Ovarian cyst- causes, symptoms, diagnosis, treatment, pathology

Ovarian cyst- causes, symptoms, diagnosis, treatment, pathology


Learning medicine is hard work! Osmosis makes it easy. It takes your lectures and notes to create
a personalized study plan with exclusive videos, practice questions and flashcards, and so
much more. Try it free today! “Cyst” comes from kustis, which means
“pouch”, so ovarian cysts are fluid-filled sacs on or in the ovaries. They are very common in females of reproductive
age, but can affect females of any age. The ovaries are a pair of white-ish organs
about the size of walnuts. They’re held in place, slightly above and
on either side of the uterus and fallopian tubes by ligaments. Specifically, there’s the broad ligament,
the ovarian ligament, and the suspensory ligament. And the suspensory ligament is particularly
important because the ovarian artery, ovarian vein, and ovarian nerve plexus pass through
it to reach the ovary. If you slice the ovary open and look at it
(don’t try this at home) there’s an inner layer called the medulla, which contains most
of the blood vessels and nerves and an outer layer called the cortex, which has ovarian
follicles scattered throughout it. Each follicle is initially made up of an immature
sex cell, or primary oocyte, which is the female sex cell, and layers of theca and granulosa
cells surrounding the oocyte. Now, there’s actually loads going on with
the ovaries throughout the menstrual cycle, which is controlled by the hypothalamus and
the pituitary up in the brain. The hypothalamus secretes gonadotropin-releasing
hormone, or GnRH, which makes the nearby anterior pituitary gland release follicle-stimulating
hormone, or FSH, and luteinizing hormone, or LH. In the first two weeks of an average 28-day
cycle, the ovaries go through the follicular phase, meaning that out of the many follicles
scattered throughout the ovaries, a couple of them enter a race to become the dominant
follicle, that will be released at ovulation, while the rest regress and die off. All the developing follicles secrete loads
of estrogen, which negatively inhibits pituitary FSH, and they also make a few androgens like
testosterone. At ovulation, the oocyte is released into
the fallopian tube, and the luteal phase begins – which lasts for the last 2 weeks of an average
28-day cycle. During the luteal phase, the remnant of the
ovarian follicle, called the corpus luteum, makes progesterone, which negatively inhibits
pituitary LH. If fertilization occurs then the corpus luteum
continues making progesterone until the placenta forms. If fertilization doesn’t happen, then the
corpus luteum stops making hormones after approximately 10 days, becomes fibrotic, and
is called the corpus albicans. So as far as ovarian cysts go, there are 2
broad categories. First, there are functional cysts, which result
when the normal, cyclic development of the ovarian follicles is disrupted. One type of functional cyst that can form
before ovulation is a follicular cyst, which is a dominant follicle that fails to rupture
and keeps growing. This can happen, if say, the normal surge
of LH that causes ovulation just doesn’t happen during a given menstrual cycle. A condition where you might have multiple
follicular cysts is polycystic ovary syndrome, which is caused by a dysfunction in the hypothalamic-pituitary-ovarian
axis that causes chronic anovulation, which may lead to amenorrhea, or absent menstruation,
and excess androgen production. Alternatively, if the dominant follicle ruptures
but then closes up again after ovulation, this is called a corpus luteal cyst. In this case, the corpus luteum doesn’t
dissolve but instead continues to grow. As it grows, the arteries nourishing it can
rupture and hemorrhage into the cyst, which is why corpus luteal cysts are also called
hemorrhagic cysts. Both follicular and corpus luteal cysts are
usually around 2 to 3 centimeters, but they can get as big as 10 cm in diameter, they
contain a clear serous liquid, and have a smooth internal lining – so they are referred
to as “simple cysts”. The last kind of functional cysts are theca
lutein cysts. These are caused by overstimulation by human
chorionic gonadotropin or hCG, a hormone that’s produced by the placenta, so they’re only
seen in pregnancy. hCG stimulates growth of the follicular theca
cells, so these cysts are usually bilateral, since resting follicles can be found on both
ovaries. Theca lutein cysts are more likely to develop
when there’s more hCG than usual, like when there are multiple fetuses, or with gestational
trophoblastic disease, where tumours made up of placental cells causes higher than normal
hCG levels. Ok, now, the second category of cysts are
neoplastic cysts – which is not to say all of them are cancer, but rather that they’re
caused by the abnormal reproduction of cells on or in the ovaries, which can result in
a benign or malignant mass. Broadly speaking, neoplastic cysts are usually
complex, meaning that they’re larger than 10 centimeters, have irregular borders, and
have internal septations creating a multilocular appearance. The fluid inside these cysts tends to be heterogeneous,
meaning there’s something other than fluid inside it. Benign neoplastic cysts include endometriomas,
which occur in endometriosis, and it’s where endometrial tissue from the uterus grows on
the ovary. Because they’re functionally the same as
the endometrium inside the uterus, endometriomas respond to hormones just like the uterus would. Because of this, endometriomas tend to bleed
within the cyst cavity during menstruation, and over time, they fill up with old, dark
blood and shed tissue – hence why they’re sometimes also called “chocolate cysts”. Endometriomas also release proinflammatory
