Epidemiology of Adnexal Tumors

The determination of the precise frequency of adnexal masses is impossible as some adnexal tumors go undiagnosed. A variety of age groups need to be considered while estimating the clinical significance of adnexal masses.

Children to adolescents

Nearly 80% of ovarian cysts in girls under 9 years are malignant and those are mostly germ cell tumors.

About half of the adnexal neoplasms in adolescent girls are mature cystic teratomas or dermoid cysts. Women who have a Y chromosome-carrying gonad stand a 25% chance of developing a cancerous growth.

Overall, about 10% of ovarian cancers were found to be hereditary. Patients with a family history of a non-polyposis colorectal cancer syndrome or breast-ovarian cancer syndrome were at an increased risk for developing cancerous tumors.

Endometriosis, though not common in adolescence, may be present in about half of women who have a painful mass. In adolescent women who are sexually active, tubo-ovarian abscess must be considered as a possible cause of an adnexal mass.


Most adnexal masses in reproductive age women are benign cysts. Only 10% of masses are malignant. The rate of malignancy is low in patients aged under 30.

About 25% of adnexal growths are endometriomas, 33% are mature cystic teratomas, and the rest are functional cysts or serous or mucinous cystadenomas.

No matter what the age group is, physicians must take into account the possibility of structural deformities and uterine masses. Also, in all premenopausal women, pregnancy-related adnexal masses such as ectopic pregnancy, corpus luteum cysts, theca lutein cysts, and luteomas should be considered.

Research findings

A research conducted by the Duke Evidence-based Practice Center on a contract with the Agency for Healthcare Research and Quality found that ovarian cancer is the leading cause of death from gynecologic malignancies in the US. The annual incidence of ovarian cancer was over 25,000 with an annual mortality of about 14,000.

According to the study, the incidence of cancer dramatically increases with age, though it is relatively uncommon before age 50. The incidence of ovarian cancer also varies by race and ethnicity. Incidence as well as mortality is the highest for white women.

The study also assessed the prevalence of various types of tumor in women in the U.S. population with adnexal tumors arranged by age, cancer status, size of tumor, and menopausal status.

The research collected data from case studies and screening studies with results given for all women having an undiagnosed mass. Results from the 20 articles that satisfied the inclusion criteria showed that in post-menopausal women the incidence of malignant masses is between 0.09 and 0.18% and that of benign tumors is 0.08 to 1.3%.

In a study group that included women with a family history of ovarian, breast, or colorectal cancer and postmenopausal women, the prevalence of malignant tumors was 0.10 to 0.11%, that of borderline tumors was 0.02%, and that of benign tumors was 1.1 to 1.2%.

Granulosa cell tumors, primary ovarian carcinoma such as mucinous and serous cystadenocarcinoma, and undifferentiated adenocarcinoma were the most prevalent malignant masses. The most common benign masses were paratubal cyst - 0.1 - 0.16%, serous cystadenoma - 0.4 - 0.7%, mature teratoma - 0.02 - 0.08%, and endometrioma - 0.03 - 0.3%.

An estimation of age-specific incidence of specific adnexal tumor types is difficult with the literature available.


  1. Medscape, Adnexal Tumors,             http://emedicine.medscape.com/article/258044-overview#showall
  2. Management of Adnexal Mass, https://archive.ahrq.gov/

Further Reading

Last Updated: May 25, 2023

Susha Cheriyedath

Written by

Susha Cheriyedath

Susha is a scientific communication professional holding a Master's degree in Biochemistry, with expertise in Microbiology, Physiology, Biotechnology, and Nutrition. After a two-year tenure as a lecturer from 2000 to 2002, where she mentored undergraduates studying Biochemistry, she transitioned into editorial roles within scientific publishing. She has accumulated nearly two decades of experience in medical communication, assuming diverse roles in research, writing, editing, and editorial management.


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