What are the 4 types of inflammatory skin diseases and what do they look like histologically?
Psoriaform = elongated rete ridges Spongiotic = intra-epidermal oedema (eczema) Lichenoid = damaged basement membranes (lichen planus/Lupus) Vestibulobullous = blistering
What are the 3 types of vestibulobullous inflammatory skin disease?
Pemphigus
Pemphigoid
Dermatitis herpetiformis
What is the prevelance of psoriasis?
2-3%
What are the 9 environmental triggers of psoriasis?
Trauma Infection NSAIDs Beta-blockers Lithium Alcohol Sunlight (10%) Psychological stress
What is the mean age of onset of psoriasis?
28 y/o
What condition is particularly associated with psoriasis?
IBD (Crohn’s>UC)
What is the genetic risk of inheritance of psoriasis?
1 parent = 25%
2 parents = 60%
__% of psoriasis patients have a +ve family history
35%
Describe the general pathology of psoriasis
Keratinocytes under stress triggers wrongly continuing late phase would healing response
What are the 4 main histological features of psoriasis?
Chronic inflammation altered tissue structure
Hyperkeratosis
Elongation of rete ridges
Munro-micro-abscesses (neutrophils)
What are the 9 types/patterns of psoraisis?
Erythroderma Generalised pustular Plaque (m/c) Scalp psoriasis Guttate Flexural Nail Palmoplantar pustulosis Napkin psoriasis
What are 4 discussion points for a diagnostic consultation of psoriasis?
Explain/decide management
Chronic condition
Not infectious
Social/psychological problems are common
What is the primary systemic effect of psoriasis?
increased cardiovascular risk
What 3 measurements should be monitored in psoriasis for CVD?
BP
Lipids
Glucose for DM
What are the 6 main co-morbidities associated with psoriasis?
Psoriatic arthritis Metabolic syndrome Crohn's disease Cancer Depression Uveitis
What are 4 features of generalised pustular psoriasis?
Patient is systemically unwell
Sheets of small yellowish pustules
Develops on erythematous background
Spreads rapidly
Give 4 features of the lesions of chronic plaque psoriasis
Well-defined, disc shaped lesions
Red
Covered in waxy/white scale
Auspitz sign (bleeds after scale is removed)
What are the 6 areas commonly affected by chronic plaque psoriasis?
Knees Elbows Scalp Hair margin Sacrum Extensor surfaces
What are the 4 nail changes seen in psoriasis?
Pitting
Onchyolysis
Dystrophy
Subungal hyperkeratosis
What are the 2 differentials for chronic plaque psoriasis?
Psoriatic drug reaction
Hypertrophic lichen planus
What are the 4 main features of Guttate psoriasis?
Acute, symmetrical rain drop lesions
Itchy and uncomfortable
Salmon-pink papules
Can have a scaly surface
What is the primary location of Guttate psoriasis?
Trunk/limbs
What normally preceeds Guttate psoriasis?
Strep throat infection
Viral infection
What are the 2 consequences of Guttate psoriasis?
Heals completely
Goes on to chronic plaque psoriasis
What is the differential diagnosis for Guttate psoriasis?
Pityriasis roasea
What is the age range commonly affected by Guttate psoriasis?
Teens and young adults
What are the 3 main locations for flexural psoriasis?
Armpits
Sub-mammary
Natal cleft
What is the common age range for flexural psoriasis?
Elderly
What do the plaques look like in flexural psoriasis?
Smooth/glazed
What is a differential diagnosis for flexural psoriasis?
Flexural candiasis
What is psoriatic nail changes associated with?
Psoriatic arthropathy
What is the differential diagnosis for psoriatic nail changes, and how can they be distinguished?
Fungal nail infection
Send clippings for mycology
Describe palmoplantar pustular psoriasis
Yellow/brown sterile pustules on palms or soles
What is napkin psoriasis?
Well-defined eruption in nappy area of infants
__% of patients with psoriatic skin changes are affected by psoriatic arthropathy
40%
What are the 3 pieces of general advice given to those with psoraisis in terms of management?
Stop smoking
Avoid excess alcohol
Maintain an optimum weight
What are the 6 possible topical theraputics that can be used in psoriasis?
Emollients Coal tar Vitamin D analogues Dithranol Salicylic acid Topical steroids
What are the 3 therapies used for refractory psoraisis?
Phototherapy (UVB then PUVA)
Immunosuppression (methotrexate)
Immune modulation (targeted biologics)
What is the main immunosuppressant used in psoriasis?
Methotrexate
What is an example of a vitamin D analogue?
Calcipotriol
What are the 2 disadvantages of dithranol?
Can be an irritant
Stains normal skin
What must you be careful about with topical steroids and psoriasis?
Rebound psoriasis
What are the 4 treatments used for scalp psoriasis?
Greasy ointment (to soften scale)
Tar shampoo
Steroids in alcohol base or shampoo
Vitamin D analogues
What are the 2 main options for management of flexural psoriasis?
