A 38-year-old man presents with a 6-month history of erythematous, well-demarcated plaques with silvery scale over his elbows, knees, and scalp. Auspitz sign is positive. He denies systemic symptoms. Serology for HIV and streptococcal infection is negative. What is the most appropriate next step in management?

Explanation

## Clinical Diagnosis and Management Strategy **Key Point:** This patient has classic plaque psoriasis (chronic, localized, well-demarcated lesions with positive Auspitz sign). The diagnosis is clinical and does not require histopathology confirmation in straightforward cases. ### Rationale for Correct Answer For mild-to-moderate localized plaque psoriasis without systemic involvement: 1. **Topical therapy is first-line** — Potent topical corticosteroids (Class II–III) combined with emollients are the standard initial approach for limited body surface area involvement. 2. **Counseling on triggers** — Stress, infection, trauma, and certain drugs (lithium, NSAIDs, beta-blockers) are known precipitants; patient education reduces relapse risk. 3. **No systemic features** — Absence of arthralgia, nail involvement, or extensive disease does not warrant systemic agents or specialist referral at this stage. ### Management Algorithm for Plaque Psoriasis ```mermaid flowchart TD A[Plaque psoriasis diagnosed clinically]:::outcome --> B{Body Surface Area affected?}:::decision B -->|< 10% BSA| C[Topical corticosteroids + emollients]:::action B -->|10-30% BSA| D[Topical therapy ± phototherapy]:::action B -->|> 30% BSA or systemic features| E[Consider systemic agents]:::action C --> F[Counsel on triggers & lifestyle]:::action D --> F E --> G[Methotrexate, acitretin, or biologics]:::action F --> H[Review at 4-6 weeks]:::action ``` **High-Yield:** Plaque psoriasis is a **clinical diagnosis**; biopsy is reserved for atypical presentations or diagnostic uncertainty, not routine cases. **Clinical Pearl:** Auspitz sign (pinpoint bleeding after gentle scale removal) and Koebner phenomenon (lesions at sites of trauma) are hallmark features that support the diagnosis without need for biopsy. ## Why Topical Therapy Works Here | Feature | Implication | |---------|-------------| | Localized lesions (elbows, knees, scalp) | Topical agents penetrate well; systemic therapy unnecessary | | No arthralgia or nail dystrophy | No evidence of systemic/arthritic disease | | 6-month duration | Chronic plaque type; not acute pustular or erythrodermic | | Negative serology | Rules out secondary causes; primary psoriasis confirmed |