dermatology Flashcards
1
Q
what does comprehensive assessment along with dermatological diagnostic skills allow?
A
prevent or reduce internal organ damage by early diagnosis
allow detection of internal malignancy
2
Q
what are the ways in which the skin can be involved in systemic disease (with examples)?
A
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)
3
Q
when considering neoplasia, what tests may be done?
A
imaging - examine for internal organ involvement
biopsy of affected skin
4
Q
what are the 10 different routes to a diagnosis/categories of causes in diagnosis?
A
idiopathic
neoplastic
infection
inflammatory
drug-induced
autoimmune
traumatic
metabolic
genetic
5
Q
what 5 clinical assessments are undertaken in diagnosis?
A
blood tests
microbiology
imaging
skin biopsy
specific
6
Q
what blood tests may be done as part of diagnosis?
A
full blood count
renal profile
liver function tests
inflammatory markers
autoimmune serology
7
Q
what microbiology may be done as part of diagnosis?
A
viral / bacterial serology swabs for bacteria C&S, viral PCR tissue culture / PCR
8
Q
what imaging may be done as part of diagnosis?
A
internal organ involvement
vascular supply
9
Q
what skin biopsy may be done as part of diagnosis?
A
microscopy
10
Q
what specific clinical assessments may be done as part of diagnosis?
A
urinalysis
nerve conduction studies
endocrine investigations etc.
11
Q
how can an interface pattern of inflammation be described?
A
vacuoles (little white spaces) and lymphocytes along dermal epidermal junction
12
Q
where is an interface pattern of inflammation seen?
A
lupus (and others)
13
Q
what does a line along the dermal epidermal junction in an immunofluorescence assay indicate?
A
presence of autoantibodies
14
Q
what are the 2 main groups of lupus erythematosus?
A
systemic lupus erythematosus cutaneous (discoid) lupus erythematosus (overlap)
15
Q
what are the mucocutaneous diagnostic criteria for lupus erythematosus?
A
cutaneous lupus - acute cutaneous lupus -chronic oral ulcers alopecia
16
Q
what are the haematological diagnostic criteria for lupus erythematosus?
A
haemolytic anaemia thrombocytopenia leukopenia
17
Q
what are the immunological diagnostic criteria for lupus erythematosus?
A
ANA anti-dsDNA anti-Sm antiphospholipid low complement direct Coomb’s test
18
Q
what are other diagnostic criteria for lupus erythematosus?
A
synovitis serositis (pleurisy or pericarditis) renal disorder neurological disorder
19
Q
what are some features appearing on the skin in lupus erythematosus?
A
chilblains photodistributed (sun-exposed areas) erythematous rash
20
Q
what are the cutaneous manifestations of systemic lupus erythematosus?
A
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
21
Q
what are the typical features of cutaneous (discoid) lupus erythematosus?
A
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
22
Q
what is the suspected underlying disorder in a newborn with an annular rash affecting the forehead and zygomatic prominences?
A
suspected neonatal lupus (associated with Ro antibodies)
23
Q
what test is needed in a newborn with an annular rash affecting the forehead and zygomatic prominences?
A
ECG needed - 50% chance of heart block
24
Q
what is dermatomyositis?
A
autoimmune connective tissue disease
25
what is dermatomyositis generally associated with?
proximal extensor inflammatory myopathy (muscle weakness associated)
26
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
27
what are the main signs of dermatomyositis?
photo-distributed pink-violet rash favouring scalp, periocular regional and extensor surfaces
28
how can autoantibody profiles be used in dermatomyositis?
subtypes with clinical features can be predicted by autoantibody profile
29
what does anti Jo-1 indicate in dermatomyositis?
fever myositis Gottron’s papules
30
what does anti SRP indicate in dermatomyositis?
necrotising myopathy
31
what does anti Mi-2 indicate in dermatomyositis?
mild muscle disease
32
what does anti p155 indicate in dermatomyositis?
associated with malignancy (in adults)
33
what does anti p140 indicate in dermatomyositis?
juvenile, associated with calcinosis
34
what does anti SAE indicate in dermatomyositis?
may suggest muscles are spared
35
what does anti MDA5 indicate in dermatomyositis?
interstitial lung disease digital ulcers/ischaemia
36
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
37
why is IgA vasculitis dangerous?
looks like any other small vessel vasculitis can cause progressive renal failure (follow carefully if haematuria or proteinuria)
38
what are the types of cutaneous small vessel (leukocytoclastic) vasculitis?
idiopathic infectious medication exposure inflammatory (connective tissue disease
39
what are the special types of small vessel vasculitis?
