Has the additional tissue sampling been done?
There is NO conclusive diagnosis of cancer at this point. Sounds like it is still being determined what exactly it is.
I would be highly concerned, but don't "freak out" just yet.
Leiomyosarcoma is a cancer of smooth muscle cells. It appears to be a relatively rare condition. Leiomyosarcoma is a resistant cancer...not very responsive to chemotherapy or radiation. The best outcome occurs when it is taken out surgically with wide margins, early, while small and before it spreads. Folks diagnosed with this have an edge for survival if they are under the supervision of a sarcoma oncologist, or a sarcoma oncology center. They hear about new developments earlier, and will not undergo treatments of no proven benefit.
"Clinical follow-up is also recommended, particularly given the fact the uterus was morcellated." means that they carried out the hystrerectomy - morecellated means divided into pieces and removed.
It sounds like they need to do some more biopsies to see if they got all the cells that they could see.
When studying cell division in tissue samples, scientists often calculate a mitotic index, which is the ratio of dividing cells to the total number of cells in the sample. Scientists often calculate the mitotic index to compare the growth rates of different types of tissue. Cancer is higher - it divides faster (out of control). Cancer is essentially a disease where the brakes on the cell cycle have been severed.
As the number is high I suspect they'll do a follow up to see if they got it all
Hope this helps a little.