Compensatory hypertrophy is a different, temporary growth response in which residual tissue increases in mass and cell number: cells undergo mitosis but do not dedifferentiate.
If it is a fibromatous tumor, you need to check mitosis and cytologic atypia carefully to see if it is malignant, like fibrothecoma.Malignant fibrous tumor is very few in ovary.
After all, red blood cells have to come from somewhere, and cells do need mitochondria and a nucleus with DNA to go through mitosis, make new cells, and make all of that hemoglobin protein.