Which clinical type of psoriasis is characterized by sudden onset of widespread erythematous macules and papules, often triggered by infection or drug withdrawal, and carries risk of systemic complications?

Explanation

## Types of Psoriasis: Clinical Classification ### Guttate Psoriasis **Key Point:** Guttate psoriasis is an acute form characterized by: - **Sudden onset** of widespread **erythematous macules and papules** (1–10 mm, "raindrop-like"), distributed over the trunk and extremities - **Triggers:** Streptococcal pharyngitis (most classic), viral infections, drug withdrawal, or stress - **Systemic complications:** Generally low risk, but in severe or extensive cases, systemic involvement can occur; it may also progress to erythrodermic or pustular psoriasis in susceptible individuals - **Prognosis:** Often self-limiting, but ~30% may progress to chronic plaque psoriasis ### Comparison of Psoriasis Types | Type | Onset | Morphology | Trigger | Systemic Risk | |------|-------|-----------|---------|---------------| | **Plaque** | Insidious | Well-demarcated plaques with silvery scale | Genetic, stress | Low | | **Guttate** | Acute (days–weeks) | Small papules/macules (1–10 mm), "raindrop-like" | Streptococcal infection, drug withdrawal | Low–Moderate | | **Erythrodermic** | Acute (days) | Widespread erythema (>90% BSA), exfoliation, loss of discrete plaques | Drug withdrawal, infection, stress | **HIGH** | | **Pustular (generalized)** | Acute | Widespread pustules on erythematous base | Infection, drug withdrawal, pregnancy | **HIGH** | **High-Yield:** The stem describes **sudden onset of widespread erythematous macules and papules** — this morphology (discrete small papules/macules) is the hallmark of **guttate psoriasis**, not erythrodermic psoriasis. Erythrodermic psoriasis presents with diffuse confluent erythema and exfoliation (>90% BSA) without discrete papules. **Clinical Pearl:** Guttate psoriasis is classically triggered by **Group A beta-hemolytic Streptococcal** pharyngitis, typically appearing 2–3 weeks after the throat infection. Drug withdrawal (e.g., systemic corticosteroids) can also precipitate an acute guttate-like flare. **Distinction:** Do NOT confuse guttate psoriasis (discrete small papules/macules, acute onset) with erythrodermic psoriasis (confluent erythema >90% BSA, systemic toxicity, dermatological emergency). [cite:Harrison 21e Ch 297; Rook's Textbook of Dermatology, 9th ed.]