Based on the description, they certainly could be tapeworm cysts - I've commonly found them within the muscle of mule deer. They could also be sarcocysts, though usually those are microscopic or just barely visible in deer and elk (they can get very large in waterfowl, commonly called "duck rice breast disease" due to the appearance like grains of white rice in the breast meat. Both are harmless when cooked, and sarcocysts (caused by a protozoan) are harmless regardless. Anyone who has ever eaten elk has eaten sarcocystis, they are ubiquitous in elk - every one has them. They are microscopic typically except in heart muscle, where they are just barely visible to the eye.
Abundance of worm cysts seems to be variable by year, in my experience. Some years I get several calls from concerned hunters, other years none. Three years ago in WY all three mule deer we shot had numerous larval worm cysts in the meat. I've found a couple in each WA mule deer I've killed the past 2 years.
So, they won't make you sick, but if they gross you out - don't eat it. I answer the "is it safe" question with yes, but I also don't tell anyone they have to eat something that turns them off. It's worth seeing if someone else wants it, if you don't - just tell them what and why. Prior to the routine application of antibiotics to livestock, people were much more used to parasites. I've heard older rural people who grew up on game and/or slaughtered their own unmedicated livestock, for whom parasites were a fact of life, laugh at the thought of someone throwing away "wormy" meat - and gratefully taking it as they were too infirm to hunt any longer, and retired on a fixed income.
I have no qualms cutting out a few worm cysts while processing my game. I did toss the mallard with rice breast I shot several years ago, even though I know it is perfectly harmless - simply because I had no desire to eat that gross thing!
