Psoriasis

Overview

Psoriasis is a chronic, immune-mediated inflammatory disease that primarily affects the skin, causing cells to build up rapidly on the surface. This accelerated cell production results in thick, silvery scales and red, inflamed patches that can be itchy and sometimes painful. Unlike normal skin cells that grow and shed over a month, psoriatic skin cells complete this cycle in just 3-4 days, leading to the characteristic buildup.

The condition affects approximately 125 million people worldwide, with prevalence varying by geographic region and ethnicity. Psoriasis is not contagious and cannot be spread from person to person. While it's primarily known as a skin condition, psoriasis is actually a systemic disease that can affect multiple organ systems. About 30% of people with psoriasis develop psoriatic arthritis, which causes joint pain, stiffness, and swelling.

Psoriasis typically follows a relapsing-remitting pattern, with periods of flare-ups alternating with times of remission. The severity can range from small, localized patches to complete body coverage. Beyond its physical manifestations, psoriasis significantly impacts quality of life, affecting work productivity, social interactions, and mental health. Modern understanding recognizes psoriasis as part of a broader inflammatory syndrome associated with increased risk of cardiovascular disease, metabolic syndrome, and other comorbidities.

Symptoms

Psoriasis symptoms vary considerably between individuals and can range from mild to severe. The presentation depends on the type of psoriasis and its location on the body.

Primary Skin Symptoms

Types and Their Characteristic Symptoms

Plaque Psoriasis (80-90% of cases)

• Raised, red patches with silvery scales
• Commonly on elbows, knees, scalp, and lower back
• Patches may be single or multiple
• Can cover large areas in severe cases

Guttate Psoriasis

• Small, drop-shaped lesions
• Often triggered by streptococcal infection
• Common in children and young adults
• May resolve spontaneously or become chronic

Inverse Psoriasis

• Smooth, red patches in skin folds
• Affects armpits, groin, under breasts
• Worsened by friction and sweating
• Often misdiagnosed as fungal infection

Pustular Psoriasis

• White pustules surrounded by red skin
• Can be localized or generalized
• May cause fever and chills if widespread
• Requires immediate medical attention if generalized

Erythrodermic Psoriasis

• Widespread redness covering most of body
• Severe itching and pain
• Can cause temperature regulation problems
• Medical emergency requiring hospitalization

Nail Changes

• Pitting: Small dents in nail surface
• Onycholysis: Nail separation from nail bed
• Discoloration: Yellow-brown spots under nails
• Thickening: Abnormal nail growth
• Crumbling: Brittle, easily damaged nails

Scalp Symptoms

• Thick, crusty plaques on scalp
• Extends beyond hairline onto forehead, neck, ears
• Severe dandruff-like flaking
• Temporary hair loss in affected areas
• Intense scalp itching

Joint Symptoms (Psoriatic Arthritis)

• Joint pain and stiffness
• Swollen fingers and toes (dactylitis)
• Heel pain and plantar fasciitis
• Lower back pain (spondylitis)
• Morning stiffness lasting >30 minutes

Causes

Psoriasis results from a complex interplay of genetic susceptibility, immune system dysfunction, and environmental triggers. Understanding these factors helps in managing the condition effectively.

Immune System Dysfunction

Psoriasis is fundamentally an immune-mediated disease involving:

• T-cell activation: Overactive T-lymphocytes attack healthy skin cells
• Inflammatory cascade: Release of cytokines (TNF-α, IL-17, IL-23)
• Keratinocyte proliferation: Rapid skin cell multiplication
• Angiogenesis: New blood vessel formation feeding plaques
• Neutrophil infiltration: Contributing to pustular forms

Genetic Factors

• Family history: 30-40% have affected first-degree relative
• HLA associations: HLA-Cw6 strongly linked to early-onset psoriasis
• PSORS genes: Multiple susceptibility loci identified
• IL23R and IL12B: Genes affecting immune response
• CARD14: Mutations cause familial psoriasis

Environmental Triggers

Infections

• Streptococcal throat infection (guttate psoriasis)
• HIV infection (severe psoriasis)
• Staphylococcal skin infections
• Fungal infections

Physical Triggers

• Koebner phenomenon: Psoriasis at injury sites
• Sunburn or excessive sun exposure
• Cuts, scrapes, insect bites
• Tattoos or vaccinations

