Question:medium
Pseudoisomorphic phenomenon is seen in:
Pseudoisomorphic phenomenon is seen in:
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Pseudo-Koebner means auto-inoculation of an infectious agent along a scratch, as in viral warts.
Updated On: Jun 24, 2026
- Psoriasis
- Lichen planus
- Vitiligo
- Plane warts
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The Correct Option is D
Solution and Explanation
The key is to separate two look-alike reactions. In the real Koebner reaction, an existing inflammatory disease spreads its own typical lesions into a line of injured skin; psoriasis, lichen planus and vitiligo are the standard examples and each can throw up fresh disease lesions along a scratch. The pseudo version, called pseudo-Koebner or pseudoisomorphic, looks identical to the eye because new lesions also follow the scratch line, but the mechanism is different: a transmissible organism is physically dragged across the skin and implanted into the scratched track. Flat or plane warts fit this perfectly because they are driven by human papilloma virus, and when a patient scratches, the virus is carried along the nail line and seeds a row of new warts. The same auto-inoculation explains the linear spread of molluscum contagiosum. Since the three inflammatory choices belong to the true Koebner list and only the viral wart shows inoculation-driven linear spread, the correct fit is plane warts.\[\boxed{\text{Plane warts}}\]
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