Section Editor: Kianoosh Keyhanian MD FRCPC
May 24, 2026
The uterus is the hollow, muscular organ where a pregnancy develops. Its inner lining is called the endometrium, and the thick muscular wall around it is called the myometrium. The endometrium changes throughout the menstrual cycle, so a biopsy or hysterectomy can show many different patterns. When tissue is removed from the uterus, a pathologist examines it under a microscope and describes what they see in your pathology report.
This page brings together our guides to conditions found in the uterus and endometrium. The articles are grouped by type to help you find the one that matches your diagnosis. Select any article below to learn more.
Cancers of the uterus
These diagnoses are cancers that develop in the uterus. Some start in the endometrium (the lining) and others start in the muscle or supporting tissue of the uterine wall. The articles explain how each type is diagnosed and what the details in your pathology report mean.
Endometrial endometrioid carcinoma
Endometrial endometrioid carcinoma is the most common type of cancer of the uterus. It develops from the cells of the endometrium, the lining of the uterus. This article explains how it is diagnosed and what the details in your pathology report mean.
You may find this helpful if your report mentions endometrioid carcinoma of the endometrium, the most common type of uterine cancer.
Endometrial serous carcinoma is a type of uterine cancer that tends to grow more quickly than the endometrioid type. This article explains how it is diagnosed and what your report describes.
You may find this helpful if your report mentions serous carcinoma of the endometrium.
Uterine serous carcinoma is another name for endometrial serous carcinoma, a type of uterine cancer that tends to grow more quickly than the endometrioid type. This article explains what this diagnosis means.
You may find this helpful if your report mentions uterine serous carcinoma.
Endometrial clear cell carcinoma
Endometrial clear cell carcinoma is an uncommon type of uterine cancer. This article explains how it is diagnosed and what your pathology report describes.
You may find this helpful if your report mentions clear cell carcinoma of the endometrium.
Carcinosarcoma is a uterine cancer that contains a mix of two different cancer types. It tends to grow quickly. This article explains what this diagnosis means.
You may find this helpful if your report mentions carcinosarcoma of the uterus.
Dedifferentiated carcinoma is a uterine cancer made up of two parts: one that resembles a recognizable cancer type and one that does not. This article explains what this diagnosis means.
You may find this helpful if your report mentions dedifferentiated carcinoma of the endometrium.
Undifferentiated carcinoma is a fast-growing uterine cancer in which the cells look very abnormal and do not resemble a specific type. This article explains what this diagnosis means.
You may find this helpful if your report mentions undifferentiated carcinoma of the endometrium.
Leiomyosarcoma is a cancer that develops from the smooth muscle of the uterine wall. This article explains how it is diagnosed and what your pathology report describes.
You may find this helpful if your report mentions leiomyosarcoma of the uterus.
Low grade endometrial stromal sarcoma
Low grade endometrial stromal sarcoma is a slow-growing cancer that develops from the supporting tissue of the endometrium. This article explains what this diagnosis means.
You may find this helpful if your report mentions low grade endometrial stromal sarcoma.
High grade endometrial stromal sarcoma
High grade endometrial stromal sarcoma is a faster-growing cancer that develops from the supporting tissue of the endometrium. This article explains what this diagnosis means.
You may find this helpful if your report mentions high grade endometrial stromal sarcoma.
Tumors of uncertain potential
This diagnosis describes a tumor that cannot be clearly classified as noncancerous or cancerous. It is not a cancer diagnosis, but its behavior cannot be fully predicted, so it is followed closely. The article explains what this diagnosis means.
Smooth muscle tumor of uncertain malignant potential
This diagnosis is used for a smooth muscle tumor of the uterus that has some unusual features but not enough to be called a cancer. It is not diagnosed as cancer, but its behavior cannot be fully predicted. This article explains what this diagnosis means.
You may find this helpful if your report mentions a smooth muscle tumor of uncertain malignant potential, or STUMP.
Precancerous changes
These diagnoses describe precancerous changes in the lining of the uterus. They are not cancer, but they increase the risk that endometrial cancer develops over time. The articles explain what each diagnosis means.
Atypical endometrial hyperplasia
Atypical endometrial hyperplasia is a precancerous change in which the lining of the uterus becomes thickened and the cells look abnormal. It is not cancer, but it carries a meaningful risk of developing into cancer. This article explains what this diagnosis means.
