Dermatology Flashcards
What is bullous pemphigoid
Autoimmune sub-epidermal condition characterised by large, tense blisters found on the limbs, trunks and flexors
Bullae/erosions may be also found on oral/genital mucosa
What autoantibodies are present in bullous pemphigoid
BP antigen II and I
Treatment of bullous pemphigoid
Steriods
Supportive measures
Risk factors for developing bullous pemphigoid
Previous chronic inflammatory skin conditions (e.g. lichen planus or psoriasis)
Drugs
- furosemide
- antibiotics
- NSAIDs
Neurological disease
- PD
- dementia
- Epilepsy
Causes of bullous eruptions
Congenital
Strep infection
Staph scalded skin syndrome
TEN
Diabetic bullae
CKD
Haemodialysis
Barbituate overdose
Immunological
What is erythema multiforme?
Presents as eruptions of multiple lesions, which are maculopapular, target shaped rashes but can appear in various forms (hence the name multiforme)
Where can erythema multiforme occur?
Anywhere on the body
Palms
Soles
Oral mucosa
What may there be a history of with erythema multiforme?
Viral illness
Where does the rash usually start and spread with eyrthema multiforme?
Starts distally
Spreads proximally
What is Koebeners phenomenon?
Lesions appearing on areas of previous skin trauma
Differentials of erythema multiforme
Insect bites
SJS
TEN
Drug eruption
Dermatitis
Bullous pemphigoid
Pemphigus
Dermatitis herpetiformis
What is neurofibromatosis?
A genetic condition characterised by lesions of the skin, CNS and skeleton
Types of neurofibromatosis
Type I
Type II
Schwannomatosis
Genetics of neurofibromatosis type I
Autosomal dominant inherited disorder
Caused by mutation in the neurofibromin gene (NF1) on chromosome 17
Presentation of NF1
Often presents in first year of life and increase in number with age
Leads to multiple tumours that grow along the NS anywhere in the body
Skin lesions
- multiple neurofibromas (skin coloured lesions) and cafe au lai macules
- freckling, particularly in skin folds
Neuro dermatofibromas arise from nerve trunks and can cause paraesthesia when pressed
Lisch nodules (seen on eye with slit lamp)
Short stature
Macrocephaly
Around 30% develop
- Mild learning disability
- Acoustic neuromas
- epilepsy
Rare assosiation of NF1
Phaechoromocytoma
Main difference NF2 vs NF1
CNS tumours being more characteristic than skin lesions
Presentation of NF2
Bilateral acoustic neuromas are characteristic
Meningiomas
Glial cell tumours
Usually present with deafness in their 20s; tinnitus, veritgo
Genetics of NF2
Mutation found on chromosome 22
Can be autosomal dominance or de novo (up to 50%)
Treatment of acoustic neuroma
Surgical excision
Mean survival from diagnosis of NF2
15 years
What is schwannomatosis?
Occurence of multiple tender cutaneous schwannomas without the vestibular neuroma assosiated with NF2
Often a very large tumour load requiring assessment with MRI
Is life expectancy affected in schwannomatosis?
No
Which NF is more common?
