Experimental Koebner phenomenon in patients with psoriasis.

Area of Science:

• Dermatology
• Immunology
• Skin Diseases

Background:

• The Koebner phenomenon describes psoriasis development at sites of skin trauma.
• The 'all-or-none' principle suggests a uniform response across all injured areas or none at all.

Purpose of the Study:

• To assess patient concordance with the 'all-or-none' principle of the Koebner phenomenon.
• To investigate Koebner response variability using a standardized trauma method.

Main Methods:

• Sixty-two psoriasis patients underwent standardized skin pricking on their forearms.
• Psoriatic plaque development was assessed at 14 and 28 days post-trauma.

Main Results:

• A negative Koebner response (no lesions) occurred in 72.5% of patients.
• One patient (1.6%) showed a positive response in all 10 sites.
• 25.8% of patients displayed a partial Koebner response (1-9 lesions).

Conclusions:

• Standardized skin trauma can induce Koebner responses in psoriasis patients.
• The 'all-or-none' principle is not consistently observed in the Koebner phenomenon.