The Koebner Phenomenon can occur with people who have psoriasis.  This is a circumstance in which psoriasis lesions flare up where skin has been damaged or traumatized.  This is related to the fact that psoriasis can be triggered by other infections (especially skin irritations).

It’s not that the other diseases help psoriasis explicitly — these outbreaks are more of side-effect of the immune system becoming temporarily overworked.  In military terminology, psoriasis waits until there’s a weakness in the body’s defenses, at which point it launches an offensive that is more likely to succeed than under normal circumstances.

The Koebner Phenomenon is named after a German dermatologist from the 1800’s who discovered it.