Regarding the clinical classification and subtypes of psoriasis, all of the following statements are correct EXCEPT:

Question

Accepted Answer

B. Erythrodermic psoriasis represents an exfoliative form that covers >90% of body surface area and is triggered exclusively by withdrawal of systemic corticosteroids. ## Classification of Psoriasis Subtypes

**Key Point:** Erythrodermic psoriasis can be triggered by multiple factors, NOT exclusively by corticosteroid withdrawal. Common triggers include infections, drugs, irritants, and stress.

### Psoriasis Subtypes: Comparison Table

| Subtype | Prevalence | Key Features | Triggers/Associations |
|---------|-----------|--------------|----------------------|
| **Plaque psoriasis** | 80–90% | Well-demarcated plaques with silvery scale; elbows, knees, scalp | Genetic predisposition, stress, infection |
| **Guttate psoriasis** | 5–10% | Widespread small papules ("raindrop" appearance) | Streptococcal pharyngitis (2–3 weeks prior); can resolve spontaneously |
| **Pustular psoriasis (generalized)** | 1–3% | Sterile pustules on erythematous base; systemic symptoms (fever, malaise, arthralgia) | Withdrawal of systemic corticosteroids, pregnancy, infections |
| **Erythrodermic psoriasis** | <3% | Exfoliative, >90% BSA involvement; systemic symptoms (fever, chills, dehydration) | Corticosteroid withdrawal, infections, drugs, irritants, stress, poor disease control |

**High-Yield:** Erythrodermic psoriasis is a **medical emergency** requiring hospitalization for fluid/electrolyte management and thermoregulation. It is NOT caused exclusively by corticosteroid withdrawal — multiple triggers exist.

### Why Corticosteroid Withdrawal is Incomplete

While abrupt withdrawal of systemic corticosteroids is a well-known trigger for erythrodermic and pustular psoriasis, it is **not the only trigger**. Other causes include:
- Infections (bacterial, viral)
- Medications (NSAIDs, lithium, beta-blockers)
- Irritants and allergens
- Psychological stress
- Poor disease control

**Clinical Pearl:** Patients on systemic corticosteroids for psoriasis should be tapered slowly and transitioned to steroid-sparing agents (topical agents, biologics) to prevent rebound flares or conversion to erythrodermic/pustular forms.

**Mnemonic:** **PIGE** for psoriasis subtypes — **P**laque (most common), **I**nverse, **G**uttate, **E**rythrodermic/Exfoliative (and Pustular).

[cite:Robbins 10e Ch 25; Park 26e Ch 33]

Answer

A. Pustular psoriasis (generalized type) is characterized by widespread erythema with sterile pustules and typically presents with systemic symptoms including fever and malaise

Answer

C. Guttate psoriasis typically follows a streptococcal pharyngitis infection by 2–3 weeks and presents with widespread small papules

Answer

D. Plaque psoriasis is the most common form, accounting for approximately 80–90% of all psoriasis cases

Regarding the clinical classification and subtypes of psoriasis, all of the following statements are correct EXCEPT:

Explanation

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