Endometrial pathology
The endometrium is a mucosa composed of:
- epithelium: glandular structures lined by columnar cells
o proliferative phase: initially small glands with numerous mitotic figures,
then large, convoluted glands and lining of cells with basal nuclei and
apical cytoplasm.
o secretory phase: nuclei displaced to the center of the cell, mucus
accumulates at the basal pole and migrates apically to the secretory pole.
o menstrual phase: epithelium detaches from the stroma → bleeding
- stroma: mesenchymal tissue characterized by very high cellularity. Disintegration
occurs in the menstrual phase of the cycle
The endometrium is responsive to sex hormones and undergoes changes (also following
the ovarian cycle) during the menstrual cycle: the first 14-16 days we have a proliferative
phase, identifiable histologically by the presence of multiple mitotic figures, and after
ovulation there is a secretory phase, terminating in a menstrual phase or
desquamation when estrogen and progesterone levels lower.
Endometriosis and adenomyosis
Endometriosis is the ectopic
displacement of the endometrial
mucosa outside the lining of the
uterine cavity; it may affect every
part of the abdominal cavity and
even spread distally e.g. to the
lungs. It commonly occurs in
women aged 25-40 and causes
may be retrograde menstruation,
metastatic spread, coelomic
metaplasia and altered immunity.
Risk factors are prolonged
menstrual flow, early menarche,
delayed child-bearing and
immune disorders. Diagnosis is by
laparoscopy and biopsy; there is
no known cure and eventually
there may be secondary infertility
due to scarring of the pelvis and
abdomen so that the normal anatomy is modified.
- Adenomyosis is a form of endometriosis limited to the uterine wall. Clinical
signs include a bloated and enlarged uterus. Risk factors include high parity and
uterine surgery. Usually occurs in women aged 35 or older. Hysterectomies are
diagnostic and curative. Histologically it is characterized by cystically dilated
, endometrial glands on the uterine wall and positive staining for hemosiderin
(Pearls Prussian blue) underneath the cysts due to digestion of blood.
Whilst both conditions may be asymptomatic, they are usually characterized by chronic
pelvic pain, poorly responsive to NSAIDs, dysmenorrhea, dyspareunia and reduced
fertility. Both are estrogen-dependent diseases that have multifactorial etiologies.
Clinical manifestations
- Endometriosis in the recto-uterine Douglas pouch may lead to vaginal bleeding
due to response to estrogen exposure and progressive fibrosis
- In the ovary, endometriotic foci take the form of ‘chocolate cysts’ that may rupture
due to increased pressure from the bloody content causing peritonitic pain; there
is chronic progression to fibrosis. This is the only location where endometriosis
may lead to ovarian cancer, because of the peculiar pro-proliferative
microenvironment rich in cytokines and growth factors.
- In the intestinal wall, endometriosis may lead to obstruction. Notice that
histologically, endometriosis in the intestine may resemble an adenocarcinoma
however we can differentiate between the two entities because endometriosis
involves the transposition of the entire mucosa and not only the epithelial part of
the gland; to confirm, we can use CD10 stain (positive in the presence of stromal
cells).
- In the cervix, endometriosis is visible upon observation of a highly cellular stroma
surrounding glands with overlying squamous epithelium of the ectocervix. HPV in
those areas is negative so it is not an adenocarcinoma
- In the lungs, endometriotic foci may bleed
Abnormal uterine bleeding (AUB)
Endometrial cancers are often detected
early because they manifest with abnormal
uterine bleeding, defined as bleeding from
the uterine corpus that is abnormal in
volume, regularity and/or timing that has
been present for the majority of the last 6
months. Bleeding outside the fertile period
and especially in the perimenopausal and
postmenopausal period should raise
suspicion for organic lesions → these
patients should undergo
US examinations and
gynecological visits;
upon detection of a
thickened endometrium,
these patients should
perform hysteroscopy
with biopsy.
