Basics of Psoriasis for Medical Students

Basic psoriasis for medical students. Basic pathology, morphology and treatments

1. PSORIASIS

2. Introduction & Epidemiology 04 TABLE OF CONTENTS 06 01 03 Clinical Features & Variants Assessment & Investigations Monitoring & Prognosis 02   Aetiology & Pathophysiology 05 Management (NICE-Aligned) PSORIASIS

3. Introduction Epidemiology 01

4. • Psoriasis = Chronic inflammatory skin disease • Characterized by red, well-demarcated plaques with silver scale • Variable severity: mild to severe forms • Prevalence : ~2% in the UK; peak onset 16–22 (early onset) & 55–60 (late onset) INTRODUCTION PSORIASIS

5. Epidemiology Psychological Comorbidities 01 02 03 depression, anxiety, impaired body image - psoriatic arthritis, metabolic syndrome, increased CV risk - Chronic, stigmatizing disease → affects quality of life, employment, relationships Epidemiology and Impact PSORIASIS ~2% of the UK population

6. Aetiology & Pathophysiology 02

7. Genetics • Polygenic inheritance : multiple susceptibility loci (PSORS1 is the main) • Twin studies : ~73% concordance in monozygotic twins vs. ~20% in dizygotic Environmental • Infections (especially streptococcal for guttate psoriasis) • Certain medications (beta-blockers, lithium, antimalarials) • Stress, smoking, obesity  Genetic & Environmental Factors A B PSORIASIS

8.  Immune Dysregulation Keratinocyte hyperproliferation thickened plaques with scale Chronic inflammation risk of comorbidities (e.g., cardiovascular disease) Pathogenic loop : T-cells (especially Th17 axis) ↔ dendritic cells ↔ keratinocytes Cytokine drivers :  TNF- α, IL-12/23, IL-17, IL-22 PSORIASIS

9. Clinical Features & Variants 03

10. Variants PSORIASIS Chronic Plaque Psoriasis (psoriasis vulgaris) – 90% of cases Chronic Guttate Erythrodermic PSORIASIS Inverse/flexural Pustural acute onset, small ‘rain-drop’ lesions in skin folds, shiny, less scaling  involves >90% BSA, systemic symptoms, emergency generalized or palmoplantar

11. Chronic Plaque Psoriasis • Well-demarcated, erythematous plaques with silvery scale • Common sites: extensor surfaces (knees, elbows), scalp, lower back • Köbner phenomenon: new plaques at areas of trauma

12. Guttate and Flexural Psoriasis • Guttate : triggered by strep infections, primarily in children/young adults • Often self-resolving but can evolve into chronic plaque • Flexural (Inverse): older adults, obese patients, minimal scale in folds

13. Pustular & Erythrodermic Psoriasis • Pustular • Palmoplantar or generalized (von Zumbusch ) • Precipitated by withdrawal of systemic steroids • Erythrodermic • Rare, severe, entire body involvement • Fever, malaise, hemodynamic instability

14. Nail Psoriasis • Affects ~50% of patients • Pitting , onycholysis, subungual hyperkeratosis, discoloration • Topical treatments often ineffective ; systemic or biologics might help

15. Assessment & Investigations 04

16. 01 PASI (Psoriasis Area and Severity Index) 02 DLQI  (Dermatology Life Quality Index) 03 PEST (Psoriasis Epidemiology Screening Tool) for psoriatic arthritis Assessing Severity & Impact PSORIASIS

17. Psoriatic Arthritis • Up to 40% with psoriasis may have joint involvement • Ask about joint pain, stiffness, enthesitis • Refer to rheumatology if suspicion • Use PEST or other validated tool

18. Investigations Clinical diagnosis primarily Screening obesity, metabolic syndrome, depression Biopsy if atypical presentation Blood tests monitoring for comorbidities (lipids, glucose, LFTs if on systemic therapy) 1 4 2 3 PSORIASIS

19. Management 05

20. Treatment Hierarchy Overview PSORIASIS 1. Topical therapies 2. Phototherapy (NB-UVB, PUVA) 3. Systemic Non-Biological (e.g., methotrexate, ciclosporin, acitretin) 4. Biologics (TNF- α, IL-12/23, IL-17, IL-23 inhibitors)

