Dermatology Flashcards
What is the differential diagnosis for scarring alopecia?
Discoid lupus
Lichen planus
Tinea capitus
If a patient with DLE has negative autoantibodies what is their chance of developing SLE?
5% whereas 25% patients with systemic disease develop discoid lupus at some point
What are the potential side effects of chronic topical steroid applications
Telangiectasia
Skin breakdown
Ulceration
What is the management of discoid lupus?
Avoid sun Sun protection Stop smoking Topical steroids Topical tacrolimus Antimalarials Prednisolone Azathioprine/mycophenolate/cyclophosphamide
How do you treat psoriasis?
Topical
- soap substitutes eg aqueous cream
- emollient
- vitamin d analogues
- salicylic acid
- topical steroids
- coal tar
- dithranol
Photo (chemo) therapy
- Narrow band UVB given for 6 weeks
- Psoralen plas UVA (PUVA)- psoralen is applied topically or orally at time
- Risk of carcinogenesis is a long term side effect
Systemic
- methotrexate
- retinoids
- ciclosporin
Biologics
- etanercept/adalimumab/infliximab
What are the 6 clinical presentations of psoriasis?
- chronic plaque psoriasis
- Guttate psoriasis
- Hyperkeratotic palmo-plantar psoriasis
- flexural psoriasis
- erythrodermic psoriasis (risk of sepsis and CV compromise)
- Pustular psoriasis
What are the precipitating factors in psoriasis?
Physical trauma (Koebner phenomonen)
Infections (classically beta haemolytic strep)
Drugs (beta blockers, antimalarials, lithium, NSAIDs, steroids)
Stress
Alcohol
Tobacco
Climate
What are the two characteristic histological features seen in psoriasis?
Epidermal hyperplasia with squared off rete ridges
Inflammatory cell infiltrate in dermis and epidermis
How can you establish severity and functional status of patients with psoriasis?
PASI: The Psoriasis Area Severity Index: objective assessment of severity- looking at redness, scaling, thickness and area involved Max score 72
DLQI: Dermatology Life Quality Index- patient questionaire, subjective measures
How is neurofibromatosis inherited?
Autosomal dominant
WHat is the diagnostic criteria for neurofibromatosis type 1?
Presence of 2 or more of:
- > 6 cafe au lait macules (>15mm in adult)
- neurofibromas
- Freckling in axilla or inguinal regions
- > 2 Lisch nodules (eye brown spots)
- Optic glioma
- Distinctive osseus lesion- sphenoid dysplasia
- 1st degree relative with NF1
What are the symptoms with NF1?
Skin lesions- neurofibromas can undergo sarcomatous changes- exicsions
Neurological
- radicular pain (nerve compression due to neuromas)
- Visual problems (secondary to optic gliomas)
- Epilepsy (secondary CNS tumours)
- History of brain tumours
- Previous surgery (skin, nerves, spine, brain)
- Learning difficulties
Bones
- lordosis, kyphosis, dislocations
How does type 2 neurofibromatosis classically present?
Hearing loss
Tinnitus
Balance problems
Result of unilateral or bilateral acoustic neuromas
Cutaneous features far less prominent
What are the diagnostic criteria of NF2?
Bilateral 8th CN masses
or 1st degree relative with NF2 and either unilateral 8th nerve mass or 2 of: neurofibroma, meningioma, glioma, schwannoma or juvenile posterior subcapsular lenticular opacity
Name 3 causes of hypertension associated with neurofibromatosis?
Renal artery stenosis
Phaeochromocytoma
Coarctation of aorta
On which chromosomes are the genes responsible for neurofibromatosis type 1 and 2?
NF1: chromosome 17
NF2: chromosome 22
What is the most common CNS tumour occuring in NF1?
OPtic glioma
What is Crowes sign?
Axillary freckling
What is tuberous sclerosis?
Multisystem disorder characterised by the formation of harmartomas in many organs commonly the brain, skin and kidneys.
How is tuberous sclerosis inherited and how does it present?
AD
Commonly presents in childhood with epilepsy and skin changes
What are the features of tuberous sclerosis?
Ash leaf macules Adenoma sebaceum (facial angiofibromas) Shagreen patches over sacrum and back Ungual fibromas Skin tags Cafe au lait spots
Renal
- Renal angiomyolipoma- multiple benign
- polycystic kidneys
Cognitive and behavioural problems
What is vitiligo?
