Volumetric courses of the intraosseous and meningeal components of osteomeningiomas after cyproterone acetate treatment withdrawal.

OBJECTIVE

Progestin exposure, such as with cyproterone acetate (CPA), could increase the risk of developing osteomeningiomas (OMs). This study investigated the volumetric dynamics of the meningeal and intraosseous components of these tumors and their correlation following CPA discontinuation.

METHODS

This retrospective study included 17 patients with 21 OMs diagnosed during ongoing CPA treatment. Volumes of the meningeal and intraosseous components of the OMs were measured at multiple time points. Volume dynamics over time were modeled using linear, exponential, power, and Gompertz tumor growth models. Hormone receptor expression in both components was evaluated via immunohistochemical analysis in the 4 tumors on which surgery was performed.

RESULTS

The Gompertz tumor growth model was the most accurate in fitting the data. After CPA cessation, the meningeal component showed volume reduction in 95% of tumors (a substantial decrease in 40% and a modest decrease in 55% of tumors). The intraosseous component exhibited sustained growth in all cases, characterized by three distinct dynamics: slowing growth (40%), linear growth (45%), and pseudo-exponential growth (15%). A significant correlation was observed between the volumetric courses in the two components (rho = 0.49, p = 0.03). Hormone receptor analysis revealed no differences in expression between the two components.

CONCLUSIONS

While the meningeal and intraosseous components of OMs respond differently to CPA withdrawal, their growth dynamics remain correlated.