Ovarian cyst
文摘
科学
2024-07-24 07:00
澳大利亚
If you would like to view past exciting content, please click on the following link.The term "cyst" is derived from the Greek word "kustis," which translates to "pouch." Consequently, ovarian cysts are described as fluid-filled sacs located on or within the ovaries. These cysts are prevalent among females during their reproductive years, though they can occur at any age.Ovaries are a pair of pale organs, each roughly the size of a walnut. They are situated slightly above and to either side of the uterus and fallopian tubes, held in place by ligaments. These include the broad ligament, the ovarian ligament, and the suspensory ligament. The suspensory ligament is particularly critical as it carries the ovarian artery, vein, and nerve plexus to the ovary.Upon dissecting an ovary (which should not be attempted outside of a professional setting), you would observe an inner layer known as the medulla that houses most of the blood vessels and nerves, and an outer layer called the cortex, dotted with ovarian follicles.Each follicle begins with a primary oocyte—an immature sex cell—surrounded by theca and granulosa cells.Throughout the menstrual cycle, the ovaries undergo significant activity, regulated by the hypothalamus and the pituitary gland in the brain. The hypothalamus releases gonadotropin-releasing hormone (GnRH), prompting the anterior pituitary to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH).During the follicular phase in the first two weeks of a typical 28-day cycle, several follicles compete to become the dominant follicle for release at ovulation, while others regress and perish. These developing follicles produce significant amounts of estrogen, which inhibits the pituitary's release of FSH, and also produce androgens like testosterone.At ovulation, the oocyte is expelled into the fallopian tube, marking the start of the luteal phase, which lasts through the second half of the cycle. The corpus luteum, the remainder of the ovarian follicle, then secretes progesterone, inhibiting LH from the pituitary.Should fertilization occur, the corpus luteum continues to produce progesterone until the placenta is established. If no fertilization takes place, the corpus luteum ceases hormone production after about 10 days, becomes fibrotic, and is known as the corpus albicans.Regarding ovarian cysts, there are primarily two broad categories. Functional cysts arise from disruptions in the typical cyclic development of ovarian follicles. A common type of functional cyst, the follicular cyst, forms when a dominant follicle does not rupture and continues to grow due to an absent LH surge, which is normally responsible for triggering ovulation during a menstrual cycle.Polycystic ovary syndrome (PCOS) is a condition characterized by multiple follicular cysts due to a dysfunction in the hypothalamic-pituitary-ovarian axis, leading to chronic anovulation. This often results in amenorrhea, or the absence of menstruation, and elevated androgen levels.Another scenario involves the corpus luteal cyst, which occurs when the dominant follicle ruptures during ovulation but then seals itself. Instead of dissolving, the corpus luteum enlarges. This growth can cause the nourishing arteries to rupture, leading to internal bleeding, hence why these are also referred to as hemorrhagic cysts.Both follicular and corpus luteal cysts are typically 2 to 3 centimeters in diameter, but can grow up to 10 centimeters. They contain a clear, serous liquid and have a smooth internal lining, classifying them as "simple cysts."Theca lutein cysts represent another type of functional cyst, triggered by excessive stimulation from human chorionic gonadotropin (hCG), a hormone produced during pregnancy. These cysts usually affect both ovaries, as hCG promotes the growth of theca cells in resting follicles. Conditions with elevated hCG levels, such as multiple pregnancies or gestational trophoblastic disease—a condition involving tumor formation from placental cells—often see the development of theca lutein cysts.Turning to neoplastic cysts, these are formed from the abnormal proliferation of cells on or within the ovaries, leading to either benign or malignant masses. Neoplastic cysts are generally complex; they are larger than 10 centimeters, feature irregular borders, and often have internal septations that give them a multilocular appearance. The contents of these cysts are heterogeneous, meaning they include various substances beyond just fluid.Endometriomas are a type of benign neoplastic cyst occurring in cases of endometriosis, where endometrial tissue from the uterus forms on the ovaries. Functionally similar to uterine endometrium, endometriomas respond to hormonal cycles and typically fill with old blood and shed tissue during menstruation, earning the nickname "chocolate cysts." They also release proinflammatory factors that promote inflammation and cyst growth, and can rupture, spilling contents into the peritoneal cavity.Finally, ovarian tumors, which often possess cystic