Pathology Flashcards
Name an anaphylactic (Type I) cutaneous drug eruption
Urticaria
Name 2 cytotoxic (Type II) cutaneous drug eruptions
Pemphigus
Pemphigoid
Name an immune-complex mediated (Type III) cutaneous drug eruption
Purpura/rash
Name a T cell mediated delayed (Type IV) cutaneous drug eruption
Erythema/rash
Are immunologically-mediated drug reactions dose-dependent?
No
Give examples of dose dependent cutaneous reactions
Those that are “non-allergic”
e.g. eczema, psoriasis, pigmentation, cheilitis
How do majority of cutaneous drug eruptions present?
Exanthematous (maculopapular) 75-95%
What are other morphologies of cutaneous drug eruptions presentation?
Urticarial (5-10%) Pustular/bullous Pigmentation Itch/pain Photosensitivity
When do we consider drug eruptions?
Patient on meds
Develops sudden skin signs
Symmetric appearance
What affects the clearance of the reaction after drug withdrawal?
Half life of drug
Accumulation of drug in cells
Cross reaction with other substances
What age group is most affected?
Young adults
Which sex is most affected?
Females
Name 3 drugs associated with exanthematous drug eruptions
Penicillins
Sulphonamide antibiotics
Erythromycin
(+6)
Which drugs can cause an acne eruption?
Glucocorticoids Therapeutic androgens Lithium Isoniazid Phenytoin
Which drugs can cause acute generalised exanthematous pustulosis?
- this is rare
Antibiotics
CCBs
Antimalarials
Which drugs can cause bullous pemphigoid?
ACE inhibitors
Penicillin
Furosemide
What are fixed drug eruptions?
Present as well demarcated round plaques
Red and painful
Affects hands, genitalia, lips
Which drugs can cause fixed drug eruptions?
Tetra/doxycycline
Paracetamol
NSAIDs
Carbamazepine
Give 2 examples of severe cutaneous drug eruptions
Steven Johnson’s Syndrome
Toxic Epidermal Necrolysis
Drug rxn with eosinophilia and systemic symptoms (DRESS)
Acute generalised exanthematous pustulosis (AGEP)
Give 3 examples of ACUTE phototoxic drug reactions
Skin toxicity
Systemic toxicity
Photodegradation
Give 3 examples of CHRONIC phototoxic drug reactions
Pigmentation
Photoageing
Photocarcinogenesis
What are phototoxic cutaneous drug reactions?
Non-immunological
Happens in anybody with enough photo-reactive drug+wavelength of light
Which wavelengths of light are usually implicated in phototoxic cutaneous drug reactions?
UVA
Visible light
Which 2 drugs can cause Immediate prickling with delayed erythema and pigmentation?
Chlorpromazine
Amiodarone
Which 2 drugs can cause exaggerated sunburn?
Thiazides
Quinine
Which drug can cause exposed telangectasia?
Calcium channel blockers
Which 3 drugs can cause increased skin fragility?
Naproxen
Amiodarone
Tetracycline
Which 4 investigations can be used to determine the cause of a cutaneous drug eruption?
Phototesting
Biopsy
Patch/photopatch tests
Skin prick with specific drugs
What is the most common porphyria?
Porphyria cutanea tarda (PCT)
Which enzyme is faulty in people with porphyria cutanea tarda?
Uroporphyrinogen decarboxylase
What is the typical presentation of PCT?
Blistering
Skin fragility
Hypertrichosis
Morphoea
How do you investigate for PCT?
Woods lamp
Which enzyme is faulty in people with erythropoietic protoporphyria (EPP)?
Ferrochelatase
Which porphyrin accumulates people with erythropoietic protoporphyria?
Protoporphyrin IX
Describe the presentation of EPP
Swelling
Burning/itching
What are the investigations for EPP?
Quantitative RBC porphyrins
Fluorocytes
Transaminases
What sort of radiation do people with EPP need protection against?
Visible light
How does acute intermittent porphyria present?
GI upset:
- nausea, vomitting
- constipation
What is hyperkeratosis?
Increased thickness of keratin layer
What is parakeratosis?
Persistence of nuclei in the keratin
What is acanthosis?
Increased thickness of epidermis
What is papillomatosis?
Irregular epithelial thickening
What is spongiosis?
Oedema between keratinocytes
Give 4 features of atopic eczema
Pruritus
General erythema and scaling
FLEXURAL distribution
Other atopic diseases - asthma, etc
List 3 features of chronic atopic eczema
Lichenification
Excoriation
Secondary infection (usu S. aureus)
Describe the presentation of eczema herpeticum
Monomorphic punched out lesions
Very painful
Describe the features of acne vulgaris
Open and closed comedones
Pustules/papules
Onset at puberty
Affects regions with sebaceous glands
Describe the features of rosacea
Recurrent facial flushing Visible blood vessels NO comedones Pustules seen Thickening of the skin (rhinophyma on nose)
Name 4 factors that trigger rosacea
- sunlight
- alcohol
- spicy food
- stress
Name 3 immunobullous diseases
Pemphigus
Bullous pemphigoid
Dermatitis herpetiformis
Describe the general features of pemphigus
Affects middle-ages
Desmosomes between keratinocytes lost
Responds to steroids
Majority - pemphigus vulgaris
What is desmoglein 3?
“DesmoGLUEin”
Maintains desmosomal attachments
So keeps keratinocytes together
Give 5 features of pemphigus vulgaris
Autoimmune May affect mucosa IgG antibodies attack desmoglein 3 Immune complex forms on cell surface Leads to ACANTHOLYSIS
What is acantholysis?
Lysis of intercellular adhesion sites
- common to all forms of pemphigus
What is the more common presentation of pemphigus vulgaris?
Erosions
- the vesicles burst very easily
How is pemphigus vulgaris diagnosed?
Biopsy of fresh blisters
Give 5 features of bullous pemphigoid
Subepidermal blister Tense blisters NO acantholysis IgG attack hemidesmosomes between basal cells and basement membrane Old lesions resemble pemphigus vulgaris
How is bullous pemphigoid diagnosed?
Biopsy of EARLY LESIONS
What is the immunofluorescent pattern of IgG in the immunobullous diseases
Pemphigus vulgaris: Intraepidermal
Bullous pemphigus: along the basement membrane
Give features of dermatitis herpetiformis
Autoimmune - mediated by IgA
INTENSE itch
Associated with coeliac disease
and HLA-DQ2 haplotype
What is the hallmark feature of dermatitis herpetiformis?
Papillary dermal microabscesses
What does IgA target?
Gliadin in gluten
- but crossreact with connective tissue proteins
On mucosal surfaces, how does lichen planus present?
Reticular white lines
On skin, how does lichen planus present? [6Ps]
Purple
Pruritic
Polygonal
Planar Papules and Plaques
What is the most common viral cause of erythema multiforme?
Herpes Simplex Virus
What causes molluscum contagiosum
Poxvirus