Mild/moderate topical steroids
Calcineurin inhibitors
What are the 2 effects of coal-tar in psoriasis?
Anti-inflammatory
Anti-scaling
What are the 2 advantages of vitamin D analogues?
No smell and does not stain clothing
What is the max dosage of vitamin D?
100g/week
What is the consequence of excess vitamin D analogue usage?
Systemic absorbtion causing hypercalcaemia
NICE stages of management of chronic plaque psoriasis
1 = potent corticosteroid (1/d) and vitamin D analogue (1/d) for 4 weeks
2 = vitamin D analogue twice daily if no improvement after 8 weeks
3 = Either potent corticosteroids twice daily (up to 4 months)
Or coal tar preparation 1-2/day
If no improvement after 8-12 weeks
+ regular emollients
+Short-acting dithranol if needed
What is the initial stage of chronic plaque psoriasis management?
Potent corticosteroid once/day and vitamin D analogue once/day for 4 weeks
What is the 2nd stage of chronic plaque psoriasis management if there is no improvement after 8 weeks of stage 1?
Increase vitamin D analogue to 2/day
What is the 3rd stage of chronic plaque psoriasis management if there is no improvement after 8-12 weeks?
Either give potent corticosteroid 2/day (for up to 4 months)
OR
Coal tar preparation 1-2/day
What should always be given to patients with psoriasis, regardless of their stage in treatment?
Regular emollients
What are the 2 histological hallmarks of dermatitis?
Spongiosis
Inflammatory cell infiltrate
What is the characteristic symptom of dermatitis?
Intense itch
What are the 4 main features of dermatitis?
Itchy
Ill-defined
Erythematous
Scaly
What are the 4 features of acute phase eczema?
Papulovesicular
Erythematous
Oedema/spongiosis
Ooze/scaling/crusting
What are the features of chronic eczema due to?
Chronic itching
What are the 3 main features of chronic phase eczema?
Thickening (lichenification)
Elevated plaques
Increased scaling
What type of hypersensitivity is contact allergy?
Delayed type 4 hypersensitivity
What is the cause of contact irritant dermatitis?
Chemical trauma (from soap or water)
What is the cause of atopic dermatitis?
Genetic and environmental factors resulting in inflammation
What type of hypersensitivity reaction is drug-induced dermatitis?
Either a type1 or type 4
What is present in a biopsy of drug-induced dermatitis?
Eosinophils
What is the cause of lichen simplex?
Physical trauma to the skin due to scratching
What is the cause of stasis dermatitis?
Physical trauma to the skin via hydrostatic pressure and extravasation of RBCs
Atopic dermatitis is due to impaired ____ ___ ___
Skin barrier function
What mutation can be found in some eczema patients, and what is it associated with?
Filaggrin gene mutation
= severe/earlier onset of disease
What is the normal function of filaggrin?
Breakdown on the keratin layer, with the products helping to bind water to the keratin layer (=> moisturising)
What is the effect of a mutated filaggrin gene in eczema?
Decreased AMP => dryness and increased microbe penetration to skin
What are the 2 main consequences of the defective skin barrier in eczema?
Allows access/sensitisation to allergens
Promotes colonisation by micro-organisms
What are the 5 main components of the immune system involved in the development of atopic eczema?
Th2 cells Dendritic cells Keratinocytes Macrophages Mast cells
Which 2 interleukins are associated with eczema?
IL-4 and IL-13
Describe the non-lesional skin in eczema?
Not normal
What is the classical distribution of eczema?
Flexural surfaces
What is the distribution of eczema in infants?
Cheeks and extensor surfaces
What is the general condition of the skin in eczema?
Dry
What is the diagnostic criteria for eczema?
Itching + 3 or more of:
Visible flexural rash (cheeks and extensors in infants)
History of flexural rash
Personal history of atopy (1st-degree relative if <4y/o)
Generally dry skin
Onset before 2 y/o
What are the 6 possible treatments for eczema?
Plenty of emollients (250g/w) Avoid irritants (incl. shower gels and soaps) Topical steroids Treating infections Phototherapy (UVB) Systemic immunosuppressants
What are the 2 complications of ezcema?
Staph aureus infection
Eczema herpeticum
What is the characteristic feature of staph aureus skin infection?
Golden crust
Why are atopic children much more likely to get a staph aureus infection?
They have a much higher carriage rate
What is the cause of eczema herpeticum?
Infection of eczematous rash with herpes simplex virus
What does eczema herpeticum look like?
Monomorphic, punched out lesions
What is the difference between discoid eczema and normal eczema?
Discoid = well defined (normal = ill defined)
How can you distinguish between discoid eczema and psoriasis?
Discoid eczema = flat
psoriasis = plaque => raised
What is the common complication of discoid eczema?
Staph aureus infection
What is photosensitive eczema also known as?