Acquired idiopathic disorder characterised by circumscribed de-pigmented macules and pacthcs. Functional melanocytes disappear from skin
How do you manage vitiligo?
Psychological support Camouflage Suncream Reversal: UVB, PUVA, tacrolimus, potent steroids Depigmentation with bleaching creams
What disorders are associated with vitiligo?
Autoimmune disorders Strongest is thyroid disorders - Pernicious anaemia - Addisons disease - Diabetes - Alopecia - Coeliac disease
Is vitiligo familial?
Around 36% have a positive FH so a genetic component
WHat is the histology of vitiligo?
Marked absence of melanocytes and melanin in epidermis
Can you suggest any theories for the aetiology of vitiligo?
Autoimmune destruction due to antibodies against melanocytes
- intrinsic defect in melanocytes
- reduced melanocyte survival and dysregulation of melanocyte apoptosis
- destruction of melanocytes by neurochemical substances
What is pyoderma gangrenosum?
Uncommon, recurrent condition causing skin ulceration frequently assoc with underlying disease
How do you treat pyoderma gangrenosum?
Bed rest Topical steroids High dose systemic steroids systemic therapy eg ciclosporin or dapsone Inflixumab
What systemic disease are assoc with pyoderma gangrenosum?
around 50% have assoc condition
- IBD
- Crohns disease
- Arthritis- RA
- Haematological disease: AML, CML, hairy cell leukaemia, myelodysplasia, monoclonal gammopathy
Apart from cutaneous sites, what other sites can be affected?
Mucous membranes and peristomal sites- sites of ileostomy and colostomy in UC and Crohns
Less commonly- vulva, penis, scrotum
What are the four major clinical forms of pyoderma gangrenosum?
Ulcerative
Bullous
Pustular
Superficial granulomatous
Is the histology in pyoderma gangrenosum specific?
No, non specific neutrophilic infiltration, haemorrhage and necrosis of epidermis
What is necrobiosis lipodica?
Rare, chronic skin condition associated with diabetes mellitus. Granulomatous inflammation and fibrosis appears as yellow, atrophic skin lesions almost exclusively on shins.
What proportion of patients with necrobiosis lipoidica have diabetes
Around 60%, occurs in both type 1 and type 2 but only 0.5% of patients with diabetes develop it.
What are the other skin changes assoc with diabetes mellitus?
Infections: bacterial, fungal
Ulcers: arterial, neuropathic
Diabetic dermopathy: brown, scaly indented patches in skin
Diabetic bullae: blisters which heal spontaneously
Granuloma annular
What are the signs of HHT?
Mutiple telangiectasia present on face and mouth
Pallor- anaemia
Nails- telangiectasia in nail bed
Visceral AVMs- pulmonary and hepatic bruits
- signs of high output cardiac failure due to left to right shunting between hepatic arteries and veins due to large AVM
- neurological sequalae
What are the clinical criteria for diagnosis of HHT?
Curacao criteria:
- epistaxis- spontaneous and recurrent
- Telangiectasia: multiple and in characteristic sites
- Visceral lesions: GI telangiectasia, pulmonary, hepatic, cerebral, spinal AVM
- FH: 1st degree relative with HHT
3 criteria definite, 2 criteria=possible
What are the complications of HHT?
GI haemorrhage: AVMs, angiodysplasia, telangiectasia Epistaxis Pulmonary AVM: haemoptysis Iron def anaemia Headache SAH
What is porphyria cutanea tarda?
Caused by a deficiency of enzyme uroporphyrinogen decarboxylase (UROD) leading to accumulation of porphyrins in skin and resultant photo-induced dermatitis.
Characterised by bullae, milia and scarring over sun exposed sites.
What are the pre-disposing factors in porphyria cutanea tarda?
Alcohol intake: high intake worsens conditions
History of hepatitis often assoc
History of liver problems eg haemochromatosis
Oestrogens that reduce UROD activity
How do you diagnose porphyria cutanea tarda?
Urine examination: fluresces pink/coral under woods light
24hr urine uroporphyrins
skin biopsy
If diagnosis made then consider investigating for hepatitis, iron/ferritin levels and AFP
How would you treat porphyria cutanea tarda?
Removal of contributing agents eg alcohol, oestrogen containing med
Sun avoidance
Phelbotomy (iron stores in liver inhibit UROD enzyme)
Anti-malarials- chloroquine
