IV. Benign conditions
After completing this section you will be able to:
- list common benign non-neoplastic diseases of the endometrium
- discuss possible etiologic factors
- describe clinical presentation
- describe histologic features
- state possible outcome
- Dysfunctional uterine bleeding (DUB)
This is a clinical term used to describe abnormal uterine bleeding not attributable
to a pathologic lesion of the endometrium or uterus. It is due to deranged
magnitude or duration of hormonal (estrogen/progesterone) effects on the endometrium.
The cause is usually due to ovarian dysfunction, which may result in anovulation
or in luteal phase defect.
This refers to the absence of ovulation during the reproductive years (in
the absence of pregnancy) and is the commonest cause of DUB. Anovulation can
occur at any age but more commonly occurs at menarche and at menopause. In
an anovulatory cycle, the failure of ovulation leads to excessive and prolonged
estrogen stimulation, with absence of the postovulatory surge in progesterone
levels. This results in a disordered proliferative endometrium. The spiral
arterioles do not develop properly in the absence of progesterone. When estrogen
levels decline, there is loss of stromal fluid causing collapse of the poorly
developed spiral arterioles, stasis, and thrombosis and "break-through
bleeding" occurs. In some cases, there is no drop in estrogen levels
and bleeding occurs because adequate blood supply to the proliferating endometrium
cannot be maintained. The exact cause of anovulation is not really understood.
Histologic appearances reflect the effect of estrogen stimulation without
subsequent progesterone stimulation. The endometrial glands are proliferative
and show mild architectural changes including cystic dilatation. Breakdown
of the stroma results in fragmented, isolated glands with no evidence of secretory
Dysfunctional uterine bleeding. Fragmented glands and stroma.
Luteal phase defect
Luteal phase defect refers to the occurrence of inadequate corpus luteum
function resulting in inadequate progesterone output and an abnormally short
menstrual cycle. This dysfunction occurs when the corpus luteum does not develop
properly or regresses prematurely. It manifests clinically as infertility
with increased bleeding or amenorrhea.
The histologic findings are those of secretory endometrium more than 2 days
out of phase with the chronologic day of the menstrual cycle.
This is the presence of benign endometrial glands and stroma outside the
uterus. The lesions are usually found on the peritoneal surfaces of the reproductive
organs and adjacent pelvic organs. The most frequent location is the ovary
(approx. 50%) followed by the pouch of Douglas, uterosacral ligaments, posterior
surface of the uterus and the remaining pelvic peritoneum. Occasional sites
include the cervix, vagina, perineum, bladder, large bowel and the umbilicus.
Rare lesions are seen as far afield as small bowel, kidneys, lungs and brain.
Several theories have been used to explain the occurrence of endometriosis:
Menstrual implantation: This proposes that fragments of menstrual
endometrium regurgitate through the fallopian tubes and implant on various
sites in the pelvic peritoneum.
Vascular dissemination: Suggests that occurrence of endometriosis
may be due to hematogenous or lymphatic spread from the endometrium.
Celomic metaplasia: The lining of the peritoneal cavity originates
from the embryonic celomic epithelium, which also gives rise to the müllerian
duct system from which the uterus and tubes develop. It is proposed that endometriosis
arises from celomic metaplasia of the peritoneum.
Question: Can endometriosis occur in males (who do not have any endometrial
The clinical presentation depends on the site of endometriosis. Dysmenorrhea,
cyclic abdominal pain and dyspareunia are common symptoms. Infertility occurs
in about a third of affected women.
Endometriosis usually appears as multiple red, purplish or brown (due to
presence of hemosiderin) 1mm to 5mm nodules, but some may form larger masses
or cysts. Dense fibrous adhesions may surround the foci. Repeated hemorrhage
into foci in the ovary with each menstrual cycle produces cysts, which contain
inspissated, chocolate-brown material, called "chocolate cysts".
Microscopic diagnosis of endometriosis is made by the presence of ectopic
endometrial glands and stroma. Macrophages containing hemosiderin (siderophages)
and ceroid may be present in lesions with previous hemorrhage. In others,
the endometrial tissue is inactive and no evidence of past bleeding is seen.
When endometriosis develops in a muscular viscus, the smooth muscle around
it is often hyperplastic.
Benign with no malignant potential. May recur after surgical excision but
the risk is low.
Question: What complication can arise when endometriosis involves
This is defined as the presence of endometrial glands and stroma in the myometrium.
The condition involves the posterior wall more often than the anterior but
it may affect both walls in the same uterus.
The disease is primarily a disorder of parous women and occurs infrequently
in the nullipara. It is associated with menorrhagia and increasingly severe
secondary dysmenorrhea. In about a third of patients there are no symptoms
and the lesions are discovered accidentally.
When extensive the lesions produce myometrial thickening. On section the
thickened myometrium presents a whorled and trabeculated appearance with small
yellow or brown cystic spaces containing fluid or blood. Sometimes small hemorrhagic
areas of endometrial islands can be seen.
Occasionally, a proliferation of smooth muscle around a focus of adenomyosis
produces a tumor called adenomyoma, which resembles uterine leiomyoma.
Adenomyosis. Endometrial gland and stroma in myometrium.
Adenomyosis. Another example.
This is a benign condition with no known malignant potential that regresses
after the menopause.