Chronic actinic dermatitis
What is a distinctive feature of photosensitive eczema?
Cut-off of rash at clothing lines
What are the 3 causes of varicose eczema?
Hydrostatic pressure
Oedema
Red cell extravsation
What is the medical term for cradle cap?
Seborrhoeic dermatitis
What are the 4 main causes of erythroderma?
Drugs
Lymphedemas
Psoriasis
Eczema
Why can erythroderma be so serious?
Causes electrolyte imbalance
Give 2 examples of lichenoid disorders with a marked vacuolar interface changes
Erythema multiform
Topical epidermal necrolysis
What is the prevelance of lichen planus?
0.5%
What are the 5 histological features of lichen planus?
Irregular saw tooth acanthosis
Hypergranulation
Orthohyperkeratosis
Band-like upper dermal infiltrate of lymphocytes
Basal damage with formation of cytoid bodies
Give 2 descriptions of the lesions of lichen planus
Itchy, flat topped violaceous papules
Wickham’s striae
What are the 2 extra-dermal manifestations of lichen planus?
White reticular pattern on buccal mucosa
Nail ridges
What are the 4 locations of a lichen planus rash?
Volar wrist
Forearms
Shins
Ankles
How long does lichen planus last before burning out?
12-18 months
What is the treatment of lichen planus based on?
Symptoms
What is the management for lichen planus?
Potent topical steroids
What should be given to treat very extensive lichen planus?
Oral steroids
What is pompholyx eczema?
Sudden onset of itchy, spongiotic vesicles
What are immunobullous disorders?
Diseases that have blisters as their primary feature
What is the cause of immunobullous conditions?
Autoimmune damage to adhesion points in the epidermis/dermis
What is the cause of pemphigus?
Autoimmune damage to the desmosomes
What are the 2 types of pemphigus?
Pemphigus Vulgaris
Bullous pemphigoid
What would make a pemphigus disease very severe/fatal
Affecting the resp or GI tract
What histological feature is common to all pemphigus?
Anantholysis - lysis of intercellular adhesion points
How do you differentiate between pemphigus vulgaris and pemphigoid?
Nikolsky’s sign
What is Nikolsky’s sign +ve?
If by rubbing the epidermis, the top layers come off
What is the cause of 80% of pemphigus?
Pemphigus vulgaris
What is the cause of pemphigus vulgaris?
Autoimmune destruction of desmoglein 3 via IgG auto-antibodies
What is the end result of the pathogenesis of pemphigus vulgaris?
Acantholysis
What is the presentation of pemphigus vulgaris?
Flaccid, fluid-filled blisters that form shallow erosions
What are the 5 locations most likely to be affected by pemphigus vulgaris?
Trunk Face Groin Axillae Scalp
What symptom often accompanies the blisters in pemphigus vulgaris?
Pain, but not itching
What is left behind when pemphigus vulgaris blisters rupture?
Shallow eropsions - likely to get infected
What is seen on biopsy of pemphigus vulgaris?
Intra-epidermal IgG
What is the treatment for pemphigus vulgaris?
Steroids and immunosuppressant
What is the prognosis/natural progression of pemphigus vulgaris?
Chronic self-limiting to 3-6months but high mortality if left untreated
Where is the blister in Bullous pemphigoid?
Sub-epidermal
Is acanthosis seen in pemphigoid?
No
What histological sign is pathognomonic of pemphigus?
Tombstones
What group of people is normally affected by bullous pemphigoid?
Elderly patients
What is the cause of bullous pemphigoid?
IgG antibodies react with an antigen of the hemidesmosomes (anchor basal cells to the basement membrane) => entire epidermis detaches from basement membrane
What is the presentation of bullous pemphigoid?
Tense blisters that can be preceeded by itchy, erythematous plaques/papules
Describe the distribution of bullous pemphigoid
Localised to one area
OR over trunk and limbs
How are patients when they have pemphigoid?
Generally well
Will pemphigoid affect mucous membranes?
No
What is seen on biopsy of bullous penphigoid?
Linear IgG and complement deposition around the basement membrane
Bullous pemphigoid is Nikosky’s sign ____
Negative
Describe the natural progression of pemphigoid
Self-limiting over months to years with lower mortality than pemphigus
What is the mainstay of bullous pemphigoid amangement?
Oral corticosteroids
What can be used to manage bullous pemphigoid in addition to oral steroids?
Topical corticosteroids
Immunosuppressants
Antibiotics
What do 90% of dermatitis herpetiformis patients ahve?
Coeliac disease
What HLA is associated with dermitis herpetiformis?
HLA-DQ2
What is the histological hallmark of dermatitis herpetiformis?
Papillary derma microabscesses
What is the cause of dermatitis herpetiformis?
IgA antibodies cross react with connective tissue proteins in the dermal papillae
Describe the presentation of dermatitis herpetiformis?
Intensely itchy, symmetrical lesions across the elbows, knees and buttocks