An ovarian lesion is any abnormal area of tissue on or within an ovary. The term is intentionally broad. It covers everything from a harmless fluid-filled cyst that resolves on its own to a solid tumor that needs surgical removal. If you’ve seen this phrase on an imaging report, it simply means something was found on your ovary that looks different from normal tissue. It does not automatically mean cancer. Up to 88% of ovarian cysts produce no symptoms at all and are discovered incidentally during imaging for something else entirely.
Why Doctors Use the Term “Lesion”
“Lesion” is a placeholder word. Radiologists and gynecologists use it when they can see that something is there but haven’t yet determined exactly what it is. Once further testing clarifies the picture, the lesion gets a more specific name: a cyst, a dermoid, an endometrioma, a fibroma, or in rarer cases, a malignant tumor. So “ovarian lesion” on a report is a starting point, not a diagnosis.
The broader medical term you may also encounter is “adnexal mass,” which refers to any growth near the uterus, including in the ovaries, fallopian tubes, or surrounding connective tissue. Some of these masses turn out to not even originate from the ovary. Paraovarian cysts, which arise from tissue near the fallopian tube, account for 10% to 20% of all adnexal cysts and are frequently mistaken for ovarian lesions on initial imaging. Peritoneal inclusion cysts (fluid trapped by adhesions around the ovary) and even pedunculated uterine fibroids can look like ovarian masses on a scan.
Types of Ovarian Lesions
Ovarian lesions fall into three broad categories: functional, benign, and malignant. A fourth category, borderline tumors, sits between benign and malignant.
Functional Cysts
These are the most common type. They form as a normal part of the menstrual cycle when a follicle either doesn’t release an egg or doesn’t shrink afterward. Hemorrhagic cysts, which contain blood from a ruptured blood vessel inside the follicle, also fall into this group. Functional cysts almost always resolve without treatment within 8 to 12 weeks.
Benign Growths
Dermoid cysts (also called mature teratomas) contain a bizarre mix of tissue types, including hair, fat, and sometimes teeth, because they arise from cells capable of developing into many tissue types. Endometriomas form when tissue similar to the uterine lining grows on the ovary, filling with old blood that gives them a dark, chocolate-colored appearance. These are closely tied to endometriosis and can cause painful periods and discomfort during intercourse. Fibromas and other solid benign tumors also occur but are less common.
Borderline Tumors
These account for 15% to 20% of ovarian epithelial tumors. They have some abnormal cell features but lack the aggressive invasion into surrounding tissue that defines true cancer. About 65% of borderline tumors are serous (arising from the ovary’s surface cells), while roughly 32% are mucinous. Endometriosis is an important precursor for some rarer subtypes. Borderline tumors generally have a much better prognosis than ovarian cancer, though they do require treatment and monitoring.
Malignant Tumors
Ovarian cancer makes up a small fraction of all ovarian lesions but is the primary concern driving the workup when a lesion is found. Solid masses are generally more worrying than fluid-filled ones, and lesions larger than 6 centimeters carry higher suspicion because they’re more likely to contain cancerous cells.
Common Symptoms
Most ovarian lesions cause no symptoms. When they do, the signs can be vague enough to overlap with digestive or urinary problems. Bloating, abdominal fullness, and a feeling of pressure in the pelvis are typical. Some people notice frequent urination from the mass pressing on the bladder, or difficulty with bowel movements. Painful intercourse, particularly with deep penetration, is another common complaint. Menstrual irregularities, including longer gaps between periods followed by heavier bleeding, can occur.
More dramatic symptoms happen when a cyst ruptures or the ovary twists on its blood supply (torsion). Rupture causes sudden, sharp, one-sided pelvic pain and occasionally internal bleeding that leads to rapid heart rate and low blood pressure. Torsion can cause intense pain and fever, and it requires emergency treatment to save the ovary.
How Ovarian Lesions Are Evaluated
Transvaginal ultrasound is the first-line tool for evaluating an ovarian lesion. It can distinguish between a simple fluid-filled cyst and a complex mass with solid areas, internal walls, or irregular projections. Radiologists use a standardized scoring system called O-RADS to communicate the level of concern:
- Category 1: Normal ovary, 0% malignancy risk
- Category 2: Almost certainly benign, less than 1% risk
- Category 3: Low risk, 1% to under 10%
- Category 4: Intermediate risk, 10% to under 50%
- Category 5: High risk, 50% or greater
If your report includes an O-RADS score, it gives you a concrete sense of how concerned your doctor is likely to be. Categories 1 and 2 typically need minimal or no follow-up. Category 3 usually calls for repeat imaging. Categories 4 and 5 generally lead to further workup or surgical evaluation. MRI and blood tests (like the protein marker CA-125) can help refine the picture when ultrasound findings are unclear, though CA-125 can be elevated by many non-cancerous conditions, including endometriosis and fibroids.
Monitoring vs. Surgery
The majority of ovarian lesions are watched rather than operated on. The decision depends on the type, size, appearance, and whether you’re pre- or postmenopausal.
Functional and hemorrhagic cysts get a repeat ultrasound in 8 to 12 weeks. If the cyst shrinks or disappears, that confirms it was physiologic and no further action is needed. Endometriomas that aren’t removed require yearly ultrasound because they carry a small risk of transforming over time. Dermoid cysts that aren’t surgically removed can also be safely monitored with annual ultrasound, as malignant transformation is quite rare.
For postmenopausal patients, the threshold for monitoring simple cysts has become more conservative in recent years. Current guidance supports follow-up rather than automatic surgery for simple cysts larger than 3 centimeters, a significant shift from earlier recommendations that flagged anything over 1 centimeter.
Surgery enters the conversation when a lesion is large, has worrisome features on imaging, or causes symptoms. Cysts over 5 to 6 centimeters raise the risk of ovarian torsion, which can cut off blood supply to the ovary. Emergency surgery is needed in those cases. For planned procedures, minimally invasive laparoscopic surgery is standard for most cysts, though very large masses (generally over 10 to 12 centimeters) may require a traditional open approach. In children and adolescents, doctors lean toward careful observation rather than surgery when possible, to preserve ovarian tissue and future fertility.
What Your Report Likely Means
If you’re reading this because an ovarian lesion appeared on your imaging, the odds are strongly in your favor. The vast majority of ovarian lesions are benign. Simple cysts in premenopausal women are so common they’re considered a normal finding. Even complex-appearing lesions frequently turn out to be hemorrhagic cysts, dermoids, or endometriomas, all of which are non-cancerous.
The key details to look for on your report are the size of the lesion, whether it’s described as simple (fluid-filled, thin-walled, no solid parts) or complex (thick walls, solid areas, internal blood flow), and the O-RADS category if one is assigned. These three pieces of information tell you more about your next steps than the word “lesion” alone ever could.