From the Guidelines
Follicular cysts are a type of simple cyst on the ovary, but not all simple ovarian cysts are follicular cysts. Follicular cysts specifically form when a follicle (the fluid-filled sac containing an egg) fails to rupture during ovulation or when the fluid inside the ruptured follicle doesn't drain properly. These cysts are typically small (usually less than 3 cm), fluid-filled, and resolve on their own within 1-3 menstrual cycles without requiring treatment, as supported by the American College of Radiology's O-RADS US risk stratification and management system 1. Simple ovarian cysts, on the other hand, is a broader category that includes follicular cysts as well as other benign cysts like corpus luteum cysts (which form after ovulation) and theca-lutein cysts. All simple cysts share characteristics of being fluid-filled with thin walls and no solid components. Most simple cysts, regardless of type, are benign and asymptomatic, though larger ones may cause pelvic pain, bloating, or menstrual irregularities, as noted in a recent study published in the Journal of the American College of Radiology 1. The distinction matters clinically because the specific type of cyst can influence management decisions, though most simple cysts are monitored with ultrasound rather than immediately treated, according to the O-RADS US risk stratification and management system 1. Key characteristics of follicular cysts include:
- Small size (usually less than 3 cm)
- Fluid-filled
- Thin walls
- No solid components
- Resolve on their own within 1-3 menstrual cycles without requiring treatment In contrast, simple ovarian cysts can be larger and may cause symptoms, but are still typically benign and can be monitored with ultrasound. The American College of Radiology's guidelines suggest that simple cysts up to 10 cm in diameter can be safely monitored with ultrasound without surgical intervention, even in postmenopausal patients 1. Overall, the management of follicular cysts and simple ovarian cysts prioritizes monitoring with ultrasound and avoiding unnecessary surgical intervention, in order to minimize morbidity, mortality, and improve quality of life.
From the Research
Definition and Characteristics
- Follicular cysts are typically straightforward from both clinical and pathologic perspectives, but may have unusual features at various stages of life 2.
- They are often benign and may be indistinguishable from cystic granulosa cell tumors based on size alone 2.
- Helpful clues to the diagnosis of follicle cysts include the lack of nuclear grooves and lack of invagination of granulosa cells into the cyst wall 2.
Comparison to Simple Ovarian Cysts
- Follicular cysts and simple ovarian cysts are often used interchangeably, but the study by 3 suggests that they may be distinct entities, with 13.3% of non-neoplastic ovarian lesions being classified as follicular cysts and 13.3% as simple cysts.
- However, the study by 2 does not provide a clear distinction between the two, suggesting that follicular cysts may be a type of simple ovarian cyst.
Clinical Presentations
- Follicular cysts can present with a range of clinical symptoms, including precocious puberty, pelvic pain, or an incidentally discovered pelvic mass 2, 4, 5.
- They can also be associated with pituitary adenomas, and may be discovered incidentally during ultrasound examination 2, 5.