Other diseases Flashcards
What is vitiligo?
an autoimmune disease with loss of melanocytes
What is albinism?
a genetic partial loss of pigment production
What are porphyrias?
these are genetic or acquired rare diseases caused by errors of haem biosynthesis which can cause porphyrins to be produced or porphyrinogen build-up (neurotoxic)
What is acute intermittent porphyria?
- this is an acute neurotoxic reaction which is common and can be caused by drugs
- there is impaired function of porphobilinogen deaminase
What is porphyria cutanea tarda?
-this is the most common porphyria
type 1 is excess iron ie haemochromatosis
-this presents as blisters, fragility and excess hair
What is erythropoietic protoporphyria?
- pain to natural light
- prickly burning
- early childhood presentation
- caused by build-up of protoporphyrin 9 due to lack of ferrochelatase
What do acute porphyria attacks look like?
- GI symptoms
- neuropsychiatric problems
- CV problems
What causes chickenpox and shingles?
- chickenpox is caused by Varicella
- shingles is caused by herpes zoster
What is the progression of chicken pox?
starts as macule then progresses to papule
these then become vesicles with clear fluid and then pus
What are the complications of chicken pox?
- secondary bacterial infection
- pneumonitis
- haemorrhagic lesions
- scarring
- encephalitis
What are the symptoms of shingles?
- tingling or pain
- then erythema
- then vesicles
- then crusts
What distribution is shingles seen in?
dermatomal eg opthalmic, maxillary and mandibular
What is Ramsay-Hunt syndrome?
this is facial palsy in the seventh facial nerve and irritation of the eight nerve leading to deafness, vertigo and tinnitus
What do each of the types of herpes cause?
- HSV Type 1 is mainly oral lesions and half cases of genital
- HSV Type 2 is rare cause of oral and is half the cases of genital
What is herpes treated with?
Aciclovir and is confirmed by lab with a swab
What is erythema multiforme?
target lesions with erythema by drug reactions or some infections
What is molluscum contagiosum?
fleshy, firm and umbilicate nodules that are shiny
these are common in kids or can be sexually transmitted
What are warts caused by?
HPV
What is herpangina?
blistering rash on back of mouth caused by enterovirus which can be confirmed by swab or stool PCR
What is erythema infectiosum?
this is slapped cheek disease and is caused by parvovirus B19 which can come with acute arthritis in adults esp in wrists
What are the complications of erythema infectiosum?
- spontaneous abortions
- aplastic crises
- chronic anaemia
How is erythema infectiosum confirmed?
IgM antibody with antibody testing
What is Orf?
a virus of sheep that is a firm fleshy nodules on a farmer’s hand
What is seen in syphilis and what is it treated with?
primary chancre and then a secondary infection or red rash on palms and soles
treated with penicillin
What is Lyme disease caused by and what can it go on to cause?
- caused by borrielia burgdoferi
- can go on to cause heart block, nerve palsies or arthritis
How does Zika present?
mild fever, rash or headaches
What is the first sign of tuberous sclerosis?
ash-leaf macule seen with a Wood’s lamp
What are the symptoms of tuberous sclerosis?
- periungual fibromas on nail plate and ridges
- facial angiofibromas
- brain tumours
- hamartomas
- bone cysts
- Shagreen patches (oval, skin coloured lumps)
What are the genetic causes behind tuberous sclerosis?
- TSC1 and TSC2 genes which code for tuberin and hamartin
- it is high penetrance and low frequency in the population
What is the difference between common and Mendelian disorders?
common= low penetrance but high frequency Mendelian= high penetrance but low frequency
What is epidermolysis bullosa?
this is a group of skin fragility conditions
What are the main types of epidermolysis bullosa?
- simplex
- junctional
- dystrophic
(rare is EB acquisita which is autoimmune)
What is haploinsufficiency?
one copy of the gene is working so there is reduced protein production
What is dominant negative?
expression of abnormal protein interferes with normal protein
What is neurofibromatosis type 1?
- this is a condition of neurofibromas (can be pushed down through dermis) and cafe au lait macules
- plexiform neuromas are common, axillary or inguinal freckling or optic glioma
- protein involved is neurofibromine
What are the main types of immunologically mediated drug reactions?
- type 1 anaphylactic: urticaria
- type 2 cytotoxic: pemphigus or pemphigoid
- type 3 immune complex-mediated reactions: purport or rash
- type 4 cell-mediated delayed hypersensitivity: erythema or rash
What is the most common presentation of a drug eruption?
- maculopapular rash that is sometimes urticarial
- itch
- pigmentation
- pain
- photosensitivity
What is the process of most drug eruptions?
- most are exanthematous
- type 4 cell-mediated delayed
- mild is itch and fever
- more severe is SOB/wheeze and facial involvement
What drugs can cause bullies pemphigoid?
ACEI, penicillin or furosemide
What drugs are associated with fixed eruptions?
tetracycline, paracetamol and NSAIDs
this involves well-rounded plaques
How do you test for the different types of drug eruptions?
- patch test for type 4
- prick test for type 1
What are the most common drugs to cause a reaction?
- doxycycline, amiodarone, quinine and chlorpromazine
- thiazide causes UVA and UVB sensitivity
- NSAIDs cause pseudoporphyria
What can itch be mediated by?
- chemical mediators in the skin eg histamine
- nerve transmission eg unmyelinated C fibres
- CNS mediators eg opiates
What are the causes of itch?
- Pruritoceptive: skin eg inflammation or dryness
- Neuropathic: damage to central or peripheral nerves eg shingles
- Neurogenic: CNS receptors or systemic disease eg kidney disease or primary biliary cirrhosis
- Psychogenic: psychological causes with no CNS damage eg delusions of insects
What is the management of itch?
- treat if pruritoceptive
- give anti-itch such as sedative antihistamine, emollient, antidepressant or phototherapy
What role to mast cells play in itch?
- mast cells degranulate in response to stimuli
- this then causes release of preformed mediators eg proteases
- or causes synthesis of newly formed mediators eg prostaglandin D2 or leukotrienes
What is the difference in time of onset in IgE vs not?
IgE is within 2 hours
Non-IgE is longer
What is urticaria?
well-defined, erythema or whiteness, raised and smooth
What is the treatment for allergy?
epipen and antihistamines and steroids
What are the names of the other random tumours?
- dermatofibroma
- angiosarcoma
- merkel cell carcinoma
- sweat gland carcinoma
- cutaneous T or B cell lymphoma
What is toxic epidermal necrolysis?
severe, acute eruption secondary to a drug
