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Dermatology (Skin Conditions)

Psoriasis

A chronic, immune-mediated inflammatory disease primarily affecting the skin, characterized by well-demarcated, erythematous plaques with silvery scales. Can also affect nails and joints (psoriatic arthritis).

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Referral and warning signs

When to refer

Refer to Dermatologist/Specialist (HC4/RR) if: Diagnosis uncertain. Moderate-severe psoriasis (>10-20% BSA or significant QoL impact). Psoriasis on face, hands, feet, genitals causing distress/functional impairment. Pustular or erythrodermic psoriasis (URGENT). Suspected psoriatic arthritis. Failure to respond to topical therapy. Consideration for phototherapy or systemic treatment.

Red flags

  • Erythroderma (widespread body redness >90%).
  • Generalized pustular psoriasis (fever, malaise, widespread pustules).
  • Severe joint pain/swelling suggesting psoriatic arthritis.
  • Symptoms unresponsive to potent topical therapy.

Signs and symptoms

  • Plaque Psoriasis (Most Common):
  • - Well-demarcated, raised, red plaques.
  • - Thick, silvery-white scales.
  • - Typical sites: Extensor surfaces (elbows, knees), scalp, lower back (sacrum), umbilicus, gluteal cleft.
  • - Itching (pruritus) variable.
  • - Auspitz sign: Pinpoint bleeding when scale removed.
  • - Koebner phenomenon: New lesions appear at sites of skin trauma.
  • Other Types:
  • - Guttate Psoriasis: Small, drop-like red, scaly papules, often erupting suddenly after streptococcal infection.
  • - Inverse (Flexural) Psoriasis: Smooth, red patches in skin folds (axillae, groin, under breasts), less scaling.
  • - Pustular Psoriasis: Widespread pustules on red background, may have systemic symptoms (fever). Can be localized (palms/soles) or generalized.
  • - Erythrodermic Psoriasis: Widespread redness and scaling involving most of body surface. Serious, requires urgent management.
  • Nail Psoriasis: Pitting, onycholysis (separation from nail bed), oil drop sign (yellow discoloration), subungual hyperkeratosis, nail thickening/crumbling.
  • Psoriatic Arthritis (PsA): Inflammatory arthritis affecting peripheral joints (fingers, toes, wrists, etc.) and/or spine (spondyloarthritis), often associated with skin/nail psoriasis.

Risk factors

  • Genetic predisposition (family history common).
  • Environmental Triggers: Infections (Streptococcal throat infection for guttate), Skin trauma (Koebner), Stress, Certain medications (Beta-blockers, Lithium, Antimalarials, rapid withdrawal of systemic steroids).
  • Smoking.
  • Alcohol excess.
  • Obesity / Metabolic syndrome.

Diagnosis

Clinical assessment

Diagnosis usually based on characteristic appearance and distribution of skin lesions (well-demarcated plaques with silvery scale on extensors/scalp). Check nails and ask about joint symptoms.

Differential diagnosis

  • Eczema (Atopic/Discoid/Seborrhoeic) (usually flexural, less well-demarcated, different scale).
  • Tinea Corporis (annular, central clearing, KOH positive).
  • Lichen Planus (purple, polygonal papules, Wickham's striae).
  • Pityriasis Rosea (herald patch, 'fir tree' pattern).
  • Secondary Syphilis.
  • Cutaneous Lupus.
  • Mycosis Fungoides (Cutaneous T-cell lymphoma).

Investigations

  • Usually clinical diagnosis.
  • KOH microscopy: Rule out fungal infection.
  • Skin Biopsy: If diagnosis uncertain, shows characteristic histopathology.
  • Assess for Psoriatic Arthritis (joint pain/swelling). Check ESR/CRP, Rheumatoid Factor (usually negative).

Diagnostic criteria

Clinical diagnosis based on characteristic skin/nail findings +/- histology.

