Hello, I just noticed an error on Hisoka's page where it name's Texture Surprise as a conjuration ability. First here's the description "Hisoka can apply his aura to any thin surface (such as paper or cloth) and manifests his thoughts onto it to change its appearance."
This means Texture Surprise is transmutation, he changes the "texture" of the item from one thing (ex. cloth) into another (ex. flesh, ink, paper etc.) It's not conjuration because he doesn't summon abything, he uses a regular piece of cloth like he did for his spider tattoo, and hankerchief to cover his arm, or changes his nen itself into another texture like he did to rebuild his face or change the contents of his letter.
Also he copies this technique from his master John Doe who was also a transmuter and uses a scarf to change his face