factors which cause inflammation, which leads to cyst growth. When they get too large, they can rupture
and spill their contents inside the peritoneal cavity. Ok, now let’s switch gears and look at ovarian
tumors – since they also have cystic characteristics, they’re also included under the umbrella
term of neoplastic cysts. First, there’s benign tumors. Some originate from surface ovarian epithelium,
such as serous cystadenomas, which are often bilateral and filled with a watery fluid,
and mucinous cystadenomas, which tend to be multilocular and contain a mucus-like fluid. Some originate from ovarian germ cells, such
as mature cystic teratomas, also called dermoid cysts. Mature cystic teratomas are the most common
ovarian tumors in young women and usually contain a heterogeneous mix of mature tissues
that come from two or three of the germ cell layers. So they can contain fat, muscle, teeth, nails,
hair – they’re pretty much the Frankenstein’s monster of tumors. Finally, the last category of neoplastic cysts
include malignant ovarian tumours, like serous or mucinous cystadenocarcinomas, which develop
from surface ovarian epithelium, just like their benign counterparts. Now, there are three important complications
of ovarian cysts. First, some cysts can become hemorrhagic,
meaning there is bleeding inside the cyst. This is more common with follicular and corpus
luteal cysts. Second, some cysts can rupture, which will
release their contents into the peritoneal cavity. That can be pretty irritating for the peritoneal
cavity. Think for example of a dermoid cyst, with
its mixture of tissues like hair and sebaceous fluid: that’s not something the peritoneal
cavity is meant to handle! Rupture can happen spontaneously but more
frequently it happens after sexual intercourse. A third complication is ovarian torsion, where
the ovary twists around the suspensory ligament. Since this ligament suspends the ovary and
contains the ovarian blood vessels within it, torsion can cut off the blood supply to
the ovary. A risk factor for this is when the ovary is
5 centimeters or larger, which can happen with all kinds of ovarian cysts. Now, many ovarian cysts are asymptomatic. When there are symptoms they include a dull
aching lower abdominal pain around the location of the cyst, dyspareunia, or pain during sexual
intercourse, and a feeling of pressure in the lower abdomen which can also cause frequent
urination and bowel movements. If the abdominal pain is sudden, sharp, and
severe, that might indicate ovarian torsion, or a hemorrhagic or ruptured cyst. With a ruptured cyst, there may also be low
blood pressure or a fast heart rate, and if the blood makes it to the subphrenic space
of the peritoneal cavity, which is right below the diaphragm, it may cause upper abdominal
or shoulder pain. If the cysts are the result of polycystic
ovary syndrome, you might also see amenorrhea and hirsutism, or excessive hair growth on
the chin and upper lip, chest, and back. Endometriomas can also cause dysmenorrhea,
or painful menstruation, and are associated with fertility issues. Finally, with ovarian torsion, there might
also be nausea, vomiting, and a low-grade fever. Diagnosing an ovarian cyst starts with an
abdominal ultrasound. If diagnosis is uncertain, an MRI can be done
for more information. A blood test for cancer antigen 125 might
be done to rule out a malignant ovarian tumor. Ultimately, histologic analysis is the only
way to get a definitive diagnosis of the type of cyst, and this is usually achieved by collecting
some cyst cells via ultrasound-guided aspiration, or following removal of the cyst. Treatment for ovarian cysts varies based on
type and size. Many simple cysts will get better on their
own. Broadly speaking, if the cyst is under five
centimeters, observation is usually the mainstay of treatment. This applies to both functional cysts and
benign neoplasms like endometriomas, as well as serous and mucinous adenomas. With uncomplicated cyst rupture where the
person is hemodynamically stable, “expectant management” is also used. They might only be given NSAIDs for pain. If the cyst is over five centimeters, it’s
usually removed by laparoscopy. Surgery is also done for benign tumors that
cause symptoms on a regular basis, for malignant tumors, if a cyst is hemorrhaging severely
and it’s affecting blood pressure and heart rate, or if there is ovarian torsion since
lack of blood flow can damage the ovaries. All right, as a quick recap… Ovarian cysts are fluid-filled sacs on or
in the ovaries. They can broadly be grouped as functional
and neoplastic cysts. Functional cysts result from a disruption
of the normal cyclic activity of the ovaries, and they include follicular cysts, which occur
when the follicle fails to rupture before ovulation, and luteal cysts, which is when
the follicle ruptured but then closed back up. Particular types of functional cysts are those
associated with PCOS, which happen because of chronic anovulation, and theca-lutein cysts,
which are only seen during pregnancy, when there’s too much HCG. On the other hand, neoplastic cysts include
endometriomas, serous and mucinous cystadenomas, and mature cystic teratomas, as well as malignant
ovarian tumors. Many ovarian cysts are asymptomatic, but when
it’s symptomatic, a dull, aching pelvic pain is common. A sharp, sudden pain could be a sign of one
of three potential complications of ovarian cysts: rupture, hemorrhage, and ovarian torsion. Small cysts can be expectantly managed, whereas
cysts over 5 centimeters, who cause complications, or those who appear malignant should be surgically
removed.

14 Comments

Leave a Reply

Your email address will not be published. Required fields are marked *