A 38-year-old man presents with well-demarcated erythematous plaques with silvery-white scale on his elbows, knees, and scalp for the past 2 years. He has a family history of similar skin disease in his father. Which is the most common clinical type of psoriasis in this patient?

Explanation

## Most Common Type of Psoriasis **Key Point:** Plaque psoriasis (chronic plaque psoriasis) accounts for approximately 85–90% of all psoriasis cases and is the most frequent presentation encountered in clinical practice. ### Clinical Features of Plaque Psoriasis - Well-demarcated erythematous plaques with silvery-white micaceous scale - Auspitz sign (pinpoint bleeding when scale is removed) - Koebner phenomenon (lesions appear at sites of trauma) - Predilection sites: extensor surfaces (elbows, knees), scalp, nails, genitals - Typically chronic and relapsing course - Often family history positive (as in this case) ### Comparison with Other Types | Type | Prevalence | Key Features | Trigger | |------|-----------|--------------|----------| | Plaque | 85–90% | Chronic, well-demarcated plaques | Stress, trauma, infection | | Guttate | 5–10% | Sudden onset, small papules, post-streptococcal | URTI, strep throat | | Pustular | 1–3% | Sterile pustules, systemic symptoms | Pregnancy, infection, drugs | | Erythrodermic | <3% | Generalized erythema, systemic involvement | Withdrawal of systemic steroids | **High-Yield:** The extensor surface distribution (elbows, knees) and family history are classic red flags for plaque psoriasis. **Clinical Pearl:** Plaque psoriasis is often misdiagnosed as eczema or fungal infection; however, the silvery scale, well-demarcated borders, and Auspitz sign distinguish it. **Mnemonic — Types by Frequency:** **PGPE** (Plaque >> Guttate > Pustular > Erythrodermic)