens-Johnson syndrome/toxic epidermal necrolysis?
Staphylococcal scalded skin syndrome (SSSS) thermal burns cutaneous graft versus host disease
how is prognosis of Stevens-Johnson syndrome/toxic epidermal necrolysis assessed?
SCORTEN - score to assess severity and likely outcome age > 40 heart rate initial % epidermal detachment serum urea, glucose, bicarbonate presence of malignancy
what are the complications of Stevens-Johnson syndrome/toxic epidermal necrolysis?
30% mortality blindness dehydration hypothermia/hyperthermia renal tubular necrosis eroded GI tract interstitial pneumonitis neutropaenia liver and heart failure
what is erythroderma?
generalized erythema affecting > 90% BSA
how do the systemic effects of erythroderma reflect impairment of skin function?
cannot thermoregulate - hypothermia loss of fluid barrier - lose fluid and proteins causes tachycardia, oedema loss of barrier protection - vulnerability to infection
what are the systemic manifestations of erythroderma?
peripheral oedema tachycardia loss of fluid and proteins disturbances in thermoregulation risk of sepsis
what are the aetiologies of erythroderma?
(any rash can cause it) (most common) drug reactions, psoriasis, atopic eczema cutaneous T-cell lymphoma – Sézary syndrome idiopathic (25-30%)
how is erythroderma managed?
treat underlying cause (e.g. treat psoriasis, withdraw drug if drug cause etc.) restore fluid and electrolyte balance, circulatory status, manage body temperature supporting skin barrier function with emollients, may contain topical steroids or antibiotics
what is calciphylaxis?
calcium blocks arteries
what are some cutaneous signs of chronic kidney disease?
nephrogenic systemic fibrosis perforating disorder conjunctival pallor (related to anaemia - also causes hair thinning) excoriations and prurigo xerosis half and half nails retiform purpura with ulcers (suggest calciphylaxis)
what are some cutaneous primary disease signs of chronic kidney disease?
ANCA-associated vasculitis systemic lupus erythematosus
what are some cutaneous immunosuppression signs of chronic kidney disease?
viral warts (related to immunosuppression in renal transplant) skin cancer
what are some cutaneous signs of chronic liver disease?
excoriations, prurigo jaundice Muehrcke’s lines of nails (paired white lines on nails) Terry’s nails (mostly white, distally dark) palmar erythema spider telangiectasia clubbing
what is necrobiosis lipoidica?
plaques with red-brown raised edge with yellow-brown atrophic centre usually patient has underlying diabetes mellitus
what are some cutaneous manifestations of diabetes mellitus?
Terry’s nails (mostly white, distally dark) granuloma annulare necropathic ulcers acanthosis nigricans xerosis xanthelesma and xanthomata skin infections
how does hyperlipidaemia manifest cutaneously?
eruptive xanthoma
what is a cutaneous manifestation of Graves’ disease?
pre-tibial myxoedema
what is a cutaneous manifestation of Addison’s disease?
hyperpigmentation of skin and gums
what endocrine disorders can acne be a cutaneous manifestation of?
acromegaly Cushing’s syndrome polycystic ovarian syndrome
what is a cutaneous manifestation of acromegaly?
cutis gyrata verticis (thickened skin on scalp with ‘brain’ like appearance)
what are some cutaneous manifestations of immunosuppression?
seborrhoeic dermatitis viral warts Norwegian scabies severe psoriasis bacillary angiomatosis eosinophilic folliculitis cytomegalovirus ulceration
what is seborrhoeic dermatitis/seborrhoeic eczema?
greasy scales on background of erythema around hair bearing sites
what are some cutaneous manifestations of HIV?
penicillinosis tinea corporis and faciei cryptococcosis kaposi sarcoma
what are some cutaneous manifestations of HIV during the seroconversion phase?
morbilliform rash urticaria erythema multiforme oral/genital ulceration
what kind of features warrant an HIV test?
persistent or atypical manifestations or common infections opportunistic infections severe manifestations of common dermatoses (e.g. psoriasis, seborrheic dermatitis) itch suggestive dermatoses e.g. eosinophilic folliculitis
what are some cutaneous manifestations of inflammatory bowel disease?
panniculitis (extending ulceration due to neutrophilic inflammation) pyoderma gangrenosum orofacial granulomatosis
how does dermatitis herpetiformis manifest?
itchy blisters of extensor surfaces usually blisters are scratched away leaving erosions
how does hidradenitis suppuritiva manifest?
inflamed nodes sterile abscess sinus tracts fistulae hypertrophic scars
which areas does hidradenitis suppuritiva usually manifest in?