You may find this helpful if your report mentions atypical endometrial hyperplasia, also called endometrioid intraepithelial neoplasia or EIN.
Endometrioid intraepithelial neoplasia
Endometrioid intraepithelial neoplasia, or EIN, is another name for atypical endometrial hyperplasia, a precancerous change in the lining of the uterus. This article explains what this diagnosis means.
You may find this helpful if your report mentions endometrioid intraepithelial neoplasia or EIN.
Noncancerous tumors and growths
These diagnoses are noncancerous tumors and growths of the uterus. They do not spread to other parts of the body, although they are often removed because of symptoms such as bleeding. The articles explain what each diagnosis means.
A leiomyoma, commonly called a fibroid, is a very common, noncancerous tumor of the smooth muscle of the uterus. This article explains what this diagnosis means and how it is treated.
You may find this helpful if your report mentions a leiomyoma or fibroid of the uterus.
A cellular leiomyoma is a noncancerous uterine fibroid in which the cells are packed more closely together than in a typical fibroid. This article explains what this diagnosis means.
You may find this helpful if your report mentions a cellular leiomyoma of the uterus.
A mitotically active leiomyoma is a noncancerous uterine fibroid in which the cells are dividing more than usual. Despite this, it behaves like an ordinary fibroid. This article explains what this diagnosis means.
You may find this helpful if your report mentions a mitotically active leiomyoma of the uterus.
An endometrial polyp is a common, noncancerous growth of the lining of the uterus. This article explains what this diagnosis means and how it is treated.
You may find this helpful if your report mentions an endometrial polyp.
Noncancerous changes of the endometrium
These diagnoses describe the state of the endometrium, the lining of the uterus. They are not cancer. Many are normal findings that reflect where you are in the menstrual cycle or in life. The articles explain what each diagnosis means.
Proliferative endometrium is a normal finding that describes the lining of the uterus during the first part of the menstrual cycle. This article explains what this diagnosis means.
You may find this helpful if your report mentions proliferative endometrium.
Secretory endometrium is a normal finding that describes the lining of the uterus during the second part of the menstrual cycle, after an egg is released. This article explains what this diagnosis means.
You may find this helpful if your report mentions secretory endometrium.
Atrophic endometrium is a thin, inactive lining of the uterus. It is a normal finding after menopause. This article explains what this diagnosis means.
You may find this helpful if your report mentions atrophic endometrium.
Inactive endometrium describes a lining of the uterus that is not being stimulated by hormones. It is a common, noncancerous finding. This article explains what this diagnosis means.
You may find this helpful if your report mentions inactive endometrium.
Disordered proliferative endometrium
Disordered proliferative endometrium is a noncancerous change caused by an imbalance of hormones. It is not cancer and is not precancerous. This article explains what this diagnosis means.
You may find this helpful if your report mentions disordered proliferative endometrium.
Endometrial hyperplasia without atypia
Endometrial hyperplasia without atypia is a noncancerous overgrowth of the lining of the uterus, usually caused by hormones. It carries only a small risk of developing into cancer. This article explains what this diagnosis means.
You may find this helpful if your report mentions endometrial hyperplasia without atypia, or simple or complex hyperplasia.
Other noncancerous conditions
These diagnoses are other noncancerous conditions of the uterus. They are not cancer. The articles explain what each diagnosis means and what a pathologist looks for.
Adenomyosis is a common, noncancerous condition in which tissue similar to the lining of the uterus is found within the muscular wall. This article explains what this diagnosis means.
You may find this helpful if your report mentions adenomyosis.
Endometriosis is a common, noncancerous condition in which tissue similar to the lining of the uterus grows outside the uterus. This article explains what this diagnosis means and what a pathologist looks for.
You may find this helpful if your report mentions endometriosis.
Chronic endometritis is long-lasting inflammation of the lining of the uterus. It is not cancer. This article explains what this diagnosis means and what a pathologist looks for.
You may find this helpful if your report mentions chronic endometritis.
Products of conception is the term pathologists use for tissue from a pregnancy. This article explains what a pathologist looks for when examining this tissue and what the findings can mean.
You may find this helpful if your report mentions products of conception.
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