IgA Vasculitis (Henoch-Scholein) urticarial vasculitis acute haemorrhagic oedema of infancy erythema elevatum diutinum
40
what are the types of cryoglobulinemia?
type II and III
41
what are some conditions where small and medium vessels are affected?
cryoglobulinemia ANCA-associated vasculitis
42
what are the types of ANCA-associated vasculitis?
EGPA (Churg-Strauss) microscopic polyangiitis GPA (Wegener)
43
what is a condition that affects medium vessels?
polyarteritis nodosa (PAN)
44
what are the 2 types of polyarteritis nodosa (PAN)?
benign cutaneous form systemic form
45
what are some examples of large vessel conditions?
temporal arteritis tayakasu
46
how does small vessel vasculitis usually manifest?
purpura (macular/palpable)
47
how does medium vessel vasculitis usually manifest?
digital necrosis retiform purpura ulcers subcutaneous nodules along vessels
48
what are the signs and symptoms of granulomatosis with polyangitis (ANCA-associated vasculitis)?
cough, dyspnoea, and chest pain pulmonary infiltrates glomerulonephritis
49
what are the small vessel manifestations of granulomatosis with polyangitis (ANCA-associated vasculitis)?
purpura (macular/flat or popular /palpable)
50
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
51
what is sarcoidosis?
systemic granulomatous disorder affects multiple organs (commonly lungs)
52
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
53
what does histology show in sarcoidosis?
non-caseating epithelioid granulomas
54
what possibility needs to be excluded in sarcoidosis?
possibility of infection - tissue biopsy for culture or PCR needed
55
how is underlying lung involvement evaluated in sarcoidosis?
chest x-ray further diagnostics if needed - pulmonary function tests - high resolution CT thorax
56
what is drug reaction with eosinophilia and systemic symptoms (DRESS)?
multi systemic drug reaction causes skin, solid organ and haematological disturbances
57
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)
58
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)
59
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
60
what is the underlying mechanism for drug reaction with eosinophilia and systemic symptoms (DRESS)?
not known
61
what triggers drug reaction with eosinophilia and systemic symptoms (DRESS) onset?
2-6 weeks after drug exposure
62
what are the most common symptoms of drug reaction with eosinophilia and systemic symptoms (DRESS)?
fever and rash
63
what are some drugs that may cause drug reaction with eosinophilia and systemic symptoms (DRESS)?
antiepileptics sulfonamides antibiotics minocycline ibuprofen (NSAIDs)
64
how does drug reaction with eosinophilia and systemic symptoms (DRESS) progress?
initial sites of involvement - face, upper trunk, extremities spreads downwards and inward
65
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
66
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)
67
what is Schnitzler syndrome?
late‐onset acquired autoinflammatory syndrome
68
when does urticaria manifest?
as an allergy manifestation of vasculitis chronic autoimmune disease related to lupus related to autoinflammatory syndromes due to underlying infection
69
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
70
how does Schnitzler syndrome manifest?
recurrent fever above 40°C muscle, bone, joint pain (especially over ilium or tibia)
71
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
72
how is mild Schnitzler syndrome treated?
colchicine
73
how is severe Schnitzler syndrome treated?
anakinra
74
what is graft versus host disease?
multiple organ disease (acute/chronic) occurs in 10-80% of allogenic haematopoietic stem cell transplants
75
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
76
what 3 things indicate that a rash is more likely to be graft versus host disease than a drug?
face involvement acral involvement diarrhoea
77
what is the pathogenesis of graft versus host disease?
donor-derived T-lymphocyte activity against antigens in an immunocompromised recipient
78
what organs does graft versus host disease usually affect?
skin liver GI tract
79
what is pruritis?
itching without rash suggestive of internal cause
80
what are the 2 haematological causes of pruritis?
lymphoma (may cause night sweats, weight loss, fever) polycythemia
81
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)
82
what investigations are done for pruritis?
