I don't fall into any of your categories.
I do believe that mental state troubles, especially long lasting ones, can manifest in psychical aspects, diseases, illnesses.
Really simplified version: distress causes a constant "flight or fight", alertness state, which slowly exhausts our "system". Other factors are also in play, from lifestyle through genetics. Nearly everything/anything can amplify or weaken the negative effects, directly or indirectly.
To answer your question, yes, it is quite possible to have a connection between your trauma and psoriasis. For example, I am more prone to muscle pains, starting at my trapezius, digestive system related disruptions, muscle spasms especially around my eye, when i face distress for a while. Nearly all the time i get a cold after the distress is lowered, nullified. I know people whose eczema worsens.
One of my instructors claimed that 95% of our psychical problems come from our (prolonged) mental troubles. I don't want to say percentages, as i said, it's way more complex... but all confirmed that there is a connection.
Might add my observation to make things even more complicated: our psychical problems can affect our mental condition too.
My studies did not go into huge depths of these topics, thus take my words with a pinch (hint?) of salt.