On examination of a 72-year-old post-menopausal female, a 3 cm right adnexal mass is found. What is the most likely diagnosis?

In a 72-year-old post-menopausal female, the presence of an adnexal mass raises significant concern, particularly for ovarian cancer. This demographic is at an increased risk for malignant processes, especially when considering the age and the characteristics of the mass.

Ovarian masses in postmenopausal women have a higher likelihood of being neoplastic compared to their premenopausal counterparts due to the associated hormonal changes and the cessation of regular ovulation. The size of the mass, being 3 cm, also suggests a more concerning entity, as larger masses are more frequently associated with malignancy.

While endometriomas, uterine cancer, and functional ovarian cysts can be considered in younger populations or those with different clinical features, they are less likely in this specific context due to the patient's age and post-menopausal status. Endometriomas typically occur in women of reproductive age and are associated with endometriosis, while functional cysts are often transient and occur during the reproductive years, resolving on their own. Uterine cancer, while possible, generally presents with symptoms such as abnormal bleeding rather than isolated adnexal findings.

Thus, in the context of a post-menopausal woman with a notable adnexal