Purpose: To report a pediatric case of choroidal osteoma documented from its earliest detectable stage, characterize its growth pattern, and evaluate the impact of photodynamic therapy (PDT) on tumor progression. Observations: A 4-year-old female underwent cataract surgery in the right eye and was consequently followed regularly. At age 8.8 years old (4 years of follow-up), a subtle, amelanotic choroidal juxtapapillary lesion was detected in the left eye on fundus examination. A retrospective review of fundus photographs prior to this examination revealed no readily visible lesion at age 6.7 years. Subtle changes on fundus photography in intermediate timepoints were apparent only on close inspection. Multimodal imaging confirmed the diagnosis of choroidal osteoma. The lesion's effective basal diameter growth rate before PDT was 1.94 mm/year, faster than reported in pediatric cases. After PDT, the growth rate was 1.78 mm/year, which was not statistically different (p = 0.558). Over a five-year follow-up period, the patient maintained 20/20 visual acuity in the affected eye despite subfoveal involvement of the tumor. Conclusions and importance: This case represents a rare instance of photographic documentation of choroidal osteoma during its earliest identifiable stages, providing unique insight into this rare tumor's natural history and progression. While PDT was performed, it neither halted the tumor's progression completely nor prevented it from extending sub-foveally. These findings underscore the importance of early detection, longitudinal imaging, and continued exploration of management strategies for pediatric choroidal osteomas.