Which type of ovarian mass is the most common and typically regresses spontaneously?

The most common type of ovarian mass that typically regresses spontaneously is the follicular cyst. These cysts are formed from normal ovarian follicles that fail to rupture during the ovulatory phase. Instead, these follicles continue to grow and accumulate fluid, leading to cyst formation. Follicular cysts are often discovered incidentally during pelvic examinations or imaging studies and are usually asymptomatic.

Most importantly, they have a high likelihood of resolution without intervention within one to three menstrual cycles. This natural regression is a key characteristic that distinguishes them from other types of ovarian masses.

In terms of the other options: corpus luteum cysts can also form and may regress, but they are not as common as follicular cysts and typically come from a function that has already completed ovulation. Dermoid cysts, or teratomas, are more complex structures that do not typically regress on their own and may require surgical intervention if symptomatic. Theca lutein cysts are associated with conditions such as gestational trophoblastic disease and are less common than follicular cysts.