Koebner phenomenon

I remember this sign very well since I was a medical student. When I was sitting for the MRCP exam, I was told that most candidates will get psoriasis as a case in Station 5. However, not all will get a 4/4. To get 4/4 you need to shine among your other colleagues who are taking the exam at the same time.
So, remember that when you see a patient with psoriasis, always look for this sign which will be at any place with a trauma or scar.
The Koebner phenomenon, also called the isomorphic response, refers to the appearance of lesions along a site of injury.
The next question is what lesions causes Koebner phenomeonon. You need to memorise these
1) psoriasis
2) lichen planus
3) warts
4) molluscum contagiosum
5) vitiligo
There are a few more which are not so common