21. Topical therapy • First-line for mild disease or localized plaques • Agents : • Vitamin D analogues (calcipotriol) • Potent topical steroids • Coal tar, tazarotene, dithranol (less commonly used now) • Important : watch skin atrophy with long-term steroids

22. Phototherapy • Narrowband UVB = first choice for moderate-severe psoriasis not controlled by topicals • PUVA (psoralen + UVA) = second-line; watch cumulative dose → skin cancer risk • Typically for widespread or guttate psoriasis

23. Systemic Therapy • Methotrexate • First-line for moderate-severe psoriasis (PASI >10, DLQI >10) • Weekly dosing, monitor LFTs, FBC, hepatic fibrosis risk • Ciclosporin • Rapid onset, short-term use, monitor renal function, BP • Acitretin • Useful for pustular variants, teratogenic (3-year wait after stopping in women) • Mucocutaneous side effects (dryness, cheilitis)

24. Biologic Therapy • Indicated for severe psoriasis (PASI >10, DLQI >10) failing conventional systemics/phototherapy • Anti-TNF- α : adalimumab, etanercept, infliximab • IL-12/23 inhibitor : ustekinumab • IL-17 inhibitors : secukinumab , ixekizumab • IL-23 inhibitors : guselkumab , tildrakizumab, risankizumab

25. NICE Key Points on Biologics PSORIASIS • Usually used last-line unless the patient has severe, recalcitrant disease or cannot tolerate non-biologics • Baseline screening for TB, hepatitis • Must consider long-term safety → register patients in BADBIR (British Association of Dermatologists Biological Interventions Register)

26. Monitoring & Prognosis 06

27. Regular reviews Check CV risk Mental health screening 01 02 03 factors: obesity, BP, glucose, lipids Monitoring & Follow-Up PSORIASIS • Efficacy (PASI, DLQI) • Side effects (hepatic, renal, infection risk) • Joint involvement

28. Comorbidities & Lifestyle PSORIASIS • Higher prevalence of metabolic syndrome , CVD , anxiety, depression • NICE recommends addressing modifiable risk factors : • Smoking cessation • Weight reduction if obese • Alcohol reduction • Exercise

29. Summary of Key Messages • Psoriasis = chronic , systemic inflammatory disease • Variety of clinical patterns → can overlap • NICE : stepped approach from topical to phototherapy to systemic • Monitor for psoriatic arthritis & comorbidities (CV, metabolic, psychological) • Holistic management improves outcomes & quality of life

30. 1. NICE Clinical Guideline CG153 – Psoriasis: assessment and management. National Institute for Health and Care Excellence (2012; last updated 2017). Available at: www.nice.org.uk/guidance/cg153 2. NICE Technology Appraisals – Various TAs on Biological Therapies for Psoriasis. E.g. TA442, TA511, TA521, TA574, etc. Available at: www.nice.org.uk/guidance/conditions-and-diseases/skin-conditions 3. British Association of Dermatologists (BAD) – Guidelines for biologic therapy for psoriasis (including regular updates). Available at: www.bad.org.uk/healthcare-professionals/clinical-standards/clinical-guidelines 4. BNF & BNF for Children – Prescribing guidance on topical and systemic therapies. Available via the NICE BNF portal at: bnf.nice.org.uk 5. Griffiths CEM, Barker JN . Pathogenesis and clinical features of psoriasis. Lancet. 2007; 370(9583): 263–271. 6. Nestle FO, Kaplan DH, Barker J . Psoriasis. N Engl J Med. 2009; 361(5): 496–509. (Seminal paper on immunopathogenesis.) 7. Smith CH, Jabbar-Lopez ZK, Yiu ZZN, et al. British Association of Dermatologists guidelines for biologic therapy for psoriasis 2020: a rapid update. Br J Dermatol. 2020; 183(4): 628–637. 8. Coates LC, Tillett W, Chandler D, et al. Psoriatic arthritis: update on pathophysiology and management. BMJ. 2023; 381: e072286. 9. BADBIR – British Association of Dermatologists Biologic Interventions Register. Available at: www.badbir.org REFERENCES

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