intertriginous zones especially axillary, anogenital and inframammary
how does pyoderma gangrenosum progress?
starts with pustule on an erythematous base ulcerates and extends with necrotic undermined border
what are some conditions associated with pyoderma gangrenosum?
inflammatory bowel disease leukemia seronegative arthritis (50-70% of cases)
what are some cutaneous manifestations of coeliac disease?
dermatitis herpetiformis
what skin condition is a malignancy reflecting internal malignancy?
extramammary Paget’s disease (acanthus nigrosis, Paget’s disease of the nipple)
what are some genetic conditions predisposing to specific internal cancer and skin lesions?
leiomyomas predispose hereditary leiomyomatosis (predispose renal cell cancer) mucosal melanosis predisposes Peutz–Jeghers syndrome facial angiofibroma predisposes tuberous sclerosis
what are some skin conditions associated with malignancy?
Sweet’s syndrome dermatomyositis erythema gyratum repens pyoderma gangrenosum paraneoplastic pemphigus (auto immune blistering condition brought on by a malignancy)
what are some non-specific skin diseases that may be a manifestation of malignancy?
pruritus vasculitis urticaria
why is Staphylococcus an important bacterium to consider in infection?
receptors that allow it to bind to fibrin fibrin found in abundance on wound surfaces and in dermatitis
what are some virulence factors that are expressed by some strains of Staphylococcus?
Panton-Valentine leukocidin TSST1 (toxic shock syndrome toxin 1) exfoliative toxins
what are some more common manifestations of Staphylococcus skin conditions?
cellulitis impetigo folliculitis ecthyma Staphylococcal scalded skin syndrome (SSSS)
what other dermatoses may Staphylococcus get involved in or superinfect?
atopic eczema herpes leg ulcers etc.
why is Streptococcus pyogenes an important bacterium to consider in infection?
(β-haemolytic) attaches to epithelial surfaces via lipoteichoic acid portion of fimbriae has M protein (anti-phagocytic) and hyaluronic acid capsule produces erythrogenic exotoxins (virulence factor, accounts for some clinical manifestations) produces streptolysins S and O
what are some more common manifestations of Streptococcus skin conditions?
ecthyma cellulitis impetigo erysipelas scarlet fever necrotizing fasciitis
what other dermatoses may Streptococcus get involved in or superinfect?
leg ulcers etc.
what is folliculitis?
refers to inflammation of hair follicle may be infectious or non-infectious (e.g. frictional folliculitis)
what is eosinophilic (non-infectious) folliculitis associated with?
immune dysregulation seen in HIV
what may recurrent cases of folliculitis have arisen from?
nasal carriage of Staphylococcus aureus (can colonise nasal cavity and cause distant manifestations) particularly strains expressing Panton-Valentine leukocidin (PVL)
how can the different types of folliculitis be differentiated?
nasal swab to test for reservoir, swab for bacterial (microscopy, culture, sensitivity) trauma etc. for frictional follicitis
how is folliculitis treated?
antibiotics (usually flucloxacillin or erythromycin) incision and drainage required for furunculosis
what is a furuncle?
deep follicular abscess
what is a carbuncle?
furuncle (deep follicular abscess) involved with adjacent connected follicles
what are 2 complications that may arise from carbuncles?
cellulitis septicaemia
what are some recurrent conditions caused by nasal reservoirs of Staphylococcus aureus?
staphylococcal impetigo recurrent furunculosis
what immune deficiencies may cause recurrent staphylococcal impetigo or recurrent furunculosis?
AIDS (immunocompromised) diabetes mellitus hypogammaglobulinaemia hyperIgE syndrome – deficiency chronic granulomatous disease
what is the mechanism by which Panton-Valentine leukocidin expresses virulence?
forms pores (β-pore-forming exotoxin) causes leukocyte destruction and tissue necrosis
what capabilities do Staphylococcus strains with Panton-Valentine leukocidin have?
higher morbidity higher mortality higher transmissibility
what differences are there between a skin condition caused by a standard Staphylococcus strain and Panton-Valentine leukocidin strain?
Panton-Valentine leukocidin - painful, more than 1 site, recurrent, present in contacts (more widespread)
what extracutaneous skin conditions are caused by Panton-Valentine leukocidin strains of Staphylococcus?
necrotising pneumonia necrotising fasciitis purpura fulminans
what is purpura fulminans?
form of disseminated intravascular coagulation develop widespread clotting and bleeding in the context of an infection
what are the 5C’s that increase risk of acquiring disease (Panton-Valentine leukocidin Staphylococcus)?
