Thecoma of the Ovary: Understanding Your Pathology Report

Section Editor: Kianoosh Keyhanian MD FRCPC
August 31, 2026

A thecoma is a noncancerous (benign) tumor of the ovary. It is made of cells that resemble theca cells, a normal cell type found in the ovary. Theca cells surround developing eggs and make hormones, and the cells in a thecoma often do the same. It belongs to a family of tumors called sex cord-stromal tumors.

Thecomas are uncommon. They make up roughly 1 percent of all ovarian tumors. Most occur after menopause, at an average age around 60, and they are unusual before the age of 30. Almost all involve one ovary only.

A thecoma is not cancer, and it does not spread to other parts of the body. What sets this tumor apart from other benign ovarian tumors is that it often makes hormones, and those hormones can affect the lining of the uterus. That is the part of this diagnosis with the most practical consequence, and it is covered below. This article will help you understand what this diagnosis means on your pathology report, what each term means, and why it matters for your care.

What causes a thecoma?

The cause of a thecoma is not known. In most cases, there is no identifiable reason why one person develops this tumor.

Researchers have described genetic changes in some thecomas, including an extra copy of chromosome 12 and changes affecting a gene called PTCH. Neither finding is tested for in routine practice, and neither will appear on your pathology report. A thecoma is not inherited, and having one does not mean your relatives are at risk.

What are the symptoms?

The symptoms of a thecoma come from two sources: the hormones the tumor makes, and the size of the tumor itself. Hormone-related symptoms are the more common of the two, and they are often what leads to the tumor being found.

Bleeding after menopause — Most thecomas make estrogen. In someone who has been through menopause, extra estrogen thickens the lining of the uterus and can cause bleeding. A doctor should assess any bleeding after menopause.
Changes in menstrual bleeding — Before menopause, extra estrogen can cause heavy, prolonged, or irregular periods.
Male-pattern changes — A smaller number of thecomas make androgens, the male-type hormones. These can cause increased body or facial hair, thinning scalp hair, acne, a deeper voice, or periods stopping.
Abdominal or pelvic pain — A large tumor can cause discomfort or a feeling of pressure low in the abdomen.
Abdominal swelling — A large tumor can make the abdomen feel full or look enlarged.

Some thecomas cause no symptoms and are found by chance during imaging or surgery for another reason. Occasionally a thecoma causes fluid to collect in the abdomen and around the lung, a combination called Meigs syndrome. This resembles advanced ovarian cancer, and the blood test CA-125 can be raised as well. The fluid clears once the tumor is removed.

How is the diagnosis made?

A thecoma is diagnosed after the tumor is removed surgically and examined under the microscope by a pathologist. The surgery usually removes the whole ovary, often along with the fallopian tube on the same side. In someone past menopause, the uterus is sometimes removed at the same operation, particularly when the lining of the uterus is already known to be abnormal.

Imaging tests such as ultrasound, CT, or MRI show a firm, solid mass in the ovary. Imaging cannot separate a thecoma from other solid ovarian tumors, including cancers. A solid ovarian mass on a scan is usually reported as needing surgery to establish the diagnosis. Blood tests are sometimes suggestive rather than conclusive, since a thecoma can raise the hormone inhibin, and a raised CA-125 may occur when there is fluid in the abdomen.

During the operation, the surgeon may request an intraoperative consultation, also called a frozen section. The pathologist examines a piece of the tumor while the patient is still in the operating room and gives a preliminary diagnosis within minutes. That result can change how much tissue the surgeon removes. The pathologist makes the final diagnosis later, once the whole tumor has been examined in detail.

The pathologist’s main task is separating a thecoma from other tumors made of similar-looking cells. Additional stains and, in some cases, genetic testing are used for this purpose, as described below.

What does a thecoma look like under the microscope?

A thecoma is a benign ovarian tumor made of cells that resemble the theca cells of the normal ovary. To the naked eye, it is usually a firm, solid tumor with a yellow cut surface. The yellow color comes from fat stored inside the tumor cells, and it is a useful clue that separates a thecoma from the white cut surface of an ovarian fibroma. Under the microscope, the pathologist looks for the following features.

