Yes, benign cysts commonly develop or enlarge over a 2-year period, and this behavior is well-documented across multiple organ systems.
The natural history of benign cysts demonstrates that they frequently remain stable over years, but development and growth over a 2-year timeframe is a recognized pattern that does not indicate malignancy.
Hepatic (Liver) Cysts
Simple hepatic cysts typically follow an indolent course without significant size changes over time, though some cysts do grow and it remains unclear why certain simple cysts enlarge while others remain stable 1. The 2022 EASL guidelines explicitly state there is no indication for follow-up of simple hepatic cysts regardless of size unless patients become symptomatic 1. This guideline acknowledges that cyst growth can occur incidentally as part of their natural behavior.
Ovarian Cysts
The evidence strongly supports that benign ovarian cysts commonly persist unchanged over extended periods:
In premenopausal women followed for a median of 42 months (range 18-94 months), most sonographically benign ovarian cysts remained unchanged in both size and appearance 2. Only 8.3% disappeared during follow-up, and notably, all disappearances occurred after more than 2 years 2.
In postmenopausal women with simple ovarian cysts, 46.3% resolved spontaneously and 43.9% persisted unchanged over the follow-up period 3. Only 7.94% transformed into complex cysts, and just 1.06% significantly increased in size 3. The malignancy risk was extremely low (one case of papillary serous carcinoma in 378 cysts) 3.
Breast Cysts
Complicated breast cysts in postmenopausal women followed for 2 years showed zero malignancy rate in a cohort of 183 cysts 4. The study demonstrated that benign complicated cysts can persist over this timeframe without concerning features 4.
Key Clinical Implications
A 2-year development period for a benign cyst is within the expected natural history and should not automatically raise suspicion for malignancy. The critical factors are:
Imaging characteristics matter more than timeline: Simple cysts with classic benign features (well-defined margins, appropriate signal characteristics, no solid components) can be observed regardless of when they developed 1, 5.
Stability or slow growth is reassuring: Most benign cysts either remain stable or grow slowly over years 2, 3.
Symptoms drive intervention, not timeline: The presence or absence of symptoms, compression of adjacent structures, or development of complications determines management—not the duration of cyst presence 1, 6.
Common Pitfall to Avoid
Do not assume that a cyst developing over 2 years is more suspicious than one present for longer. The imaging characteristics, anatomic location, and clinical context are far more important than the temporal pattern of development. Benign cysts can appear de novo or enlarge over months to years as part of their natural behavior.