Management of a 25mm Involuting Functional Physiological Follicle/Cyst
No follow-up imaging or intervention is required for a 25mm involuting functional physiological follicle/cyst in a premenopausal woman. 1, 2
Rationale for No Follow-Up
Cysts ≤3 cm (30mm) in premenopausal women are considered physiologic and require no additional management, as they represent normal ovarian function (follicles or corpus luteum). 1, 2
The ACR O-RADS US consensus guideline specifically states that simple cysts ≤5 cm in premenopausal patients require no additional management, and those ≤3 cm should be considered physiologic and consistent with normal physiology. 1
Your 25mm cyst falls well below both thresholds (25mm = 2.5 cm), making it a normal physiologic finding that does not warrant surveillance. 2
Understanding the Involuting Nature
The fact that this cyst is described as "involuting" further supports its benign functional nature, as most functional cysts resolve spontaneously within a few menstrual cycles without any treatment. 3
Functional follicular cysts typically wax and wane over time or resolve completely, representing normal ovarian cyclical changes rather than pathologic processes. 1
Risk of Malignancy
The risk of malignancy in simple ovarian cysts in premenopausal women is approximately 0.5%, and this applies to surgically removed cysts (which have selection bias toward higher risk). 1, 2
In a large study of 72,093 women, no simple cysts were diagnosed as cancer in women younger than 50 years (0 of 12,957 cysts). 1
Common Pitfalls to Avoid
Do not describe this as a "cyst" in the radiology report—instead, use the term "follicle" or "corpus luteum" to prevent unnecessary patient anxiety and avoid triggering unwarranted follow-up. 1
Avoid ordering oral contraceptives for treatment, as randomized controlled trials have shown that combined oral contraceptives do not hasten resolution of functional ovarian cysts and provide no benefit. 3
Do not recommend follow-up imaging for cysts this size in premenopausal women, as this represents overtreatment and unnecessary healthcare utilization. 2