Re: "* In Dune, Baron Harkonnen has diseases injected into his face for some reason, which gives him giant facial pustules. This was invented for the film, though both book and film versions are also morbidly obese."

The way I interpret/remember it, the injections are not diseases but treatment for the pustules, whose origin is never explained.

Either this trope needs some repairing or its description is too ambiguous.

Does this trope only apply to the hand, or does it stretch to limbs or even beyond that?