Medications

• Beta-blockers (propranolol, atenolol)
• Lithium (mood stabilizer)
• Antimalarial drugs (hydroxychloroquine)
• NSAIDs (indomethacin)
• ACE inhibitors
• Corticosteroid withdrawal

Lifestyle Factors

• Stress: Major trigger for flares
• Alcohol: Excessive consumption worsens psoriasis
• Smoking: Doubles risk and increases severity
• Obesity: Adipose tissue produces inflammatory cytokines
• Cold weather: Dry conditions worsen symptoms

Hormonal Influences

• Puberty onset
• Pregnancy (may improve or worsen)
• Menopause
• Postpartum flares

Risk Factors

Multiple factors increase the likelihood of developing psoriasis or experiencing severe disease. Understanding these helps identify at-risk individuals and guide preventive strategies.

Genetic Risk Factors

• Family history:
  • One parent affected: 10% risk
  • Both parents affected: 50% risk
  • Identical twin affected: 70% risk
• Ethnicity: Higher in Caucasians, lower in Africans and Asians
• Age of onset: Bimodal peaks at 15-25 and 50-60 years

Medical Conditions

• HIV/AIDS: Paradoxically severe psoriasis despite immunosuppression
• Metabolic syndrome: Obesity, diabetes, hypertension
• Cardiovascular disease: Shared inflammatory pathways
• Inflammatory bowel disease: Crohn's disease, ulcerative colitis
• Mental health conditions: Depression, anxiety

Lifestyle Risk Factors

• Smoking:
  • Increases risk by 2-fold
  • Associated with pustular psoriasis
  • Reduces treatment effectiveness
• Alcohol consumption: Heavy drinking worsens prognosis
• Obesity: BMI >30 doubles risk
• Sedentary lifestyle: Reduces treatment response
• Poor diet: High in processed foods, low in omega-3s

Environmental Factors

• Geographic location: Higher rates in northern latitudes
• Climate: Cold, dry weather increases risk
• Occupational exposures: Chemicals, repeated trauma
• Stress levels: Chronic stress major trigger

Factors Affecting Severity

• Early age of onset (worse prognosis)
• Positive family history
• Presence of psoriatic arthritis
• Nail involvement
• Extensive body surface area affected
• Poor treatment adherence

Diagnosis

Psoriasis diagnosis is primarily clinical, based on characteristic appearance and distribution of lesions. However, various tools and tests help confirm diagnosis and assess severity.

Clinical Evaluation

History Taking

• Onset and progression of symptoms
• Family history of psoriasis or autoimmune diseases
• Previous treatments and responses
• Trigger identification
• Impact on quality of life
• Associated symptoms (joint pain, nail changes)

Physical Examination

• Lesion characteristics: Color, scaling, thickness
• Distribution pattern: Symmetrical, extensor surfaces
• Special signs:
  • Auspitz sign: Pinpoint bleeding when scale removed
  • Koebner phenomenon: Lesions at trauma sites
  • Woronoff ring: Pale halo around lesions
• Nail examination: Pitting, onycholysis
• Scalp inspection: Thick scaling, hairline involvement
• Joint assessment: Swelling, tenderness

Severity Assessment Tools

PASI (Psoriasis Area and Severity Index)

• Gold standard for clinical trials
• Scores 0-72 based on area and severity
• Mild: <10, Moderate: 10-20, Severe: >20

BSA (Body Surface Area)

• Percentage of skin affected
• 1% = area of patient's palm
• Mild: <3%, Moderate: 3-10%, Severe: >10%

DLQI (Dermatology Life Quality Index)

• 10-question survey
• Assesses impact on daily life
• Scores 0-30 (higher = worse impact)

Laboratory Tests

Usually not necessary but may include:

• Skin biopsy: For atypical presentations
  • Parakeratosis
  • Acanthosis
  • Munro microabscesses
• Blood tests:
  • ESR/CRP (inflammation markers)
  • HLA-B27 (if spondylitis suspected)
  • Rheumatoid factor (negative in psoriatic arthritis)
• Throat culture: If guttate psoriasis suspected

Differential Diagnosis

Conditions that may mimic psoriasis:

• Atopic dermatitis
• Seborrheic dermatitis
• Pityriasis rosea
• Lichen planus
• Tinea corporis (ringworm)
• Drug eruptions
• Cutaneous T-cell lymphoma

Screening for Comorbidities

• Joint examination for psoriatic arthritis
• Cardiovascular risk assessment
• Depression and anxiety screening
• Metabolic syndrome evaluation
• Liver function (if systemic therapy planned)

Treatment Options

Psoriasis treatment follows a stepwise approach based on severity, location, patient preference, and response to therapy. The goal is to achieve clear or almost clear skin while minimizing side effects.

