Lichenoid Disorders Flashcards
What is meant by a lichenoid disorder?
clinically - shiny flat topped itchy papular rash
histologically - band like inflammatory infiltrate in the upper dermis with basal cell necrosis
Name four lichenoid disorders
- lichen planus
- drug eruptions
- graft vs host disease
- pityriasis lichenoides
What is the name given to the appearance of basal cell necrosis?
Civatte bodies
Describe the aetiology of Lichen Planus
Genetic association & links to hepatitis C, T cell mediated autoimmune inflammatory condition
Describe the histological appearance of lichen planus
Acanthosis (irregular saw tooth thickening of epidermis) civatte bodies with lymphocytic infiltrate
Name the different types of lichen planus
Hypertrophic
Atrophic
Follicular
Mucosal
How does lichen planus present?
Shiny flat topped violaceous polygonal papules often very itchy
What is the name for the white lines with a lace like patten on surface of papules and bullae?
Wickham’s striae
How is Lichen Planus managed?
Can clear spontaneously but treatment is symptomatic and potent topical steroids. If unresponsive systemic therapies may be required.
What are the four types of immune mediated reactions?
I - anaphylactic
II - cytotoxic reactions
III - immune complex mediated
IV - cell mediated delayed
For each of the immune mediated reactions what is the typical corresponding dermatological presentation?
I - Urticaria
II - Pemphigus and Pemphigoid
III - Purpura/rash
IV - erythema/rash
Name the risk factors for a drug eruption
- age
- gender
- genetics
- concomitant disease (virus/CF)
- immune status
- drugs
What is the most common type of drug eruption?
Exanthematous type 4 hypersensitivity reaction
How does exanthematous type 4 hypersensitivity reaction present?
Widespread symmetrical rash with no mucosal involvement can be itchy but often associated with a mild fever, 4-21 days after taking first dose
What are the indications of a severe exanthematous reaction?
- mucous/fascial involvement or oedema
- confluent erythema
- SOB/Wheeze/Lymphadenopathy
- Blisters, purpura, necrosis
What antibiotics can cause an exanthematous reaction?
SEPS sulphonamides erythromycin penicillin streptomycin
What anti-epileptic drugs can cause an exanthematous reaction?
Carbamazepine
Phenytoin
Other than anti - biotic and epileptic drugs what can cause an exanthematous drug eruption?
allopurinol
NSAIDs
chloramphenicol for conjunctivitis
When can a type 1 hypersensitivity reaction occur?
First exposure - direct release of inflammatory mediators from mast cells
Re-challenge with drug
Which drugs can cause a direct mast cell degranulation and thus anaphylactic shock?
Morphine
NSAIDs
Codeine
Aspirin
Which drugs can cause an IgE response and thus anaphylactic shock?
Penicillins
Cephalosporins
Name three drugs that can cause exanthematous pustulosis
Antibiotics, Calcium channel blockers, antimalarials
What drugs can induce bullous pemphigoid?
ACE inhibitors, penicillin, furosemide
What drug eruption can happen from glucocorticoids?
Acneform no increased sebum or comedones
Describe fixed drug eruptions
Lesions occur in the same area each time a particular drug is taken - well demarcated round/ovoid plaques are red and painful
Name some common drugs that cause fixed drug eruptions
- tetracycline/doxycycline
- paracetamol
- NSAIDs
- Carbamazepine
Name four very severe drug reactions
Stevens Johnson Syndrome
Toxic Epidermal Necrolysis
Drug Reaction with eosinophilia and systemic symptoms (DRESS)
Acute generalised ezanthemaouts pustolosis (AGEP)
Describe Steven Johnson Syndrome
Life threatening much-cutanous exfoliation, severe variant of erythema multiform that leads to systemic complications
What are the extra-cutaneous manifestations of SJS?
Stomatitis, oesophagitis, diarrhoea, painful micturition, desquamation of respiratory tract
Describe Toxic Epidermal Necrolysis
Widespread erythema followed by epidermal necrosis with loss of large sheets of epidermis
Where must patients with TEN be managed?
HDU/Burns Unit
What is the biggest risk to patients with TEN?
Multi-organ failure due to loss of thermoregulation
What drugs can cause SJS and TEN?
Anti-biotics NSAIDs Anticonvulsants Anti-retroviral medication Opiates
How are SJS and TEN managed?
Withdraw underlying cause
Prevent complications
Fluid and electrolyte replacement
Systemic antibiotics if evidence of infection
Emollients
TEN - IV immunoglobulins improve prognosis
What is a phototoxic drug reaction?
Some drugs will absorb UV, the drug will act as a chromophore leading to non-immunoligcal reactions if a patient is exposed to enough drug & light
Describe the features of acute phototoxic drug reactions
- photosensitivity
- systemic toxicity
- photo degradation
Describe the features of chronic phototoxic drug reactions
- pigmentation
- photo ageing
- photocarcinogenesis
What drugs would cause immediate prickling with delayed erythema?
Chlorpromazine and amiodarone
What drugs would cause exaggerated sunburn?
Quinine and thiazides
What drug would cause exposed telangiectasia?
CCBs
What drug would cause delayed pigmentation/erythema?
Psoralens
What drugs would cause increased skin fragility?
Tetracycline, naproxen, amiodarone
What reaction would azathioprine cause?
?
How should drug eruptions be managed?
Discontinue drug if severe
Topical steroids
Anti-histamine if Type 1
Allergy bracelet/yellow card scheme
