Psoriasis Flashcards
Describe the appearance of psoriasis
Chronic, immune mediated disease
Sharply demarcated erythematous plaque with micaceous (silver) scales
How does psoriasis develop?
Polygenic predisposition + AI + environmental triggers
What genetic factor causes early onset psoriasis?
HLA-Cw6 (Chromosome 6)
What % of psoriasis suffers have a family history of both parents having psoriasis?
41%
What % of psoriasis suffers have a family history of psoriasis?
35-90%
What % of psoriasis suffers have a family history of one parent having psoriasis?
14%
What is the psoriasis susceptibility regions?
Psoriasis susceptibility regions PSORS1-9
What genetic factors are involved in psoriasis?
Hereditary
Psoriasis susceptibility regions PSORS1-9
HLA-Cw6 (Chromosome 6)
What environmental factors are known to trigger psoriasis?
– Infection – Drugs e.g. beta blockers – Trauma – scratching can induce excoriation and lesions – Sunlight - stress
Describe the histology of psoriasis
Hyperkeratosis (thickening of stratum corneum)
Neutrophils in stratum corneum (munro’s microabcesses)
Psoriasiform hyperplasia: Acanthosis (thickening of squamous cell layer) with elongated rete ridges
Dilated dermal capillaries
T cell infiltration
What are munro’s microabcesses?
Neutrophils in stratum corneum (munro’s microabcesses) seen in psoriasis
What medications are linked to causing psoriasis?
beta blockers, Ca channel blockers
What are 2 emergency forms of psoriasis?
– Erythroderma (>80% BSA covered) – emergency situation
– Pustular psoriasis – another emergency form
What is seen on the skin when you examine a psoriasis patient?
– Sharply demarcated, erythematous, papulosquamous (elevated squamous) plaques
– Numerous small, widely disseminated papules and plaques
If >80 BSA covered or pustular, clinical emergency
What is seen on the nails when you examine a psoriasis patient?
onycholysis (separation of nail from nail bed)
pitting (most common)
oil spots
Describe Koebner phenomenon
Koebner phenomenon - appearance of lesions along a site of injury
What is Woronoff’s ring?
Woronoff’s ring - blanched halo of approximately uniform width surrounding psoriatic lesions after phototherapy or topical treatments
What type of psoriasis is often seen acutely following an infection, particularly strep infection?
Guttate psoriasis
Describe chronic plaque psoriasis
Chronic Plaque Psoriasis: symmetrical, extensor surfaces
• Plaque psoriasis is the most common form of the disease and appears as raised, red patches covered with a silvery white buildup of dead skin cells.
• These patches or plaques most often show up on the scalp, knees, elbows and lower back. They are often itchy and painful, and they can crack and bleed.
Describe the appearance of Guttate psoriasis
Small (<5mm), salmon-pink (or red) spots usually appear suddenly on the skin two to three weeks after a streptococcal infection, such as strep throat or tonsillitis. The drop-like lesions are usually itchy.
What type of psoriasis affects the skin on the palms and soles, making them appear thick, scaly and red with yellowish brown lesions at the edges?
Palmo-plantar Psoriasis/pustulosis
What type of psoriasis is often associated with smoking and sterile inflammatory bone lesions?
Palmo-plantar Psoriasis/pustulosis
Describe Flexural/Inverse Psoriasis
o Less scaly – flexures cause constant friction so appear smoother
o Can be triggered or superinfected by localised dermatophyte, candidal or bacterial infection – these are also differential diagnoses. Makes it often confused with infections
o Sometimes called inverse psoriasis and describes psoriasis localised to the skin folds and genitals.
What would you suspect if a patient presents with an acute onset of generalised red, tender patches, which on closer inspection of the patches multiple yellow pustules are seen?
Pustular Psoriasis - clinical emergency
o Sterile pustules, sometimes systemic symptoms
o Generalized so not limited to palms and soles of feet
o Linked to pregnancy, rapid taper/stop steroids, hypocalcaemia, infections
o Overlap with acute generalized exanthematous pustulosis (AGEP; pustular drug eruption reaction)
What can trigger pustular psoriasis?
Linked to pregnancy, rapid taper/stop steroids, hypocalcaemia, infections
What condition overlaps with pustular psoriasis?
Overlaps with acute generalized exanthematous pustulosis (AGEP; pustular drug eruption reaction)
Describe the features of Erythrodermic psoriasis
Patient presents feeling shivery and generally unwell.
O/E More than 80% of his body surface area is erythematous, with fine scale.
Pyrexial and has a low blood pressure.
What are some differential diagnoses for psoriasis?
- Seborrhoeic dermatitis – chronic form of eczema; red itchy skin over sebaceous glands, scaly but appear more greasy (except sebopsoriasis!)
- Lichen planus - small, flat-topped, polygonal bumps that may coalesce into rough, scaly plaques on the skin. Very itchy
- Mycosis fungoides - common form of cutaneous T-cell lymphoma; non-resolving psoriasis like presentation
- Bowens disease – early sign of skin cancer, red scaly patch
- Drug eruption – squamous rash
- Infection
- Secondary syphilis – small painless sores, not scaly
- Contact dermatitis – inflammation caused by irritants
- Extramammary pagets – adenocarcinomas secondary to primary tumours, rare
What does a drug eruption look like?
Squamous rash
What treatments for psoriasis are given from your GP?
o Emollients (standard) - creams or ointment
o Soap substitutes
o Vitamin D3 analogues: inhibit epidermal proliferation
o Coal Tar creams
o Topical Steroid
o Salicylic acid (keratolytic, descaling agent) – special cases with severe scaling. Used alongside other treatments
What treatments for psoriasis are given from dermatologists?
o Crude Coal Tar - inpatient or day treatment; do patch test first and work up from 1-25% concentration if safe
o Dithranol: since 1916. Can burn.
o UVB Phototherapy (not the same as sunbed) – Guttate psoriasis
What systemic treatments can be given for psoriasis?
• Retinoid – Acitretin: not immunosuppressive
• Immunosuppression: Methotrexate or Ciclosporin
• Biologic Therapies:
– Anti-TNF: Etanercept, infliximab, adalimumab
– IL-12, 23: Ustekinumab
– IL-17: Secukinumab
Who is offered UVB phototherapy?
Guttate psoriasis
What psoriasis drug is teratogenic, with these effects persisting for years after cessation of treatment?
retinoids e.g. acitretin
What psoriasis treatment needs to be monitored as it can cause bone marrow suppression?
Methotrexate (immunomodulator)
Name some anti-TNF biologics
Etanercept, infliximab, adalimumab
What can be used to monitor progress of psoriasis treatment?
Psoriasis Area Severity Index (PASI) - most widely used tool for the measurement of severity of psoriasis. PASI combines the assessment of the severity of lesions and the area affected into a single score in the range 0 (no disease) to 72 (maximal disease).
– Surface area, plaque colour, thickness, scale
Dermatology Life Quality Index (DLQI) – questionnaire with score out of 30, with higher score meaning the bigger the effect on QOL
What diseases are associated with psoriasis?
Associated with cardiovascular disease, smoking, alcohol, the metabolic syndrome, depression, suicide, potentially harmful drug and light therapies, possibly melanoma and non-melanoma skin cancers.
