Psoriasis vulgaris

Psoriasis, Psori

A chronic, immune-mediated, systemic inflammatory disease characterized by clearly defined erythematous plaques with silvery-white scales, variable nail and joint involvement, and a wide range of cardiometabolic and psychosocial comorbidities.

• Global prevalence ≈ 2–3%; in Switzerland ≈ 2–3%.
• Bimodal age of onset: first peak at 15–35 years (type I) and second peak at 55–60 years (type II).
• Equal gender ratio; positive family history in 30–40% of cases with early onset.

• According to age at onset:
  • Type I (< 40 years, often HLA-C*06:02-positive, more severe).
  • Type II (> 40 years, milder, less familial).
• By morphology:
  • Psoriasis vulgaris (plaque type, > 90%).
  • Guttate, pustular (localized/generalized), erythrodermic, inverse, palmoplantar, cranioscapular, nail, psoriatic arthritis.

• Genetics: Polygenic; strongest association with HLA-C*06:02 (PSORS1, 6p21.3).
• Triggers: streptococcal pharyngitis, lithium, β-blockers, antimalarial drugs, NSAIDs, stress, alcohol, smoking, skin trauma (Köbner phenomenon).
• Immunology: Activation of the IL-23/IL-17 axis; key role for dendritic cells, Th17 cells, γδ T cells, tissue-resident memory T cells, and neutrophilic Munro microabscesses.

• Skin: Sharply defined erythematous plaques with silvery scales; scalp, extensor surfaces of elbows/knees, sacrum, genitals, palms, soles of feet.
• Nails: Pitting, onycholysis, oil drop sign.
• Joints: Psoriatic arthritis in 20–30%; dactylitis, enthesitis, axial disease.
• Signs: Köbner phenomenon, Auspitz sign, candle wax sign. Pruritus in ≈ 50%.
• Severe variants: erythroderma, generalized pustular psoriasis.

• Typical clinical picture ± family history.
• Screening: PEST questionnaire for arthritis.
• Biopsy: acanthosis, parakeratosis, loss of granular layer, Munro microabscesses, Kogoj spongiform pustules, dilated papillary capillaries.
• Laboratory: Baseline and control values for systemic therapy (complete blood count, liver values, kidney function, lipids).
• Differential diagnosis: Atopic dermatitis, seborrheic dermatitis, nummular eczema, pityriasis rubra pilaris, mycosis fungoides, secondary syphilis, tinea corporis.

• Adults: The scalp, extensor surfaces, and lumbosacral region are most commonly affected.
• Children: More common on the face and flexor surfaces.
• Medical history: Recurrent flare-ups, worsening in winter, improvement with sunlight, identifiable triggers, positive family history.

Regular psoriasiform hyperplasia with elongated retespitzen; confluent parakeratosis; absence of granular layer; neutrophils in the stratum corneum and spinous layer; dilated, tortuous papillary capillaries; perivascular lymphocytic infiltrates.

• Psoriatic arthritis (7–48%).
• Cardiovascular disease, metabolic syndrome, obesity, dyslipidemia.
• Depression/anxiety, NAFLD, IBD (Crohn's disease > ulcerative colitis), uveitis.

• Chronic recurrent course; lifelong disease.
• Early, sustained control improves quality of life and reduces the risk of comorbidities.
• Modern biologics achieve PASI 90/100 in >70% of patients.

• Avoidance of known triggers (infections, medications, alcohol, smoking, stress).
• Daily use of skin care products; weight control; regular exercise; smoking cessation.
• Screening for psoriatic arthritis and cardiometabolic diseases at every doctor's visit.

1. General measures

• Intensive patient education; psychosocial support; consistent emollient therapy.

2. Topical therapy

• First-line therapy: calcipotriol + betamethasone dipropionate foam (Enstilar®) once daily for 4–8 weeks.
• Class II–IV corticosteroids (locally adapted).
• Calcineurin inhibitors (Protopic® 0.1% ointment) for the face, flexural areas, inverse disease.

3. Phototherapy

• Narrowband UVB 311 nm (2–3 times per week) first choice; PUVA for refractory conditions or scalp conditions.

4. Systemic small molecules

• Methotrexate s.c. 10–15 mg/week + folic acid 5 mg the following day.
• Dimethyl fumarate (Skilarence®) – titrate to 240 mg twice daily; monitor lymphocytes.
• Apremilast (Otezla®) 30 mg twice daily (oral PDE-4 inhibitor).

5. Biologics

• IL-23 inhibitors:
  • Risankizumab 150 mg s.c. in weeks 0 and 4, then every 12 weeks.
  • Guselkumab 100 mg s.c. in weeks 0, 4, then every 8 weeks.
  • Tildrakizumab 100 mg s.c. in weeks 0, 4, then every 12 weeks.
• IL-17 inhibitors:
  • Secukinumab 300 mg s.c. in weeks 0, 1, 2, 3, 4, then every 4 weeks.
  • Ixekizumab 160 mg in week 0, then 80 mg every 2 weeks until week 12, then every 4 weeks.
  • Bimekizumab 320 mg every 4 weeks until week 16, then every 8 weeks.
• IL-12/23 inhibitor:
  • Ustekinumab 45 mg (< 100 kg) or 90 mg (> 100 kg) s.c. in weeks 0, 4, then every 12 weeks.
• TNF-α inhibitors:
  • Adalimumab 80 mg in week 0, then 40 mg every two weeks.
  • Certolizumab pegol 400 mg in weeks 0, 2, 4, then 200 mg every 2 weeks (safe during pregnancy).

6. Psychological measures and lifestyle changes

• Cognitive behavioral therapy, stress management programs, weight loss support.

1. Swiss Society for Dermatology and Venereology. Swiss Psoriasis Treatment Pathway. 2024.
2. Nast A, Smith C, Spuls PI, et al. EuroGuiDerm guideline on systemic treatment of psoriasis vulgaris – Part 1. J Eur Acad Dermatol Venereol. 2020;34:2461-2498. PMID: 32844529
3. Maul JT, Anzengruber F, et al. Topical therapy of psoriasis vulgaris: Swiss treatment pathway. Dermatology. 2021;237:885-894. PMID: 33756491
4. Gisondi P, Bellinato F, Girolomoni G, et al. Psoriasis and major comorbidities: systematic review and meta-analysis. JEADV. 2022;36:157-168. PMID: 34816484
5. Armstrong AW, Husted JD, et al. Risk of depression among biologics users: real-world data. JAMA Dermatol. 2023;159:223-231. PMID: 36688542
6. Federal Office of Public Health. National Strategy on Noncommunicable Diseases 2023–2029. Bern; 2023.
7. Driessen RJ, Maul JT, et al. Swiss Psoriasis Registry – initial results. Dermatology. 2024;240:112-120. PMID: 37851445
8. Schlapbach C, Yawalkar N. IL-23/IL-17 axis in Swiss practice. Ther Umsch. 2023;80:135-142. PMID: 37015678
9. European Academy of Dermatology and Venereology. EuroGuiDerm Clinical Practice Guideline – Psoriasis 2024 Update.
10. StatPearls [Internet]. Psoriasis – Etiology, Pathophysiology, Treatment. Treasure Island (FL): StatPearls Publishing; April 3, 2023. Available at: https://www.ncbi.nlm.nih.gov/books/NBK448194/