Topical Treatments (First-line for Mild Disease)

Corticosteroids

• Potency classes: I (super potent) to VII (least potent)
• Options: Clobetasol, betamethasone, triamcinolone
• Forms: Creams, ointments, foams, shampoos
• Limitations: Skin atrophy, tachyphylaxis with prolonged use

Vitamin D Analogues

• Medications: Calcipotriene, calcitriol
• Mechanism: Normalizes skin cell production
• Advantages: No skin atrophy, good for maintenance
• Combination: Often with corticosteroids

Other Topicals

• Retinoids: Tazarotene for plaque psoriasis
• Calcineurin inhibitors: Tacrolimus for facial/intertriginous areas
• Coal tar: Traditional therapy, messy but effective
• Salicylic acid: Removes scales, enhances penetration
• Moisturizers: Essential for all patients

Phototherapy (Moderate Disease)

Narrowband UVB (NB-UVB)

• First-line phototherapy
• 2-3 times weekly
• Safe in pregnancy
• Home units available

PUVA (Psoralen + UVA)

• For thick plaques resistant to NB-UVB
• Oral or topical psoralen
• Higher skin cancer risk

Excimer Laser

• Targeted therapy for localized plaques
• 308 nm wavelength
• Fewer treatments needed

Systemic Treatments (Moderate to Severe Disease)

Traditional Systemics

• Methotrexate:
  • Weekly dosing
  • Requires folic acid supplementation
  • Monitor liver function
• Cyclosporine:
  • Rapid onset of action
  • Short-term use due to nephrotoxicity
  • Monitor blood pressure and creatinine
• Acitretin:
  • Oral retinoid
  • Good for pustular psoriasis
  • Highly teratogenic
• Apremilast:
  • PDE4 inhibitor
  • No lab monitoring required
  • GI side effects common initially

Biologic Therapies (Moderate to Severe Disease)

TNF-α Inhibitors

• Etanercept: Subcutaneous, twice weekly or weekly
• Adalimumab: Subcutaneous, every 2 weeks
• Infliximab: IV infusion, every 8 weeks
• Certolizumab: Subcutaneous, every 2 weeks

IL-17 Inhibitors

• Secukinumab: Monthly after loading
• Ixekizumab: Every 4 weeks after loading
• Brodalumab: Every 2 weeks after loading

IL-23 Inhibitors

• Guselkumab: Every 8 weeks
• Tildrakizumab: Every 12 weeks
• Risankizumab: Every 12 weeks

IL-12/23 Inhibitor

• Ustekinumab: Every 12 weeks after loading

Combination Therapy

• Topicals + phototherapy
• Topicals + systemic therapy
• Rotational therapy to minimize side effects
• Sequential therapy for rapid improvement

Lifestyle Modifications

• Weight loss: Improves treatment response
• Smoking cessation: Essential for treatment success
• Alcohol moderation: Reduces flares
• Stress management: Meditation, therapy, exercise
• Dietary changes: Anti-inflammatory diet

Prevention

While psoriasis cannot be prevented entirely due to its genetic component, many strategies can help prevent flares and reduce severity in those with the condition.

Trigger Avoidance

• Infection prevention:
  • Prompt treatment of strep throat
  • Good hygiene practices
  • Annual flu vaccination
• Skin trauma prevention:
  • Gentle skin care
  • Avoid harsh scrubbing
  • Protect from cuts and scratches
  • Use electric razors
• Medication awareness:
  • Inform doctors about psoriasis
  • Avoid triggering medications when possible
  • Never stop medications without consultation

Lifestyle Optimization

• Stress management:
  • Regular exercise
  • Meditation or yoga
  • Adequate sleep (7-9 hours)
  • Professional counseling if needed
• Healthy weight maintenance:
  • BMI <25 ideal
  • Mediterranean diet
  • Regular physical activity
• Smoking cessation:
  • Reduces severity
  • Improves treatment response
  • Decreases cardiovascular risk