features, fall under the broader category of neoplastic cysts due to their potential to form cyst-like structures from abnormal cell growth.First, let's discuss benign tumors. Some, like serous cystadenomas, arise from the surface ovarian epithelium and are often bilateral, filled with a watery fluid. Others originate from ovarian germ cells, such as mature cystic teratomas, also known as dermoid cysts. These are the most common ovarian tumors in young women and typically contain a diverse mix of mature tissues from two or three germ layers, including fat, muscle, teeth, nails, and hair, earning them the nickname "the Frankenstein's monster of tumors."Turning to malignant neoplastic cysts, these include conditions like serous or mucinous cystadenocarcinomas, which also develop from the surface ovarian epithelium, much like their benign counterparts.Ovarian cysts can lead to several complications. First, some cysts can become hemorrhagic, with internal bleeding. This is more prevalent with follicular and corpus luteal cysts. Another complication is rupture, where cyst contents spill into the peritoneal cavity, causing significant irritation, particularly in cases involving dermoid cysts with their complex tissue mix. Ruptures often occur spontaneously but can also follow sexual activity. A third major issue is ovarian torsion, where the ovary twists around its supporting suspensory ligament, potentially cutting off its blood supply. This is more likely when the ovary is enlarged, exceeding 5 centimeters, which can occur with any ovarian cyst.Many ovarian cysts remain asymptomatic, but when symptoms do appear, they typically include dull aching pain in the lower abdomen near the cyst, dyspareunia (pain during intercourse), and a sense of pressure that might affect urination and bowel frequency. Sudden, sharp, severe abdominal pain could indicate torsion, or a hemorrhagic or ruptured cyst. A ruptured cyst can also lead to low blood pressure and a rapid heart rate, and if the blood reaches the subphrenic space below the diaphragm, it may cause upper abdominal or shoulder pain.If cysts stem from polycystic ovary syndrome, additional symptoms like amenorrhea and hirsutism (excessive hair growth in areas typical for male-pattern hair growth) may be present. Endometriomas may cause painful menstruation and are linked to fertility issues. With ovarian torsion, symptoms can extend to nausea, vomiting, and a low-grade fever.Diagnosing an ovarian cyst typically begins with an abdominal ultrasound, and if clarity is needed, an MRI might follow. A blood test for cancer antigen 125 can help rule out a malignant ovarian tumor. However, definitive diagnosis of the cyst type is achieved through histologic analysis, usually conducted after surgical specimen collection or cyst removal.Treatment for ovarian cysts varies by type and size. Smaller cysts, under five centimeters, often resolve on their own and are usually managed through observation. This applies to functional cysts, benign neoplasms like endometriomas, and serous and mucinous adenomas. In cases of uncomplicated cyst rupture where the patient remains stable, expectant management with NSAIDs for pain is common. For cysts larger than five centimeters, removal via laparoscopy is typical. Surgery is also indicated for benign tumors that frequently cause symptoms, malignant tumors, severe hemorrhaging impacting vital signs, or ovarian torsion due to the risk of ovarian damage.Ovarian cysts are fluid-filled sacs located on or within the ovaries, categorized primarily into functional and neoplastic types.Functional cysts stem from disruptions in the ovaries' normal cyclic processes. These include follicular cysts, where the follicle doesn't rupture pre-ovulation, and luteal cysts, where the follicle ruptures but reseals. Specific functional cysts are linked with conditions like PCOS, due to chronic anovulation, and theca-lutein cysts, which occur during pregnancy from excessive HCG levels.Neoplastic cysts encompass various forms, including endometriomas, serous and mucinous cystadenomas, mature cystic teratomas, and malignant ovarian tumors.While many ovarian cysts do not produce symptoms, those that do may cause dull, aching pelvic pain. Sharp, sudden pain may indicate serious complications like rupture, hemorrhage, or ovarian torsion.Management strategies vary: small cysts often resolve with watchful waiting, but cysts larger than 5 centimeters, those causing complications, or appearing malignant typically require surgical intervention."Robbins Basic Pathology" Elsevier (2017)"Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)"Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)"CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)"Diagnosis and management of ovarian cyst accidents" Best Practice & Research Clinical Obstetrics & Gynaecology (2009)"Ovarian cyst removal influences ovarian reserve dependent on histology, size and type of operation" Women's Health (2018) - - - - - - - END - - - - - - -
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