Endometrial biopsy states very few gray tan tissue, mostly mucus and blood. proliferative endometrium. isn't gray tissue bad? i had that previously stated on my biopsy report for a thyroid cancer?

"Grey tan tissue" is a pathologist's description of the "gross appearance" of the tissue submitted for analysis. If the endometrium is "proliferative" , the sample may include tissue from the smooth muscle of the uterus, providing the stated appearance.

Grey tan is not a meaningful finding. All tissues turn gray when fixed in formalin which is the usual process for processing a tissue for microscopic examination. Proliferative endometrium is normal endometrium. Talk to the doctor who performed the biopsy.