Abstract / Summary
Epididymal cysts represent a frequent benign scrotal finding in boys, yet their natural history throughout the pubertal transition remains insufficiently understood. Current clinical guidance is largely derived from adult data, and objective predictors of spontaneous regression during adolescence have not been established. This study aimed to retrospectively evaluate changes in epididymal cyst characteristics during puberty and explore clinical factors associated with cyst resolution. A retrospective cohort analysis was conducted in 74 boys with ultrasound-diagnosed epididymal cysts at Tanner stages 1 or 2 who underwent follow-up imaging at stages 3 or 4. Multivariable logistic regression and Cox proportional hazards modeling were applied to evaluate variables correlated with cyst resolution and the timing thereof. Receiver operating characteristic (ROC) analysis was performed as an exploratory analysis to assess the association between initial cyst diameter and cyst resolution. At a mean follow-up of 36.0 months, spontaneous resolution was documented in 18 of 74 patients (24.3%); all patients in the resolution group had an initial maximum cyst diameter < 10 mm. Lesions that resolved decreased from a median size of 3.0 mm (IQR: 2.5–4.0) to 0.0 mm (IQR: 0.0–0.0) ( P < 0.001), while those that persisted exhibited a slight increase from 4.8 mm (IQR: 3.0–7.0) to 5.0 mm (IQR: 3.3–10.8) ( P < 0.001). Baseline cyst diameter was independently associated with spontaneous resolution in both logistic regression (OR = 0.698 per mm, 95% CI 0.502–0.971) and Cox proportional hazards regression analyses (HR = 0.669 per mm, 95% CI 0.486–0.920). Older chronological age at entry was also associated with earlier regression (HR = 1.986 per year, 95% CI 1.182–3.335). An exploratory ROC analysis identified a 4.3-mm threshold (AUC: 0.713; sensitivity: 88.9%; specificity: 58.9%) associated with different resolution patterns; however, this threshold was derived and evaluated within the same cohort and requires independent validation. Pubertal epididymal cysts demonstrate heterogeneous trajectories, with approximately one-quarter undergoing complete spontaneous resolution and most persistent cysts showing minimal size change during follow-up. Initial cyst diameter was associated with spontaneous resolution and time to resolution in this cohort. The exploratory 4.3 mm threshold and model-derived grouping were derived from the same cohort and should be regarded as hypothesis-generating findings requiring independent prospective validation. Trial registration: Not applicable (observational study without health care intervention).