Yikes! Is that raised, gray area part of the plant, or is it some kind of growth on top of the plant -- like a fungus? Is it soft and oozing?

The yellow exudate is sort of waxy, but hard and brittle. The gray areas are dried out, dead areas of the plant's skin. I think there may be some sort of larva under the skin feeding on the plant but couldn't find any when I cut out a piece. Here are some more pictures:

Here's a wider view of the most affected part of the plant showing the worst section on the left.

A closer look at the part on the right with many lesions or scales or whatever they are. If you look closely you can see concentric rings in the middle of each lesion. I expected to find a larva of some kind in one of these but didn't see anything when I cut one open. The tissue just under the "scale" is healthy.

And here is a flower. :) The plant seems to not be harmed at all by this but it's unsightly where the lesions are.

Looks like fungus, maybe Prickly Pear leaf spot (dry rot) caused by Phyllostica fungus

It could be that Alain, i'm searching for examples and not finding any that look like mine but the description seems similar

Does this fungus spread to other plants or is it common to cacti?