Causes of AUB may be
benign, like polyps and
The endometrium is a mucosa composed of:
- epithelium: glandular structures lined by columnar cells
o proliferative phase: initially small glands with numerous mitotic figures,
then large, convoluted glands and lining of cells with basal nuclei and
apical cytoplasm.
o secretory phase: nuclei displaced to the center of the cell, mucus
accumulates at the basal pole and migrates apically to the secretory pole.
o menstrual phase: epithelium detaches from the stroma → bleeding
- stroma: mesenchymal tissue characterized by very high cellularity. Disintegration
occurs in the menstrual phase of the cycle
The endometrium is responsive to sex hormones and undergoes changes (also following
the ovarian cycle) during the menstrual cycle: the first 14-16 days we have a proliferative
phase, identifiable histologically by the presence of multiple mitotic figures, and after
ovulation there is a secretory phase, terminating in a menstrual phase or
desquamation when estrogen and progesterone levels lower.
Endometriosis and adenomyosis
Endometriosis is the ectopic
displacement of the endometrial
mucosa outside the lining of the
uterine cavity; it may affect every
part of the abdominal cavity and
even spread distally e.g. to the
lungs. It commonly occurs in
women aged 25-40 and causes
may be retrograde menstruation,
metastatic spread, coelomic
metaplasia and altered immunity.
Risk factors are prolonged
menstrual flow, early menarche,
delayed child-bearing and
immune disorders. Diagnosis is by
laparoscopy and biopsy; there is
no known cure and eventually
there may be secondary infertility
due to scarring of the pelvis and
abdomen so that the normal anatomy is modified.
- Adenomyosis is a form of endometriosis limited to the uterine wall. Clinical
signs include a bloated and enlarged uterus. Risk factors include high parity and
uterine surgery. Usually occurs in women aged 35 or older. Hysterectomies are
diagnostic and curative. Histologically it is characterized by cystically dilated
, endometrial glands on the uterine wall and positive staining for hemosiderin
(Pearls Prussian blue) underneath the cysts due to digestion of blood.
Whilst both conditions may be asymptomatic, they are usually characterized by chronic
pelvic pain, poorly responsive to NSAIDs, dysmenorrhea, dyspareunia and reduced
fertility. Both are estrogen-dependent diseases that have multifactorial etiologies.
Clinical manifestations
- Endometriosis in the recto-uterine Douglas pouch may lead to vaginal bleeding
due to response to estrogen exposure and progressive fibrosis
- In the ovary, endometriotic foci take the form of ‘chocolate cysts’ that may rupture
due to increased pressure from the bloody content causing peritonitic pain; there
is chronic progression to fibrosis. This is the only location where endometriosis
may lead to ovarian cancer, because of the peculiar pro-proliferative
microenvironment rich in cytokines and growth factors.
- In the intestinal wall, endometriosis may lead to obstruction. Notice that
histologically, endometriosis in the intestine may resemble an adenocarcinoma
however we can differentiate between the two entities because endometriosis
involves the transposition of the entire mucosa and not only the epithelial part of
the gland; to confirm, we can use CD10 stain (positive in the presence of stromal
cells).
- In the cervix, endometriosis is visible upon observation of a highly cellular stroma
surrounding glands with overlying squamous epithelium of the ectocervix. HPV in
those areas is negative so it is not an adenocarcinoma
- In the lungs, endometriotic foci may bleed
Abnormal uterine bleeding (AUB)
Endometrial cancers are often detected
early because they manifest with abnormal
uterine bleeding, defined as bleeding from
the uterine corpus that is abnormal in
volume, regularity and/or timing that has
been present for the majority of the last 6
months. Bleeding outside the fertile period
and especially in the perimenopausal and
postmenopausal period should raise
suspicion for organic lesions → these
patients should undergo
US examinations and
gynecological visits;
upon detection of a
thickened endometrium,
these patients should
perform hysteroscopy
with biopsy.
Causes of AUB may be
benign, like polyps and