Management

Non-pharmacological management

  • Emollients: To moisturize skin and reduce scaling.
  • Stress management.
  • Avoid known triggers (trauma, certain drugs).
  • Smoking cessation, moderate alcohol.
  • Weight management.
  • Sunlight/UV exposure (in moderation can help, but avoid sunburn).

Pharmacological treatment

  • Treatment depends on severity (BSA%), location, type, impact on QoL. Requires stepwise approach, often specialist input.
  • Topical Therapy (Mild-Moderate Psoriasis <10-20% BSA):
  • - Topical Corticosteroids: Various potencies used depending on site/severity. Potent steroids (e.g., Betamethasone, Clobetasol) often needed for thick plaques (apply OD/BID for limited periods, taper). Use lower potency on face/flexures. (LOC: HC2-Betamethasone, HC4/RR-Potent)
  • - Vitamin D Analogues (e.g., Calcipotriol/Calcipotriene, Calcitriol): Effective, often used in combination with steroids. Slower onset than steroids, less skin thinning risk. Apply OD/BID. (LOC: Specialist)
  • - Coal Tar Preparations: Ointments, shampoos. Effective but messy/staining. (LOC: HC4/Specialist)
  • - Salicylic Acid: Keratolytic, helps remove thick scale (often combined with steroids/tar).
  • - Topical Retinoids (Tazarotene): Especially for plaque psoriasis. Irritating. Avoid in pregnancy.
  • - Topical Calcineurin Inhibitors (Tacrolimus/Pimecrolimus): Off-label for face/flexures.
  • Phototherapy (Moderate-Severe Psoriasis):
  • - Narrowband UVB (NB-UVB): Most common. Requires specialized unit. (LOC: Specialist/RR)
  • - Broadband UVB.
  • - PUVA (Psoralen + UVA): Highly effective but more side effects/cancer risk.
  • Systemic Therapy (Moderate-Severe / Refractory / PsA): (Specialist Management Only)
  • - Conventional Systemics: Methotrexate, Ciclosporin, Acitretin (oral retinoid - teratogenic). Require careful monitoring.
  • - Biologic Agents: Target specific immune pathways (TNF-alpha inhibitors - Etanercept, Adalimumab; IL-17 inhibitors - Secukinumab, Ixekizumab; IL-23 inhibitors - Ustekinumab, Guselkumab, etc.). Very effective but expensive, require screening, risk of infection.
  • Psoriatic Arthritis: Requires collaboration with Rheumatologist. NSAIDs, DMARDs (Methotrexate, Leflunomide), Biologics used.

Monitoring

Monitor treatment efficacy and side effects. Assess BSA involvement, PASI score (specialist). Monitor for psoriatic arthritis symptoms. Regular checks if on systemic therapy (bloods, BP etc).

Complications

  • Psoriatic Arthritis.
  • Psychosocial impact (low self-esteem, depression, stigma).
  • Increased risk of cardiovascular disease and metabolic syndrome.
  • Erythroderma.
  • Pustular psoriasis complications.
  • Secondary infection.
  • Side effects of treatments.

Prevention

  • Cannot prevent onset, but can manage triggers to reduce flares.
  • Healthy lifestyle may mitigate cardiovascular risk.

Patient education

  • Explanation of psoriasis as a chronic immune condition (not contagious).
  • Chronic nature with flares and remissions.
  • Identifying and managing triggers.
  • Correct use of topical treatments (steroids, Vit D analogues, emollients).
  • Potential side effects of treatments.
  • Lifestyle advice (smoking, alcohol, weight).
  • Importance of regular follow-up.
  • Recognizing signs of psoriatic arthritis.
  • Support groups/resources.

Uganda-specific notes

Psoriasis occurs but may be underdiagnosed. Topical steroids (Betamethasone) and Coal Tar are mainstays where available. Access to Vitamin D analogues, phototherapy, and systemic/biologic agents extremely limited. Need to differentiate from fungal infections.

References

  • Uganda Clinical Guidelines (UCG) 2023

    Chapter 22, Section 22.5.4

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