7.1 - The skin in systemic disease Flashcards
What different causes of dermatological conditions are there? (9)
- idiopathic
- neoplastic
- infection
- inflammatory
- drug-induced
- autoimmune
- traumatic
- metabolic
- genetic
What are examples of clinical assessments used in dermatology? (5)
- blood tests (FBC, renal profile, LFTs, inflammatory markers, autoimmune serology)
- microbiology (viral/bacterial serology, swabs for bacteria C&S, viral PCR, tissue culture/PCR)
- imaging (internal organ involvement, vascular supply)
- skin biopsy (microscopy)
- specific (urinalysis, nerve conduction studies, endocrine investigations etc)
What is a punch biopsy?
- biopsy of skin done under local anaesthetic
- cells taken and examined for inflammatory patterns/cell abnormalities to look for neoplasia
- can also look for autoantibodies through immunofluorescence
- can also be sent for tissue culture
What are the two main groups of lupus erythematosus?
- systemic lupus erythematosus
- cutaneous (discoid) lupus erythematosus
How can the diagnostic criteria for systemic lupus erythematosus be grouped? (4)
- mucocutaneous
- haematological
- immunological
- joint + organ involvement
What are the mucocutaneous diagnostic criteria for systemic lupus erythematosus? (4)
- cutaneous lupus - acute (e.g. chilblains and photodistributed erythematosus rash)
- cutaneous lupus - chronic
- oral ulcers
- alopecia
What are the haematological diagnostic criteria for systemic lupus erythematosus? (3)
- haemolytic anaemia
- thrombocytopenia
- leukopenia
What are the immunological diagnostic criteria for systemic lupus erythematosus? (6)
- ANA
- anti-dsDNA
- anti-Sm
- antiphospholipid
- low complement
- direct Coomb’s test
What are the joint and organ involvement diagnostic criteria + other diagnostic criteria for systemic lupus erythematosus? (2 + 2)
- synovitis
- serositis (pleurisy/pleuritis or pericarditis)
- renal disorder
- neurological disorder
What are some manifestations of systemic lupus erythematosus? (6)
- photodistributed rash (sun-exposed)
- chilblains
- alopecia
- livedo reticularis (net-like erythema)
- cutaneous vasculitis
- palpable purpura - small vessel cutaneous vasculitis
- subacute cutaneous lupus (SCLE) - ring-like (annular) plaques
What are some manifestations of cutaneous (discoid) lupus erythematosus? (2)
- discoid lupus erythematosus (often causes scarring)
- SCLE (subacute cutaneous lupus) - ring-like/annular plaques
What does a ring-like or annular rash on a baby indicate?
Immediate diagnosis of neonatal lupus - do ECG as there is 50% risk of heart block
What is dermatomyositis?
Autoimmune connective tissue disease
What is dermatomyositis characterised by? (2)
- proximal extensor inflammatory myopathy
- photodistributed pink-violet rash favouring scalp, periocular regional and extensor surfaces
What are some distinct clinical features of dermatomyositis? (5)
- Gottron’s papules (violaceous red plaques on MCP and DIP joints)
- ragged cuticles
- shawl sign (rash of upper trunk)
- heliotrope rash (erythema of upper eyelids)
- photosensitive erythema
Does dermatomyositis have subtypes?
Yes - subtypes with distinct clinical features that can be predicted by autoantibody profile
What different subtypes of dermatomyositis exist and what clinical features are they associated with? (7)
- anti Jo-1 (fever, myositis, Gottron’s papules)
- anti SRP (necrotising myopathy)
- anti Mi-2 (mild muscle disease)
- anti-p155 (associated with malignancy in adults)
- anti-p140 (juvenile, associated with calcinosis)
- anti-SAE (+/- amyopathic)
- anti-MDA5 (intersitital lung disease, digital ulcers/ischaemia)
What diagnostic tests do we do for dermatomyositis? (6)
- ANA (anti-nuclear AB) - often +ve
- LFT - ALT often increased
- CK and EMG (muscle involvement)
- skin biopsy
- screening for internal malignancy (imaging and tumour markers)
- dermatomyositis panel antibodies - subtype
Vasculitis - biopsy for direct immunofluorescence shows perivascular IgA autoantibodies, what is this?
IgA vasculitis (Henoch-Schonlein purpura)
What are some manifestations of IgA vasculitis? (5)
- abdominal pain
- bleeding (GI)
- arthralgia (joint stiffness)
- arthritis
- IgA-associated glomerulonephritis (may develop later, monitor)
What types of vasculitis are small vessels affected by? (2)
- cutaneous small vessel (leukocytoclastic) vasculitis
- small vessel vasculitis - special types
What are the subclassifications of cutaneous small vessel (leukocytoclastic) vasculitis? (4)
- idiopathic
- infectious
- inflammatory (connective tissue disease)
- medication exposure
What are some subclassifications of small vessel vasculitis (4)
- IgA vasculitis (Henoch-Schonlein)
- urticarial vasculitis
- acute haemorrhagic oedema of infancy
- erythema elevatum diutinum
What types of vasculitis are small and medium vessels affected by? (2)
- cryoglobulinemia
- ANCA-associated
What are some subclassifications of cryoglobulinemia?
Type II & III
What are some subclassifications of ANCA-associated vasculitis? (3)
- EGPA (Churg-Strauss)
- microscopic polyangiitis
- GPA (Wegener)
What type of vasculitis is medium vessels affected by, and what are its subclassifications?
Polyarteritis nodosa (PAN)
- benign cutaneous form
- systemic form
What types of vasculitis are large vessels affected by? (2)
- temporal arteritis
- Takayasu
What is a small vessel manifestation of vasculitis?
Purpura (macular / palpable)