Large, pale cells — The tumor cells are large and rounded, with abundant pale or pink-grey cytoplasm, the material that fills a cell around its center. The cytoplasm looks pale because it contains fat droplets.
Indistinct cell borders — The edges between neighboring cells are hard to see, so the cells appear to blend into one another.
Round, uniform nuclei — The nucleus is the part of the cell that holds the genetic material. In a thecoma, the nuclei are round and even in size. Marked variation in size and shape, called nuclear atypia, is not seen.
Sheets and nests — The cells are arranged in broad groups called sheets, or in smaller rounded clusters called nests.
Bands of collagen — Thick, firm bands of supporting tissue often run between the groups of cells. The report may describe these as hyalinized plaques.
Rare dividing cells — A cell caught in the act of dividing is called a mitotic figure. These should be rare in a thecoma.

Immunohistochemistry

Immunohistochemistry is a laboratory test that uses antibodies to detect specific proteins inside cells. For a thecoma, these stains confirm that the tumor comes from the ovary’s hormone-producing and supporting cells. They also help separate it from other tumors that can look similar. If the tests were performed, your report lists the results as protein names with positive or negative beside each one.

Inhibin and calretinin. Typically positive throughout the tumor. These proteins are made by the hormone-producing cells of the ovary, and strong widespread staining is characteristic of a thecoma. In a fibroma, the same stains are usually only patchy.
SF-1. Usually positive. SF-1, or steroidogenic factor 1, is present in cells that make steroid hormones, which fits a tumor that produces estrogen or androgens.
WT1. Usually positive. WT1 is commonly present in tumors that arise from ovarian supporting tissue.
Estrogen receptor and progesterone receptor. Often positive. The estrogen receptor and progesterone receptor are proteins that respond to female hormones. A positive result is expected and does not mean hormone treatment is needed.
Cytokeratin and EMA. Usually negative. These proteins are found in tumors that arise from lining cells. Negative results argue against an ovarian carcinoma or a tumor that spread from elsewhere.

Two further tests are used when the appearance overlaps with an adult granulosa cell tumor, which is a low-grade cancer. A reticulin stain outlines the fibers around the cells, and the pattern differs between the two tumors. Testing for a specific change in the gene FOXL2 is more definitive because that change is found in most adult granulosa cell tumors and is absent in thecomas. Note that the FOXL2 protein stain can be positive in both, so it is the gene test rather than the stain that settles the question.

What is a luteinized thecoma?

A luteinized thecoma is a thecoma that contains clusters of cells resembling those of the corpus luteum. This hormone-producing structure forms in the ovary after an egg is released. These cells have bright pink cytoplasm and stand out from the rest of the tumor. A luteinized thecoma is still benign and is treated the same way as an ordinary thecoma.

Two things distinguish this form. It tends to occur in younger patients, including women under 30. It is also the form most likely to produce androgens rather than estrogen. A patient with a luteinized thecoma may therefore have male-pattern hair growth or a deeper voice rather than abnormal bleeding.

There is a rare and separate condition called luteinized thecoma associated with sclerosing peritonitis. It involves both ovaries, occurs in younger women, and causes scarring of the lining of the abdomen along with fluid buildup and bowel problems. Current classifications treat it as a distinct entity rather than a form of thecoma, and manage it differently. If your report mentions sclerosing peritonitis, ask your doctor to explain how it applies to your case.

How is a thecoma different from other ovarian tumors?

A thecoma is made of cells that overlap in appearance with several other ovarian tumors. Your report may mention any of the following, and the distinctions matter because they are not all benign.

Fibroma — Made of spindle-shaped cells and abundant collagen, with a white cut surface rather than yellow. An ovarian fibroma is also benign, and the two tumors are managed the same way.
Fibrothecoma — A tumor containing features of both. A fibrothecoma is benign, and the term is used when the pathologist sees a genuine mixture.
Adult granulosa cell tumor — A low-grade cancer that can contain areas resembling a thecoma. This is the most important distinction to get right, and it is why reticulin and FOXL2 testing are used.
Steroid cell tumor — Another hormone-producing ovarian tumor. Most are benign, but some behave differently, so clinicians separate the two carefully.