FBC, LDH renal profile liver function tests ferritin chest x-ray HIV/hepatitis A, B, C
83
why are FBC and LDH tested in pruritis?
check haematological causes
84
why is a liver function test done in pruritis?
check cholestasis
85
why is ferritin tested in pruritis?
iron deficiency/overload
86
why is a chest x-ray done for pruritis?
general screen for lymphadenopathy, intrathoracic masses
87
what can pruritis cause?
nodular prurigo
88
what is systemic amyloidosis?
manifestation of underlying plasma cell dyscrasia
89
what is the composition of amyloid?
fibrils composed of AL protein (immunoglobulin light chains, usually λ chains)
90
what are some symptoms that may present in systemic amyloidosis?
weight loss fatigue paraesthesia dyspnoea syncopal attacks (orthostatic hypotension) (varied presentation)
91
what investigations should be done for systemic amyloidosis?
abdominal fat/rectal mucosa biopsy serum amyloid protein scintigraphy
92
how is systemic amyloidosis treated?
melphalan autologous peripheral blood stem cell transplant lenalidomide bortezomib
93
why are petechiae, purpura and ecchymoses present in systemic amyloidosis?
infiltration of vessel walls
94
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
95
what can precipitate periorbital purpura in systemic amyloidosis?
coughing Valsalva manoeuvre pinching (pinch purpura)
96
what is scurvy?
vitamin C deficiency
97
what are the features of scurvy?
spongy gingivae with bleeding and erosion petechiae, ecchymoses, follicular hyperkeratosis corkscrew hairs with perifollicular haemorrhage
98
what are petechiae?
pinprick bruising
99
what is ecchymosis?
bruising
100
what is follicular hyperkeratosis?
bumpy hair follicles
101
what is kwashiorkor?
protein deficiency
102
what are the systemic features of kwashiorkor?
hepatomegaly bacterial/fungal infections diarrhoea loss of muscle mass oedema failure to thrive
103
what are the cutaneous features of kwashiorkor?
superficial desquamation and large areas of erosion sparse, dry hair soft, thin nails cheilitis
104
why is zinc important in the body?
role in many enzymes – regulation of lipid, protein, nucleic acid synthesis roles in wound healing, antioxidant
105
how is zinc deficiency caused?
genetic (SLC39A4) acquired (triad of dermatitis, diarrhoea, depression)
106
what are the cutaneous manifestations of zinc deficiency?
erythema scale-crusts erosions alopecia stomatitis conjunctivitis
107
where do cutaneous manifestations of zinc deficiency usually appear?
perioral acral perianal
108
why is vitamin B3 important?
required for most cellular processes
109
what does vitamin B3 deficiency cause?
pellagra
110
what are the 4 aspects of vitamin B3 deficiency?
dermatitis diarrhoea dementia death
111
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
112
what is carcinoid syndrome?
Signifies metastases of a malignant carcinoid tumour result in 5-HT secretion
113
what are the symptoms of carcinoid syndrome?
dramatic flushing diarrhoea bronchospasm hypotension
114
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)
115
what is Nikolsky's sign?
push your finger on the affected skin moving in any direction spreads problem
116
what is an example of a Nikolsky positive condition?
Stevens-Johnson syndrome/toxic epidermal necrolysis
117
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
118
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
119
what conditions can resemble Stevens-Johnson syndrome/toxic epidermal necrolysis?
Staphylococcal scalded skin syndrome (SSSS) thermal burns cutaneous graft versus host disease
120
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
121
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
122
what is erythroderma?
generalized erythema affecting \> 90% BSA
123
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
124
what are the systemic manifestations of erythroderma?
peripheral oedema tachycardia loss of fluid and proteins disturbances in thermoregulation risk of sepsis
125
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%)
126
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
127
what is calciphylaxis?
calcium blocks arteries
128
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)
129
what are some cutaneous primary disease signs of chronic kidney disease?
