Endometrioid tumors are a class of tumors that arise in the
uterus
The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, f ...
or
ovaries
The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are endocr ...
that resemble
endometrial glands on histology.
They account for 80% of
endometrial carcinomas and 20% of malignant
ovarian tumors
Ovarian tumors, or ovarian neoplasms, are tumors in the ovary. Not all are ovarian cancer. They consist of mainly solid tissue, while ovarian cysts contain fluid.
In 2020, the World Health Organization (WHO) divided ovarian tumours as 90% epithel ...
.
Ovary

Ovarian endometrioid tumors are part of the
surface epithelial tumor
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
group of
ovarian neoplasms (10–20% of which are the endometrioid type).
Benign
Malignancy () is the tendency of a medical condition to become progressively worse; the term is most familiar as a characterization of cancer.
A ''malignant'' tumor contrasts with a non-cancerous benign tumor, ''benign'' tumor in that a malig ...
and borderline variants are rare, as the majority are
malignant
Malignancy () is the tendency of a medical condition to become progressively worse; the term is most familiar as a characterization of cancer.
A ''malignant'' tumor contrasts with a non-cancerous benign tumor, ''benign'' tumor in that a malig ...
.
There is an association with
endometriosis
Endometriosis is a disease in which Tissue (biology), tissue similar to the endometrium, the lining of the uterus, grows in other places in the body, outside the uterus. It occurs in women and a limited number of other female mammals. Endomet ...
and concurrent primary
endometrial carcinoma
Endometrial cancer is a cancer that arises from the endometrium (the lining of the uterus or womb). It is the result of the abnormal growth of cells that can invade or spread to other parts of the body. The first sign is most often vaginal ...
(
endometrial cancer
Endometrial cancer is a cancer that arises from the endometrium (the epithelium, lining of the uterus or womb). It is the result of the abnormal growth of cells (biology), cells that can invade or spread to other parts of the body. The first s ...
).
On gross
pathological
Pathology is the study of disease. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in the context of modern medical treatme ...
examination, the tumor is cystic and may be solid and some arise in cystic endometriosis. In 40% of cases, endometrioid tumors are found bilaterally.
Endometrium
Endometrioid carcinoma can also arise in the endometrium.
Grades 1 and 2 are considered "type 1"
endometrial cancer
Endometrial cancer is a cancer that arises from the endometrium (the epithelium, lining of the uterus or womb). It is the result of the abnormal growth of cells (biology), cells that can invade or spread to other parts of the body. The first s ...
, while grade 3 is considered "type 2".
File:Pie chart of relative incidences of endometrial carcinoma.png, Relative incidences of endometrial carcinoma
Endometrial cancer is a cancer that arises from the endometrium (the lining of the uterus or womb). It is the result of the abnormal growth of cells that can invade or spread to other parts of the body. The first sign is most often vaginal ...
s by histopathology, being endometrioid in a majority of cases
Light microscopy
Light microscopy
Microscopy is the technical field of using microscopes to view subjects too small to be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy: optical, el ...
shows tubular glands, resembling endometrium.
Molecular biology
CTNNB1 and PTEN mutations
Ovarian and endometrial endometrioid carcinomas have distinct
CTNNB1
Catenin beta-1, also known as β-catenin (''beta''-catenin), is a protein that in humans is encoded by the ''CTNNB1'' gene.
β-Catenin is a dual function protein, involved in regulation and coordination of cell–cell adhesion and gene transcr ...
and PTEN
gene mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis ...
profiles.
PTEN mutations are more frequent in low-grade endometrial endometrioid carcinomas (67%) compared with low-grade ovarian endometrioid carcinomas (17%). By contrast, CTNNB1 mutations are significantly different in low-grade ovarian endometrioid carcinomas (53%) compared with low-grade endometrial endometrioid carcinomas (28%). This difference in CTNNB1 mutation frequency may be reflective of the distinct
tumoral microenvironments; the epithelial cells lining an
endometriotic cyst within the
ovary
The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/ oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are end ...
are exposed to a highly
oxidative environment that promotes
tumorigenesis
Carcinogenesis, also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cells are transformed into cancer cells. The process is characterized by changes at the cellular, genetic, and epigenetic levels and abn ...
.
References
External links
{{DEFAULTSORT:Endometrioid Tumor
Gynaecological cancer