This section is from the book "A Manual Of Pathology", by Joseph Coats, Lewis K. Sutherland. Also available from Amazon: A Manual Of Pathology.
These are met with mainly as the result of chronic inflammation of the mucous membrane, and may spring from the body of the uterus or from the cervix. Sometimes there is a general irregular prominence from hypertrophy of the mucous membrane, but usually there are definite polypoid outgrowths.
The mucous polypus may consist of a limited hypertrophy of tin-mucous membrane, the tumour being a tolerably firm one unless, as sometimes happens, it becomes soft by cedema or by the excessive development of its vessels. In this latter case we may have a tumour approaching to cavernous in character. On the other hand, polypi may consist largely of Glandular structures, new-formed mucous gland-tissue constituting apparently the tissue of the tumour. These polypi are comparatively soft, and may grow to a considerable especially when they become Cystic. We have already seen that tumours consisting of glandular tissue are peculiarly apt to become cystic, and these form no exceptions. The larger polypi may somewhat distend the uterus.