ANCA-associated vasculitis systemic lupus erythematosus
130
what are some cutaneous immunosuppression signs of chronic kidney disease?
viral warts (related to immunosuppression in renal transplant) skin cancer
131
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
132
what is necrobiosis lipoidica?
plaques with red-brown raised edge with yellow-brown atrophic centre usually patient has underlying diabetes mellitus
133
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
134
how does hyperlipidaemia manifest cutaneously?
eruptive xanthoma
135
what is a cutaneous manifestation of Graves' disease?
pre-tibial myxoedema
136
what is a cutaneous manifestation of Addison's disease?
hyperpigmentation of skin and gums
137
what endocrine disorders can acne be a cutaneous manifestation of?
acromegaly Cushing’s syndrome polycystic ovarian syndrome
138
what is a cutaneous manifestation of acromegaly?
cutis gyrata verticis (thickened skin on scalp with 'brain' like appearance)
139
what are some cutaneous manifestations of immunosuppression?
seborrhoeic dermatitis viral warts Norwegian scabies severe psoriasis bacillary angiomatosis eosinophilic folliculitis cytomegalovirus ulceration
140
what is seborrhoeic dermatitis/seborrhoeic eczema?
greasy scales on background of erythema around hair bearing sites
141
what are some cutaneous manifestations of HIV?
penicillinosis tinea corporis and faciei cryptococcosis kaposi sarcoma
142
what are some cutaneous manifestations of HIV during the seroconversion phase?
morbilliform rash urticaria erythema multiforme oral/genital ulceration
143
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
144
what are some cutaneous manifestations of inflammatory bowel disease?
panniculitis (extending ulceration due to neutrophilic inflammation) pyoderma gangrenosum orofacial granulomatosis
145
how does dermatitis herpetiformis manifest?
itchy blisters of extensor surfaces usually blisters are scratched away leaving erosions
146
how does hidradenitis suppuritiva manifest?
inflamed nodes sterile abscess sinus tracts fistulae hypertrophic scars
147
which areas does hidradenitis suppuritiva usually manifest in?
intertriginous zones especially axillary, anogenital and inframammary
148
how does pyoderma gangrenosum progress?
starts with pustule on an erythematous base ulcerates and extends with necrotic undermined border
149
what are some conditions associated with pyoderma gangrenosum?
inflammatory bowel disease leukemia seronegative arthritis (50-70% of cases)
150
what are some cutaneous manifestations of coeliac disease?
dermatitis herpetiformis
151
what skin condition is a malignancy reflecting internal malignancy?
extramammary Paget’s disease (acanthus nigrosis, Paget's disease of the nipple)
152
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
153
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)
154
what are some non-specific skin diseases that may be a manifestation of malignancy?
pruritus vasculitis urticaria
155
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
156
what are some virulence factors that are expressed by some strains of Staphylococcus?
Panton-Valentine leukocidin TSST1 (toxic shock syndrome toxin 1) exfoliative toxins
157
what are some more common manifestations of Staphylococcus skin conditions?
cellulitis impetigo folliculitis ecthyma Staphylococcal scalded skin syndrome (SSSS)
158
what other dermatoses may Staphylococcus get involved in or superinfect?
atopic eczema herpes leg ulcers etc.
159
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
160
what are some more common manifestations of Streptococcus skin conditions?
ecthyma cellulitis impetigo erysipelas scarlet fever necrotizing fasciitis
161
what other dermatoses may Streptococcus get involved in or superinfect?
leg ulcers etc.
162
what is folliculitis?
refers to inflammation of hair follicle may be infectious or non-infectious (e.g. frictional folliculitis)
163
what is eosinophilic (non-infectious) folliculitis associated with?
immune dysregulation seen in HIV
164
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)
165
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
166
how is folliculitis treated?
antibiotics (usually flucloxacillin or erythromycin) incision and drainage required for furunculosis
167
what is a furuncle?
deep follicular abscess
168
what is a carbuncle?
furuncle (deep follicular abscess) involved with adjacent connected follicles
169
what are 2 complications that may arise from carbuncles?
cellulitis septicaemia
170
what are some recurrent conditions caused by nasal reservoirs of Staphylococcus aureus?
staphylococcal impetigo recurrent furunculosis
171
what immune deficiencies may cause recurrent staphylococcal impetigo or recurrent furunculosis?