Skin Care Routine

• Daily moisturizing:
  • Apply immediately after bathing
  • Use fragrance-free products
  • Thicker ointments for very dry areas
• Bathing practices:
  • Lukewarm water (not hot)
  • Short showers (5-10 minutes)
  • Add oils or oatmeal to bath
  • Pat dry, don't rub
• Sun protection:
  • Brief, controlled sun exposure may help
  • Avoid sunburn (major trigger)
  • Use mineral sunscreens

Dietary Considerations

• Anti-inflammatory foods:
  • Omega-3 fatty acids (fish, walnuts)
  • Colorful fruits and vegetables
  • Whole grains
  • Green tea
• Foods to limit:
  • Processed foods
  • Red meat
  • Refined sugars
  • Excessive alcohol

Regular Monitoring

• Keep symptom diary to identify triggers
• Regular dermatology follow-ups
• Monitor for joint symptoms
• Cardiovascular health screening
• Mental health assessment

When to See a Doctor

Timely medical consultation is crucial for proper diagnosis, treatment optimization, and prevention of complications associated with psoriasis.

Initial Consultation

See a doctor if you notice:

• Persistent red, scaly patches on skin
• Skin lesions that don't improve with moisturizers
• Family history of psoriasis with new skin changes
• Nail changes (pitting, discoloration, separation)
• Joint pain accompanying skin symptoms

Urgent Medical Attention

Seek immediate care for:

• Erythrodermic psoriasis:
  • Widespread skin redness (>75% body)
  • Severe pain and itching
  • Fever and chills
  • Dehydration
• Generalized pustular psoriasis:
  • Widespread pustules
  • High fever
  • Muscle weakness
  • Rapid pulse
• Severe infection signs:
  • Increasing pain, warmth, redness
  • Pus or foul-smelling discharge
  • Red streaks from lesions
  • Fever with infected lesions

Treatment Concerns

Contact your doctor about:

• Current treatment not improving symptoms after 6-8 weeks
• Side effects from medications
• Worsening despite treatment
• Need for stronger medications
• Interest in changing treatment approach

Monitoring and Follow-up

• New symptoms:
  • Joint pain or swelling
  • Eye inflammation
  • Mood changes
• Pregnancy planning: Medication adjustments needed
• Surgery planning: Discuss psoriasis management
• Vaccination questions: Live vaccines with biologics

Specialist Referrals

Consider seeing:

• Dermatologist: For all moderate to severe cases
• Rheumatologist: If joint symptoms present
• Mental health professional: For depression/anxiety
• Registered dietitian: For weight management
• Cardiologist: If cardiovascular risk factors

Related Conditions

Psoriasis is associated with numerous comorbidities, reflecting its systemic inflammatory nature. Understanding these connections is crucial for comprehensive care.

Autoimmune Associations

• Crohn's disease - shared genetic factors
• Ulcerative colitis - inflammatory bowel disease
• Multiple sclerosis - CNS inflammation
• Rheumatoid arthritis - joint inflammation
• Systemic lupus erythematosus

Metabolic Complications

• Type 2 diabetes: 30% increased risk
• Dyslipidemia: Abnormal cholesterol levels
• Non-alcoholic fatty liver disease: Common in psoriasis
• Chronic kidney disease: From inflammation and medications

Mental Health Impact

• Anxiety disorders
• Social phobia and isolation
• Substance abuse (alcohol, tobacco)
• Suicidal ideation (rare but serious)
• Body dysmorphic disorder

Other Associations

• Uveitis: Eye inflammation
• Osteoporosis: From chronic inflammation
• Sleep disorders: From itching and pain
• Sexual dysfunction: Physical and psychological
• Periodontal disease: Gum inflammation

References

1. Menter A, Strober BE, Kaplan DH, et al. Joint AAD-NPF guidelines of care for the management and treatment of psoriasis with biologics. J Am Acad Dermatol. 2019;80(4):1029-1072.
2. Armstrong AW, Read C. Pathophysiology, Clinical Presentation, and Treatment of Psoriasis: A Review. JAMA. 2020;323(19):1945-1960.
3. Boehncke WH, Schön MP. Psoriasis. Lancet. 2015;386(9997):983-994.
4. Elmets CA, Leonardi CL, Davis DMR, et al. Joint AAD-NPF guidelines of care for the management and treatment of psoriasis with awareness and attention to comorbidities. J Am Acad Dermatol. 2019;80(4):1073-1113.
5. Takeshita J, Grewal S, Langan SM, et al. Psoriasis and comorbid diseases: Epidemiology. J Am Acad Dermatol. 2017;76(3):377-390.