Type 1
Presendation of schwannomatosis
Pain
Related or unrealated to masses
Paraesthesia and weakness
Genetics of schwannomatosis
Medatiations of tumour suppression genes such as SMARCB1 and LZtr1
Complications of NF
Tumours of optic nerves (gliomas) (15% of childre with NF1)
Scoliosis
Osteoporosis
Epilepsy
Increased risk of brain tumours, leukaemias and other malignancies of neural crest origins
Malignant change if there are peripheral sheath tumours in NF1 (assosiated with poor survival)
First line treatment for scabies
Permethrin cream
What is erythema nodosum
Acute panniculitis (inflammation in the fat) that produces tender nodules or plaques on the shins and occassionally elsewhere
Assosiations of erythema nodosum
Idiopathic
Sarcoidosis
Pregnancy
IBD
Strep infections
TB
Treatment with sulfonamides or OCP
Treatment of erythema nodosum
NSAIDs
What is pyroderma gangronosum assosiated with
IBD
Vasculitis
Haematological malignancy
Presentation of pyoderma gangrenosum
Deep ulcer
Violet border
What is koebeners phenomenon
New disease lesions develop at the site of skin injury
What coniditons provide a true koebeners response
Psoriasis
Vitiligo
Lichen planus
Rash in lichen planus
Pigmented
Itchy
Diseases assosiated with PLEVA
Toxoplasmosis
EBV
HIV
CMV
Parovirus
Staph A septicaemia
Group A beta haemolytic strep infection
Presentation of PLEVA
Initial area of erythema
Develops rapidly into multiple pus filled papules
What is onchyolysis
Seperation of nail bed from nail plate
Causes of onchyolysis
Psoriasis
Trauma
Infection
Drugs - tetracycliens, psoratens
Thyrotoxicosis
What is bowens disease
A form of SCC
Presents as a red scaley plaque
How does polyphyria cutanea tarda occur
Bullous eruptions after exposure to sunlight
Eruptions heal into scarring and milia
Photodistribution of the rash
Investigation of polphyria cutanea tarda
Clinically
High levels of urinary uroporphyrin
How can remission of polyphyria cutanea tarda be induced
Venesection
Presentation of rash in dermatomyositis
Red or volacious periorbital eruption known as the helitrope rash
May be assosiated oedema
Linear volacious changes over dorsal aspect of fingers
Shawl sign - erythema over upper back and posterior neck
Weakness of major proximal muscles
Investigations of scabies
Ink test
What is pemphigus vulgaris
Mucosal involvement with ulceration
Flaccid blisters (on trunk in particular)
What would be found in a biopsy for pemphigus vilgaris
Intercellular IgG deposition
What is the test for marfan syndrome
Fibrillin 1 (FBN1) gene testing
What is pseudoxanthoma elasticum
Rare genetic disease causing systemic calcium deposition and fragmentation of elastic tissue
Complications of pseudoxanthoma elasticum
Central blindness
CVS events
GI bleeding
Skin manifestations of pseudoxanthoma elasticum
Multiple small yellow papiles, possibly joining into larger patcges
Later in the disease, skin can become lax, wrinkled and hanging in like fold like appearances e.g. on upper arms
on neck (commonest), inside elbows, back of knees, umbilicus, groin
Oral, genital and rectal mucosa
Diagnosis of pseudoxanthoma elasticum
Skin biopsy
Drugs that can cause photosensitivity
Doxycycline
NSAIDs
retinoids
Diuretics
CVS drugs (amoidarone, enalapril, quinidine, diltiazem)
Sulfounryea drugs
Phenthoiazines
What can immunosuppresision cause in relation to shingles?
Muti-dermatomal
Disseminated disease
In the pathogenesis of psoriasis, which cell type is most implicated in the inflammatory response
T lymphocytes
What drugs can worsen psoriasis
Beta blockers
Anti-malarials
Lithium
Withdrawl of oral corticosteriods, especially if sudden
What can precipitate guttate psoriasis
Strep infection
What is melasma
Hormonally stimulated increase in melaogensis that mainly appears on the face
What can worsen melasma
Sun exposure
COCP
Pregnancy
Where does melasma occur mainly
On the face
Secondary syphillis presentation
Polymorphic rash
- particularly on palms and soles of feet
Presentation of primary syphillis
Painless ulcer
What causes pellagra
Chronic vitamin B3 deficiency
Presentation of pellagra
3Ds
- photosensitive dermatitis
- diarrhoea
- dementia
What condition can pellagra be seen in
Carcinoid syndrome
Skin manifestations of systemic sclerosis
Taunt, shiny skin
Telangiectasis
Salt and pepper discolouration
Ulceration
Sclerodactyly
What is necrobiosis lipoidica
Unusual complication of DM
May also occur in non diabetic patients
Small vessel damage leads to partial necrosis of detmal colleagen and connective tissue, with a histiocytic cell response