AIDS (immunocompromised) diabetes mellitus hypogammaglobulinaemia hyperIgE syndrome – deficiency chronic granulomatous disease
172
what is the mechanism by which Panton-Valentine leukocidin expresses virulence?
forms pores (β-pore-forming exotoxin) causes leukocyte destruction and tissue necrosis
173
what capabilities do Staphylococcus strains with Panton-Valentine leukocidin have?
higher morbidity higher mortality higher transmissibility
174
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)
175
what extracutaneous skin conditions are caused by Panton-Valentine leukocidin strains of Staphylococcus?
necrotising pneumonia necrotising fasciitis purpura fulminans
176
what is purpura fulminans?
form of disseminated intravascular coagulation develop widespread clotting and bleeding in the context of an infection
177
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
178
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)
179
what is pseudomonal folliculitis associated with?
associated with hot tub use, swimming pools and depilatories, wet suit
180
how is pseudomonal folliculitis treated?
most cases self limiting (no treatment) severe or recurrent - oral ciprofloxacin
181
what are some complications of psudomonal folliculitis?
follicular erythematous papule abscesses/furuncles, lymphangitis, fever
182
what is cellulitis?
infection of lower dermis and subcutaneous tissue tender swelling with ill-defined, blanching erythema or oedema
183
what are most cases of cellulitis caused by?
Streptococcus pyogenes Staphylococcus aureus
184
what is a predisposing factor for cellulitis?
oedema (e.g. elderly people, lymphoedema)
185
how is cellulitis treated?
systemic antibiotics
186
what should be checked for in a case of cellulitis?
portal of entry check for Staphylococcus in the nose, athlete's foot
187
how is cellulitis diagnosed?
no pus or exudate - no swab clinical diagnosis
188
what is impetigo?
superficial bacterial infection
189
what is the main cutaneous feature of impetigo?
stuck-on, honey-coloured crusts overlying an erosion
190
what bacteria can cause impetigo?
Streptococcus Staphylococcus
191
how can you differentiate between Streptococcus and Staphylococcus impetigo?
Streptococcus - non-bullous Staphylococcus - bullous
192
how does Staphylococcus cause bullous impetigo?
expresses exfoliative toxins A & B (virulence factors) split epidermis by targeting desmoglein I (cell adhesion molecule)
193
what areas are often affected by impetigo?
face (perioral, ears, nasal)
194
how is impetigo treated?
topical antibiotics maybe systemic antibiotics (may not work well since impetigo is superficial)
195
what is impetiginisation?
impetigo in the context of atopic eczema (gold crust) atopic dermatitis associated with Staphylococcus aureus colonisation
196
why do exfoliative toxins not need to be expressed by Staphylococcus in impetiginisation?
barrier is damaged anyway by dermatitis
197
what is ecthyma?
severe form of Streptococcal impetigo (thick crust overlying punch out ulceration, surrounded by erythema)
198
where is ecthyma usually found?
lower extremeties
199
which demographics are most likely to suffer from Staphylococcal scalded skin syndrome (SSSS)?
neonates, infants immunocompromised adults
200
what causes Staphylococcal scalded skin syndrome (SSSS)?
exfoliative toxin builds up in body infection occurs at distant site (e.g. conjunctivitis, abscess)
201
how does Staphylococcal scalded skin syndrome (SSSS) manifest?
widespread denudation of superficial skin layers
202
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
203
how does Staphylococcal scalded skin syndrome (SSSS) progress?
diffuse tender erythema rapid progression to flaccid bullae wrinkle and exfoliate leaves oozing erythematous base
204
what are the dangers of Staphylococcal scalded skin syndrome (SSSS)?
skin failure thermoregulation, fluid barrier, protein barrier, 1st line barrier compromised
205
how is Staphylococcal scalded skin syndrome (SSSS) treated?
antibiotics support skin function
206
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
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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
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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)
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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)
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what is erythrasma?
superficial infection of Corynebacterium minutissimum
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what areas are usually affected by erythrasma?
intertriginous areas (e.g. armpit)
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how does erythrasma manifest?
well demarcated patches initially pink, become brown and scaly
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what is pitted keratolysis?