You may come across the term “malignant thecoma” in older writing or online. That term is no longer used. Tumors once given that name are now classified as other diagnoses, most often fibrosarcoma or a granulosa cell tumor. Today, a thecoma is benign.

What does a thecoma mean for the lining of the uterus?

This is the part of a thecoma diagnosis with the most practical consequence. Because most thecomas make estrogen, and estrogen makes the lining of the uterus grow, the endometrium is affected in a substantial number of patients. Studies have found thickening of the lining, called endometrial hyperplasia, in roughly 15 percent of patients with a thecoma, and endometrial cancer in roughly 20 percent.

For this reason, assessment of the lining of the uterus is a standard part of care after this diagnosis. If you have not already had an endometrial biopsy or a hysterectomy, your doctor will usually arrange for the lining to be checked. If the uterus was removed at the same operation, your pathology report will describe the endometrium separately, and that section is worth reading alongside the ovarian diagnosis. Findings your report may describe include:

Normal endometrium — No abnormal growth is present.
Endometrial hyperplasia without atypia — The lining is thickened, and the glands are crowded, but the cells look normal. This is noncancerous and is usually treated with hormone therapy.
Endometrioid intraepithelial neoplasia — The glands are crowded,d and the cells look abnormal. This is a precancerous condition, also called atypical endometrial hyperplasia in older reports, and it is treated.
Endometrioid carcinoma — A cancer of the lining of the uterus. When found this way, it is usually caught early because the bleeding that led to the investigation happened early.

A finding in the endometrium does not change the fact that the ovarian tumor itself is benign. The two diagnoses are reported and managed separately.

What other findings may be described in the report?

Along with the diagnosis of thecoma, your pathology report may describe several other features of the tumor and the surrounding tissue.

Tumor size — The report gives the greatest dimension in centimeters. Size does not change the fact that the tumor is benign.
Cut surface — The report often notes a yellow cut surface, which reflects the fat stored inside the tumor cells.
One or both ovaries — Almost all thecomas involve only one ovary. Involvement of both ovaries is unusual and prompts the pathologist to consider other diagnoses.
The other tissues removed — The report describes the fallopian tube and, when removed, the uterus, cervix, and other ovary. Each is reported separately.

What happens after this diagnosis?

A thecoma is a benign ovarian tumor. It does not spread to other parts of the body, and complete surgical removal is the treatment. Because it is not cancer, it is not given a grade, and it is not assigned a stage. Grading and staging describe how a cancer is behaving and how far it has spread, and neither applies here.

What you and your gynecologic team discuss next depends on your age, whether the uterus was removed, and what the hormones were doing before surgery. Points the team may raise include:

Checking the lining of the uterus — If the uterus is still in place, this is usually the first step after the diagnosis, for the reasons described above.
No chemotherapy or radiation — These treatments are not used for a thecoma, because it is benign.
Recurrence — A thecoma does not come back once it has been completely removed.
Hormone symptoms settling — Abnormal bleeding usually stops once the tumor is removed. Male-pattern changes may take longer to improve, and some, such as a deeper voice, may not fully reverse.
Fertility — Removing one ovary does not usually prevent future pregnancy, since the other ovary continues to work. Fertility-sparing surgery is often possible for younger patients.

Most people need no further treatment for the ovarian tumor itself. Your doctor will tell you whether any follow-up is recommended in your situation.

Questions to ask your doctor

Was the diagnosis a thecoma or a luteinized thecoma?
Was there any concern that this could be a granulosa cell tumor?
Were reticulin or FOXL2 tests performed, and what did they show?
Was the tumor making estrogen, androgens, or both?
Has the lining of my uterus been checked?
If my uterus was removed, what did the report say about the endometrium?
How large was the tumor?
Was the tumor in one ovary only, or were both ovaries involved?
Was the ovary removed, and was the fallopian tube removed as well?
Will my symptoms settle now that the tumor is out?
Does this affect my fertility?
Do I need any follow-up imaging or appointments?
What symptoms should prompt me to contact you?