Close Contact – e.g. hugging, contact sports Contaminated items , e.g. gym equipment, towels or razors Crowding –crowded living conditions such as e.g. military accommodation, prisons and boarding schools Cleanliness (of environment) Cuts and grazes – will allow the bacteria to enter the body
how is Panton-Valentine leukocidin Staphylococcus treated?
effectively and precisely (due to increased mortality, morbidity etc.) antibiotics (often tetracycline) decolonisation - chlorhexidine body wash for 7 days - nasal application of mupirocin ointment for 5 days treat any close contacts (extreme transmissibility - may be carriers but not manifesting signs)
what is pseudomonal folliculitis associated with?
associated with hot tub use, swimming pools and depilatories, wet suit
how is pseudomonal folliculitis treated?
most cases self limiting (no treatment) severe or recurrent - oral ciprofloxacin
what are some complications of psudomonal folliculitis?
follicular erythematous papule abscesses/furuncles, lymphangitis, fever
what is cellulitis?
infection of lower dermis and subcutaneous tissue tender swelling with ill-defined, blanching erythema or oedema
what are most cases of cellulitis caused by?
Streptococcus pyogenes Staphylococcus aureus
what is a predisposing factor for cellulitis?
oedema (e.g. elderly people, lymphoedema)
how is cellulitis treated?
systemic antibiotics
what should be checked for in a case of cellulitis?
portal of entry check for Staphylococcus in the nose, athlete’s foot
how is cellulitis diagnosed?
no pus or exudate - no swab clinical diagnosis
what is impetigo?
superficial bacterial infection
what is the main cutaneous feature of impetigo?
stuck-on, honey-coloured crusts overlying an erosion
what bacteria can cause impetigo?
Streptococcus Staphylococcus
how can you differentiate between Streptococcus and Staphylococcus impetigo?
Streptococcus - non-bullous Staphylococcus - bullous
how does Staphylococcus cause bullous impetigo?
expresses exfoliative toxins A & B (virulence factors) split epidermis by targeting desmoglein I (cell adhesion molecule)
what areas are often affected by impetigo?
face (perioral, ears, nasal)
how is impetigo treated?
topical antibiotics maybe systemic antibiotics (may not work well since impetigo is superficial)
what is impetiginisation?
impetigo in the context of atopic eczema (gold crust) atopic dermatitis associated with Staphylococcus aureus colonisation
why do exfoliative toxins not need to be expressed by Staphylococcus in impetiginisation?
barrier is damaged anyway by dermatitis
what is ecthyma?
severe form of Streptococcal impetigo (thick crust overlying punch out ulceration, surrounded by erythema)
where is ecthyma usually found?
lower extremeties
which demographics are most likely to suffer from Staphylococcal scalded skin syndrome (SSSS)?
neonates, infants immunocompromised adults
what causes Staphylococcal scalded skin syndrome (SSSS)?
exfoliative toxin builds up in body infection occurs at distant site (e.g. conjunctivitis, abscess)
how does Staphylococcal scalded skin syndrome (SSSS) manifest?
widespread denudation of superficial skin layers
why are infants and neonates more likely to suffer from Staphylococcal scalded skin syndrome (SSSS)?
kidneys do not function fully as yet, cannot excrete exfoliative toxin
how does Staphylococcal scalded skin syndrome (SSSS) progress?
diffuse tender erythema rapid progression to flaccid bullae wrinkle and exfoliate leaves oozing erythematous base
what are the dangers of Staphylococcal scalded skin syndrome (SSSS)?
skin failure thermoregulation, fluid barrier, protein barrier, 1st line barrier compromised
how is Staphylococcal scalded skin syndrome (SSSS) treated?
antibiotics support skin function
what is the difference between Staphylococcal scalded skin syndrome (SSSS) and Stevens-Johnson syndrome/toxic epidermal necrolysis?
(clinically resemble each other) entire epidermis comes off in Stevens-Johnson syndrome/toxic epidermal necrolysis, only superficial layer in SSSS less severe consequences in SSSS if they survive
what is toxic shock syndrome?
(not a skin condition, manifests in skin) febrile illness group A Staphylococcus aureus strain that produces pyrogenic exotoxin TSST-1
what are the symptoms of toxic shock syndrome?
fever >38.9°C hypotension may involve: - GI - muscular - CNS - renal - hepatic - haematological (platelets < 100 000 per mm3)
how does toxic shock syndrome manifest cutaneously?
mucous membranes - diffuse erythema 1-2 weeks after resolution of erythema - desquamation predominantly of palms and soles (skin recovery - peeling off dead layers)
what is erythrasma?
superficial infection of Corynebacterium minutissimum
what areas are usually affected by erythrasma?
intertriginous areas (e.g. armpit)
how does erythrasma manifest?
well demarcated patches initially pink, become brown and scaly
what is pitted keratolysis?