Corynebacterium infection in feet (pitted erosions of soles)
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what are the cutaneous features of pitted keratolysis?
skin is very white and macerated distinctive pits
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how is pitted keratolysis treated?
topical antibiotics (clindamycin)
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why is pitted keratolysis diagnosed clincally?
does not grow on swabs (fastidious)
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what is erysipeloid?
erythema and oedema of the hand (looks like cellulitis) extends slowly over weeks
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what causes erysipeloid?
Erysipelothrix rhusiopathiae infection manifests after handling contaminated raw fish or meat
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how does cutaneous anthrax manifest?
necrotic ulcer - swelling and purpura - with surrounding oedema (painless) regional lymphadenopathy (pain in lymph nodes)
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what causes anthrax?
infection with Bacillus anthracis at site of contact with infected hides, bone meal or wool
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what is blistering distal dactylitis?
rare infection caused by Streptococcus pyogenes or Staphylococcus aureus
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what age group is blistering distal dactylitis most likely to manifest in?
young children
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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)
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what is erysipelas?
infection of deep dermis and subcutis
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what is the difference between erysipelas and cellulitis?
erysipelas more likely to affect upper extremities some overlap - erysipelas can affect more superficial skin too
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what causes erysipelas?
β-haemolytic Streptococci or Staphylococcus aureus
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what symptoms precede erysipelas?
malaise fever headache (systemic symptoms)
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how does erysipelas present cutaneously?
erythematous indurated plaque sharply demarcated border and a cliff-drop edge may be blisters
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what must be checked for in erysipelas?
portal of entry (e.g. tinea pedis)
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how is erysipelas treated?
IV antibiotics
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what age group is scarlet fever most likely to manifest in?
children
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what symptoms precede the cutaneous manifestations of scarlet fever?
sore throat headache malaise chills anorexia fever
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what causes scarlet fever?
upper respiratory tract infection involves erythrogenic toxin-producing Streptococcus pyogenes
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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
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what are the cutaneous symptoms of scarlet fever?
blanchable tiny pinkish-red spots on chest, neck and axillae sandpaper-like texture
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what are some complications of scarlet fever?
otitis mastoiditis sinusitis pneumonia myocarditis, hepatitis meningitis rheumatic fever acute glomerulonephritis
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how does necrotising fasciitis progress?
initial dusky induration (usually of a limb) followed by rapid painful necrosis of skin, connective tissue and muscle
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what organisms can cause necrotising fasciitis?
usually synergistic: Streptococci, Staphylococci, enterobacteriaceae and anaerobes
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how is necrotising fasciitis treated?
high index of suspicion broad-spectrum parenteral antibiotics, tailor after results of blood and tissue culture surgical debridement
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what scan can aid diagnosis of necrotising fasciitis?
MRI can show hyperintense signalling in deep fascia to support diagnosis and identify organisms responsible
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how can necrotising fasciitis manifest cutaneously?
Fournier's gangrene (scrotum)
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in which populations is Mycobacterium a cause for concern?
immunosuppressed states important cause of infection
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what are the cutaneous manifestations of a Mycobacterium marinum infection?
indolent granulomatous ulcers (fish-tank granuloma) sporotrichoid spread
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what is sporotrichoid spread?
lesions along lymphatic channels
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what are Mycobacterium chelonae and abscessus associated with?
puncture wounds, tattoos, skin trauma or surgery
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what is Mycobacteriuum ulcerans an important cause of?
limb ulceration Africa - Buruli ulcer Australia - Searle's ulcer
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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
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what causes borreliosis (Lyme disease)?
bite from Ixodes tick infected with Borrelia burgdorferi
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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
