Psoriasis Flashcards
What are the features of psoriatic nails?
- Periungal erythema
- Pitting
- Oil spots
- Subungal hyperkeratosis
- Onycholysis
What are differentials for a rash?
- Psoriasis
- Lichen planus
- Atopic eczema
- Sebhorroeic dermatitis
- Pityriasis versicolor
What are features of a rash to look for?
- Appearance of individual lesions
- Pattern of distribution (flexor, extensor, photoexposed)
- Involvement of other areas (nails, hair)
What is the presentation of chronic plaque psoriasis?
- Commonest clinical appearance (40%)
- Typical distribution pattern: ears, umbilicus, genitalia, nails, knees, toenails, scalp, elbows and natal cleft (above bum crack)
What is the presentation of guttate psoriasis?
- Describes small pink plaques of psoriasis seen on the trunk, often after a streptococcal sore throat
- Name comes from Latin ‘gutta’ meaning drops
- More common in younger individuals
- 1/3 of these patients > chronic plaque psoriasis
- Covering 50% of the body surface area would require referral to the dermatologist
What is the presentation of flexural psoriasis?
- Psoriasis affecting the genitalia or axillae
- These are sites of friction and do not show the typical silvery scale
- Usually the appearance is red (erythematous) and slightly shiny, but there will still be a clearly defined edge between normal and affected skin
- Patients are particularly distressed when there is involvement of the genitalia as this can cause difficulties with maintaining intimate relationships
What is the presentation of erythrodermic psoriasis?
- Psoriasis can flare-up and become very inflamed. When it covers over 90% of the body surface it is described as erythroderma (potentially life-threatening).
- The skin is red, feels hot and even painful
- There may be no clearly defined plaques
- Patients can feel unwell and become hypotensive, they should be admitted to hospital for treatment
What is the presentation of generalised pustular psoriasis?
- Rarely a patient’s psoriasis can flare, become red, hot, painful and develop pustules within the plaques
- Redness needs to be looked for carefully in patients with pigmented skin but can seen more easily when compared with normal skin
- This type of psoriais, though rarely seen, is an emergency requiring hospital admission
- The triggers is withdrawal of inappropriate use of super potent topical (used for several months over a large body surface area) or systemic corticosteroids therapy
What is psoriatic arthropathy?
- Between 5-20% of patients with psoriasis have arthropathy affecting their joints
- Arthropathy can precede (50%) or post-date (15%) the development of skin lesions
- The patterns of arthropathy fall into 5 subtypes: distal interphalangeal alone, symmetrical polyarthritis, asymmetrical oligoarthritis, arthritis mutilans, spondyloarthropathy
What are triggers for psoriasis?
- If presenting <40yrs (75%) genetic linkage with HLA-CW6 (Psors 1 gene on chromosome 6)
- If presenting 55-65 yrs (25%) - no genetic link
- Certain medications are known to trigger psoriasis - antimalarials, NSAIDs, beta blockers (non-selective), lithium and terbinafine (oral antifungal)
- Suddenly stopping steroid tablets can trigger or worsen psoriasis
- Alcohol
- Psychological stress
- Infections
- Damage to the skin
- Intense sunlight
What is used in the management of psoriasis?
- An emollient to use at least every 12hrs all over the body
- Soap substitute for the bath or shower
- Topical treatment with a vitamin D analogue for the trunk and limbs
- A mild topical steroid ointment for the face and flexures
What is the epidemiology of psoriasis?
- Most frequently presents in mid 20s but can affect patients at any age
- About 75% cases are before age 40
- Affects men and women equally
What is the pathology of psoriasis?
Skin affected by psoriasis is red and scaly. The outer layer of skin (epidermis) contains skin cells which are continuously being replaced - this normally takes between 3-4 weeks. In psoriasis, skin cells divide more quickly so that cells are both formed and shed in as little as 3-4 days. The inflammatory response is mediated via Th1 cells leading to an inflammatory cascade involving TNF alpha.
How can lifestyle factors affect psoriasis?
Obesity and smoking are associated with poor response to psoriasis treatments so exercise and being healthy weight can help.
Describe the PASI Scoring System for psoriasis
Psoriasis Area Severity Index - objectively measures disease severity completed by clinician - 0 = no disease, 72 = maximum disease. Useful for grading severity of patient’s disease at a particular point.
- Mild: 0 PASI
PASI can also objectively monitor patient’s response to treatment e.g. PASI50 (meaning 50% improvement following commencement of treatment compared to baseline) or PASI75 (75% improvement)