It develops in a small number of patients who were neglectful of treatment for syphilis or were not treated at all. 
Old and very young age, traumas (physical, psychic, medicamentous), chronic diseases and toxicosis, and alcoholism are conducive to the developm

Psoriasis is among the most widespread chronic frequently recurring diseases of the skin. According to different authors, it accounts for 3-5 to 7-10 per cent of the total number of skin diseases 
PSORIASIS – its polyeatiologic, systemic, chronic frequent

This is commonest abdominal surgery emergency
Surgical anatomy
The vermiform appendix can lie in a variety of positions. The relative frequency of the more usual positions occupied by the organ is:
retro cecal 74%
pelvic 21%
post ileal 5%