What is the best approach to managing various skin conditions, including acne, eczema, and psoriasis, considering proper diagnosis, treatment, and potential complications in patients?

Managing Common Dermatologic Conditions: Acne, Eczema, and Psoriasis

Psoriasis Management

For mild-to-moderate chronic plaque psoriasis, initiate treatment with high-potency topical corticosteroids (clobetasol propionate 0.05% or betamethasone dipropionate 0.05%) combined with calcipotriol, applied twice daily for 2-4 weeks maximum, achieving superior efficacy compared to either agent alone. 1, 2, 3

Initial Assessment and Severity Stratification

• Diagnosis is clinical based on characteristic erythematous, scaly plaques in typical distributions; laboratory investigations are rarely helpful and should not delay treatment 4, 1
• Assess severity using two components: the patient's perception of disability ("need for treatment") and objective body surface area involvement using body mapping or PASI scoring 4, 1
• Screen for exacerbating medications including alcohol, beta-blockers, NSAIDs, lithium, chloroquine, and mepacrine—the latter three can cause severe, potentially fatal psoriasis deterioration 4, 1, 2

Topical Therapy Algorithm for Mild-to-Moderate Disease (BSA <5%)

First-line approach:

• Apply clobetasol propionate 0.05% or betamethasone dipropionate 0.05% twice daily to thick plaques for maximum 2-4 weeks to prevent skin atrophy, striae, and systemic absorption 1, 2, 3
• Combine with calcipotriol (vitamin D analog) for synergistic effect superior to either agent alone, reducing long-term corticosteroid exposure 1, 2, 3
• Maximum quantity of ultra-high potency corticosteroids should not exceed 50g per week 2

Critical monitoring requirements:

• Clinical review every 4 weeks during active treatment to assess response and monitor for adverse effects 2
• No unsupervised repeat prescriptions of high-potency corticosteroids 4, 2
• No more than 100g of moderately potent (BNF grade III) preparation should be applied each month 4
• Implement periods each year when alternative treatments are employed to prevent tachyphylaxis 3

Second-line topical options when first-line fails:

• Add tazarotene with moderate-to-high potency corticosteroids for body plaques to reduce irritation while enhancing efficacy 1, 3
• Coal tar preparations (extremely safe and cost-effective): start with 0.5-1.0% crude coal tar in petroleum jelly and increase concentration every few days to maximum 10% as tolerated 4, 2, 3
• Dithranol (anthralin): start at 0.1-0.25% concentration and increase in doubling concentrations as tolerated; use short contact mode (15-45 minutes every 24 hours) to minimize irritancy and staining 4, 2, 3

Important caveat: Patients failing one topical agent may respond to another due to poorly understood individual variation—trial alternative topical agents before escalating to systemic therapy 4, 1, 3

Systemic Therapy for Moderate-to-Severe Disease (BSA ≥5%)

Indications for systemic treatment:

• Disease affects ≥5% body surface area despite adequate topical therapy 2, 3
• Ultra-high potency corticosteroids fail after 2-4 weeks of appropriate use 2
• Repeated hospital admissions for topical treatment 4
• Extensive chronic plaque psoriasis in elderly or infirm patients 4, 3
• Generalized pustular or erythrodermic psoriasis 4
• Severe psoriatic arthropathy 4, 3

First-line systemic treatment:

• Photochemotherapy (PUVA) is the least toxic systemic agent and should be considered first-choice systemic treatment 4, 1, 3
• Start at 70% of minimum phototoxic dose (read at 72 hours), increasing successive doses by 40% of preceding dose if no erythema develops 4, 1, 3
• Response expected within 4 weeks 4, 1
• Contraindications include pregnancy, clinically significant cataracts, age <18, previous cutaneous malignancy, and previous ionizing radiation 4
• Requires ultraviolet A eye protection and shielding of genitalia unless specific need to treat 4

Conventional systemic agents (second-line):

• Methotrexate (most cost-effective systemic option): response time 2 weeks; absolute contraindications include pregnancy, breastfeeding, wish to father children, significant hepatic damage, anemia, leucopenia, thrombocytopenia 4, 2, 3
• Cyclosporin: response time 3 weeks; requires blood pressure and serum creatinine monitoring every 2 weeks for first 3 months, then monthly 4, 5
  • Reduce dose by 25-50% if serum creatinine rises ≥25% above baseline 5
  • Discontinue if creatinine rises ≥50% above baseline or if reversibility not achievable after two dosage modifications 5
  • Maximum dose should not exceed 4 mg/kg/day to reduce nephropathy risk 5
  • Contraindicated in pregnancy, abnormal renal function, uncontrolled hypertension, and previous/concomitant malignancy 4, 5
• Etretinate: response time 6 weeks; requires contraception for 2 years after stopping treatment 4

Biologic therapy (third-line):

• Adalimumab (TNF-α inhibitor) for moderate-to-severe chronic plaque psoriasis when other systemic therapies are medically less appropriate, achieving treatment goals in 68.2-79.3% of patients by week 16 1, 3
• For generalized pustular psoriasis, infliximab demonstrates rapid and often complete disease clearance and should be considered first-line biologic therapy at 5 mg/kg infused at weeks 0,2, and 6, then every 8 weeks thereafter 3
• Screen for active or latent tuberculosis, hepatitis B, and fungal infections before initiating biologics 3

Critical Medications to Absolutely Avoid

• Never prescribe systemic corticosteroids for psoriasis—they precipitate erythrodermic psoriasis, generalized pustular psoriasis, or very unstable disease upon discontinuation 1, 2, 3
• Avoid lithium, chloroquine, and mepacrine—associated with severe, potentially fatal psoriasis deterioration 4, 1, 2
• Potassium-sparing diuretics should not be used as cyclosporine may cause hyperkalemia 5
• Do not combine salicylic acid with calcipotriene—it inactivates the vitamin D analog 2

Common Pitfalls to Avoid

• Perceived "tachyphylaxis" to topical corticosteroids is usually poor patient adherence, not true receptor down-regulation—address compliance issues before switching therapies 1, 3
• Patients should not be treated concurrently with cyclosporine and PUVA, UVB, other radiation therapy, or other immunosuppressive agents due to excessive immunosuppression risk and subsequent malignancy risk 5
• Skin lesions not typical for psoriasis should be biopsied before starting cyclosporine—patients with malignant or premalignant skin changes should only be treated after appropriate treatment of such lesions and if no other treatment option exists 5
• Increased risk for skin and lymphoproliferative malignancies in cyclosporine-treated psoriasis patients—tumors reported in 2.2% of patients, with skin malignancies in 1.1% 5

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Acne and Eczema Management

The provided evidence focuses predominantly on psoriasis management. For acne and eczema, general dermatologic principles apply: acne is the number one reason for dermatologic consultations worldwide with increasing prevalence in adolescents and females 6, while atopic dermatitis is an inflammatory disease with highest prevalence in children and adolescents 6. Complementary and alternative medicine use is common in these conditions, with patients valuing natural approaches and perceived lesser potential for adverse effects 7. However, specific evidence-based treatment algorithms for acne and eczema are not provided in the available guidelines and should be sought from dedicated acne and eczema management guidelines.