Makindo Medical Notes

Related Subjects: |Nikolsky's sign |Koebner phenomenon |Psoriatic Arthritis |Psoriasis

Psoriasis is a common, chronic, relapsing-remitting inflammatory skin disease characterized by well-demarcated erythematous plaques with silvery scales. It primarily affects individuals between the ages of 10 and 30 years and is associated with significant morbidity due to its impact on quality of life and potential comorbidities.

About

• Definition: Psoriasis is a chronic autoimmune condition that accelerates the growth cycle of skin cells, leading to the formation of thick, red, scaly patches on the skin.
• Pathophysiology: Normally, skin cells mature in 21 to 28 days. In psoriasis, this process is expedited to approximately 7 days, resulting in the accumulation of skin cells and the formation of plaques.
• Onset: Typically presents between 10 to 30 years of age.
• Associated Condition: Psoriatic arthropathy, a type of inflammatory arthritis associated with psoriasis.

Aetiology

• Gender Distribution: Affects males and females equally.
• Genetic Factors: Family history and genetic susceptibility play significant roles.
• Immunological Factors: T-cell mediated inflammation without a known infectious agent.
• Pathological Changes: Increased keratinocyte proliferation and vascular growth.
• Environmental Triggers: Stress, infections, skin injuries (Koebner phenomenon), smoking, and certain medications.

Types of Psoriasis

• Chronic Plaque Psoriasis: The most common form, presenting as well-demarcated red plaques with silvery scales.
• Guttate Psoriasis: Features small, drop-like lesions, often following a streptococcal infection in children and young adults.
• Seborrheic Psoriasis: Located in seborrheic areas such as the nasolabial folds and retroauricular regions.
• Flexural (Inverse) Psoriasis: Occurs in body flexures like the axillae and under the breasts.
• Erythrodermic Psoriasis: A severe, rare form characterized by widespread redness and scaling, often requiring hospitalization.

Clinical Features

• Skin Lesions:
  • Red, scaly patches, papules, and plaques.
  • Waxy white scales that flake off.
  • Commonly found on extensor surfaces (knees, elbows), lower back, under breasts, and flexural areas (axillae).
  • Scales can be triggered by trauma (Koebner phenomenon).
  • Presence of pustules: small, sterile pustules can be localized or generalized.
  • Thick, well-demarcated scalp plaques.
  • Nail changes, including pitting and ridging.
  • Palmar-plantar pustulosis: small, deep-seated pustules on palms and soles.
  • Erythrodermic psoriasis: presents with widespread redness and requires urgent medical attention.

Differential Diagnosis

• Pityriasis rosea vs Guttate Psoriasis
• Scalp Psoriasis vs Dandruff (Seborrheic dermatitis)

Investigations

• Generally, no specific investigations are required for typical psoriasis.
• Skin biopsy may be performed in atypical cases to confirm diagnosis.

Management

• Referral:
  • Consultant dermatologist if there is diagnostic uncertainty, extensive disease, occupational disability, excessive time lost from work or school, involvement of the face, palms, or genitalia (which are difficult to treat), failure of appropriate topical treatment after two to three months, adverse reactions to topical treatments, or severe/recalcitrant disease.
  • Referral to rheumatology if signs of joint disease (e.g., swelling, dactylitis) are present.

Topical Treatments

• Simple Emollients: First-line therapy used generously (3-4 times per day). Regular use may reduce scaling and alleviate symptoms like itching. Includes creams, shampoos, and bath preparations.
• Salicylic Acid Paste: Can be applied with coal tar or dithranol to reduce scaling.
• Vitamin D Analogues: Topical agents such as calcipotriol, tacalcitol, and calcitriol are more effective than placebo and coal tar.
• Patients should have a follow-up appointment within six weeks of initiating or changing topical therapy to assess efficacy and adherence. Minimizing the number of daily treatments can improve adherence. [SIGN 122]
• Psychological Support: Address psychological issues through self-help groups and support systems. Exclude drug-induced exacerbations (e.g., beta-blockers, NSAIDs, lithium).
• Topical Corticosteroids: Including combination preparations for enhanced efficacy.
• Coal Tar Preparations: Anti-inflammatory and scaling reduction properties. Applied and then covered with emollients and bandages for thicker plaques. Note the strong odor of coal tar. A 1% coal tar solution lotion has been found moderately more effective than a 5% solution in randomized studies.
• Dithranol: Suitable for large plaques. More effective than placebo and tazarotene according to Cochrane reviews.
• Topical Retinoids: Such as tazarotene, used for mild to moderate plaque psoriasis.
• Phototherapy: Consider early referral for phototherapy in widespread guttate psoriasis not responding to topical treatments.

Specific Therapies

• Scalp Psoriasis: Short-term intermittent use of potent topical corticosteroids or a combination of potent corticosteroids and vitamin D analogues is recommended. [SIGN Guideline 121]
• Flexural Psoriasis: Use moderate potency topical corticosteroids for short-term treatment in facial and flexural areas. If ineffective, vitamin D analogues or tacrolimus ointment are recommended for intermittent use. [SIGN Guideline 121]

Systemic Treatment

• Systemic Corticosteroids: Reserved for unwell patients with widespread pustular or erythrodermic psoriasis.
• Phototherapy and Immunosuppression: For severe or refractory cases.
• Oral Retinoids: Such as acitretin, used for severe psoriasis.
• Immunosuppressants: Including mycophenolate mofetil and ciclosporin.
• Biologic Agents: Infliximab, etanercept, and efalizumab for moderate to severe cases.

Prognosis

• Psoriasis is a chronic condition with periods of remission and exacerbation.
• With appropriate treatment, symptoms can be managed effectively, and quality of life can be significantly improved.
• Early intervention can prevent complications and reduce the risk of comorbidities such as psoriatic arthritis.

References

• SIGN Guideline 121: Diagnosis and Management of Psoriasis and Psoriatic Arthritis in Adults
• World Health Organization - Psoriasis
• Medscape - Psoriasis
• Merck Manuals - Psoriasis
• American Academy of Family Physicians - Psoriasis: Diagnosis and Management