Corynebacterium infection in feet (pitted erosions of soles)
what are the cutaneous features of pitted keratolysis?
skin is very white and macerated distinctive pits
how is pitted keratolysis treated?
topical antibiotics (clindamycin)
why is pitted keratolysis diagnosed clincally?
does not grow on swabs (fastidious)
what is erysipeloid?
erythema and oedema of the hand (looks like cellulitis) extends slowly over weeks
what causes erysipeloid?
Erysipelothrix rhusiopathiae infection manifests after handling contaminated raw fish or meat
how does cutaneous anthrax manifest?
necrotic ulcer - swelling and purpura - with surrounding oedema (painless) regional lymphadenopathy (pain in lymph nodes)
what causes anthrax?
infection with Bacillus anthracis at site of contact with infected hides, bone meal or wool
what is blistering distal dactylitis?
rare infection caused by Streptococcus pyogenes or Staphylococcus aureus
what age group is blistering distal dactylitis most likely to manifest in?
young children
what are the cutaneous manifestations of blistering distal dactylitis?
1 or more tender superficial bullae on erythematous base on volar fat pad of a finger (toes may rarely be affected)
what is erysipelas?
infection of deep dermis and subcutis
what is the difference between erysipelas and cellulitis?
erysipelas more likely to affect upper extremities some overlap - erysipelas can affect more superficial skin too
what causes erysipelas?
β-haemolytic Streptococci or Staphylococcus aureus
what symptoms precede erysipelas?
malaise fever headache (systemic symptoms)
how does erysipelas present cutaneously?
erythematous indurated plaque sharply demarcated border and a cliff-drop edge may be blisters
what must be checked for in erysipelas?
portal of entry (e.g. tinea pedis)
how is erysipelas treated?
IV antibiotics
what age group is scarlet fever most likely to manifest in?
children
what symptoms precede the cutaneous manifestations of scarlet fever?
sore throat headache malaise chills anorexia fever
what causes scarlet fever?
upper respiratory tract infection involves erythrogenic toxin-producing Streptococcus pyogenes
when do cutaneous symptoms of scarlet fever manifest?
first manifest 12-48 hours after preceding symptoms (fever, malaise etc.) spreads to body within 12 hours
what are the cutaneous symptoms of scarlet fever?
blanchable tiny pinkish-red spots on chest, neck and axillae sandpaper-like texture
what are some complications of scarlet fever?
otitis mastoiditis sinusitis pneumonia myocarditis, hepatitis meningitis rheumatic fever acute glomerulonephritis
how does necrotising fasciitis progress?
initial dusky induration (usually of a limb) followed by rapid painful necrosis of skin, connective tissue and muscle
what organisms can cause necrotising fasciitis?
usually synergistic: Streptococci, Staphylococci, enterobacteriaceae and anaerobes
how is necrotising fasciitis treated?
high index of suspicion broad-spectrum parenteral antibiotics, tailor after results of blood and tissue culture surgical debridement
what scan can aid diagnosis of necrotising fasciitis?
MRI can show hyperintense signalling in deep fascia to support diagnosis and identify organisms responsible
how can necrotising fasciitis manifest cutaneously?
Fournier’s gangrene (scrotum)
in which populations is Mycobacterium a cause for concern?
immunosuppressed states important cause of infection
what are the cutaneous manifestations of a Mycobacterium marinum infection?
indolent granulomatous ulcers (fish-tank granuloma) sporotrichoid spread
what is sporotrichoid spread?
lesions along lymphatic channels
what are Mycobacterium chelonae and abscessus associated with?
puncture wounds, tattoos, skin trauma or surgery
what is Mycobacteriuum ulcerans an important cause of?
limb ulceration Africa - Buruli ulcer Australia - Searle’s ulcer
how does borreliosis (Lyme disease) initially manifest?
erythematous papule at site of bite - central redness, concentric less bright redness, outer red ring progress to annular erythema > 20cm
what causes borreliosis (Lyme disease)?
bite from Ixodes tick infected with Borrelia burgdorferi
how can borreliosis (Lyme disease) progress if left untreated?
1-30 days after infection - fever, headache multiple secondary lesions develop - similar but smaller to initial lesion neuroborreliosis - facial palsy / other CN palsies - aseptic meningitis - polyradiculitis arthritis – knee most affected joint carditis
